diff --git a/contracts/zero-ex/CHANGELOG.json b/contracts/zero-ex/CHANGELOG.json
index d63bbe7f68..4d8051b8ca 100644
--- a/contracts/zero-ex/CHANGELOG.json
+++ b/contracts/zero-ex/CHANGELOG.json
@@ -21,6 +21,10 @@
             {
                 "note": "refund ETH with no gas limit in FQT",
                 "pr": 155
+            },
+            {
+                "note": "Added an opt-in `PositiveSlippageAffiliateFee`",
+                "pr": 101
             }
         ]
     },
diff --git a/contracts/zero-ex/contracts/src/transformers/PositiveSlippageFeeTransformer.sol b/contracts/zero-ex/contracts/src/transformers/PositiveSlippageFeeTransformer.sol
new file mode 100644
index 0000000000..9ab087754b
--- /dev/null
+++ b/contracts/zero-ex/contracts/src/transformers/PositiveSlippageFeeTransformer.sol
@@ -0,0 +1,68 @@
+// SPDX-License-Identifier: Apache-2.0
+/*
+
+  Copyright 2021 ZeroEx Intl.
+
+  Licensed under the Apache License, Version 2.0 (the "License");
+  you may not use this file except in compliance with the License.
+  You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+  Unless required by applicable law or agreed to in writing, software
+  distributed under the License is distributed on an "AS IS" BASIS,
+  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  See the License for the specific language governing permissions and
+  limitations under the License.
+
+*/
+
+pragma solidity ^0.6.5;
+pragma experimental ABIEncoderV2;
+
+import "@0x/contracts-utils/contracts/src/v06/errors/LibRichErrorsV06.sol";
+import "@0x/contracts-utils/contracts/src/v06/LibSafeMathV06.sol";
+import "@0x/contracts-erc20/contracts/src/v06/IERC20TokenV06.sol";
+import "@0x/contracts-erc20/contracts/src/v06/LibERC20TokenV06.sol";
+import "../errors/LibTransformERC20RichErrors.sol";
+import "./Transformer.sol";
+import "./LibERC20Transformer.sol";
+
+
+/// @dev A transformer that transfers tokens to arbitrary addresses.
+contract PositiveSlippageFeeTransformer is
+    Transformer
+{
+    using LibRichErrorsV06 for bytes;
+    using LibSafeMathV06 for uint256;
+    using LibERC20Transformer for IERC20TokenV06;
+
+    /// @dev Information for a single fee.
+    struct TokenFee {
+        // The token to transfer to `recipient`.
+        IERC20TokenV06 token;
+        // Amount of each `token` to transfer to `recipient`.
+        uint256 bestCaseAmount;
+        // Recipient of `token`.
+        address payable recipient;
+    }
+
+    /// @dev Transfers tokens to recipients.
+    /// @param context Context information.
+    /// @return success The success bytes (`LibERC20Transformer.TRANSFORMER_SUCCESS`).
+    function transform(TransformContext calldata context)
+        external
+        override
+    returns (bytes4 success)
+    {
+        TokenFee memory fee = abi.decode(context.data, (TokenFee));
+
+        uint256 transformerAmount = LibERC20Transformer.getTokenBalanceOf(fee.token, address(this));
+        if (transformerAmount > fee.bestCaseAmount) {
+            uint256 positiveSlippageAmount = transformerAmount - fee.bestCaseAmount;
+            fee.token.transformerTransfer(fee.recipient, positiveSlippageAmount);
+        }
+
+        return LibERC20Transformer.TRANSFORMER_SUCCESS;
+    }
+}
diff --git a/contracts/zero-ex/package.json b/contracts/zero-ex/package.json
index 8d34cc6828..69891b899c 100644
--- a/contracts/zero-ex/package.json
+++ b/contracts/zero-ex/package.json
@@ -41,9 +41,9 @@
         "rollback": "node ./lib/scripts/rollback.js"
     },
     "config": {
-        "publicInterfaceContracts": "IZeroEx,ZeroEx,FullMigration,InitialMigration,IFlashWallet,IAllowanceTarget,IERC20Transformer,IOwnableFeature,ISimpleFunctionRegistryFeature,ITokenSpenderFeature,ITransformERC20Feature,FillQuoteTransformer,PayTakerTransformer,WethTransformer,OwnableFeature,SimpleFunctionRegistryFeature,TransformERC20Feature,TokenSpenderFeature,AffiliateFeeTransformer,MetaTransactionsFeature,LogMetadataTransformer,BridgeAdapter,LiquidityProviderFeature,ILiquidityProviderFeature,NativeOrdersFeature,INativeOrdersFeature,FeeCollectorController,FeeCollector,CurveLiquidityProvider",
+        "publicInterfaceContracts": "IZeroEx,ZeroEx,FullMigration,InitialMigration,IFlashWallet,IAllowanceTarget,IERC20Transformer,IOwnableFeature,ISimpleFunctionRegistryFeature,ITokenSpenderFeature,ITransformERC20Feature,FillQuoteTransformer,PayTakerTransformer,PositiveSlippageFeeTransformer,WethTransformer,OwnableFeature,SimpleFunctionRegistryFeature,TransformERC20Feature,TokenSpenderFeature,AffiliateFeeTransformer,MetaTransactionsFeature,LogMetadataTransformer,BridgeAdapter,LiquidityProviderFeature,ILiquidityProviderFeature,NativeOrdersFeature,INativeOrdersFeature,FeeCollectorController,FeeCollector,CurveLiquidityProvider",
         "abis:comment": "This list is auto-generated by contracts-gen. Don't edit manually.",
-        "abis": "./test/generated-artifacts/@(AffiliateFeeTransformer|AllowanceTarget|BootstrapFeature|BridgeAdapter|BridgeSource|CurveLiquidityProvider|FeeCollector|FeeCollectorController|FillQuoteTransformer|FixinCommon|FixinEIP712|FixinProtocolFees|FixinReentrancyGuard|FixinTokenSpender|FlashWallet|FullMigration|IAllowanceTarget|IBootstrapFeature|IBridgeAdapter|IERC20Bridge|IERC20Transformer|IFeature|IFlashWallet|ILiquidityProvider|ILiquidityProviderFeature|ILiquidityProviderSandbox|IMetaTransactionsFeature|INativeOrdersFeature|IOwnableFeature|ISimpleFunctionRegistryFeature|IStaking|ITestSimpleFunctionRegistryFeature|ITokenSpenderFeature|ITransformERC20Feature|IUniswapFeature|IZeroEx|InitialMigration|LibBootstrap|LibCommonRichErrors|LibERC20Transformer|LibFeeCollector|LibLiquidityProviderRichErrors|LibMetaTransactionsRichErrors|LibMetaTransactionsStorage|LibMigrate|LibNativeOrder|LibNativeOrdersRichErrors|LibNativeOrdersStorage|LibOwnableRichErrors|LibOwnableStorage|LibProxyRichErrors|LibProxyStorage|LibReentrancyGuardStorage|LibSignature|LibSignatureRichErrors|LibSimpleFunctionRegistryRichErrors|LibSimpleFunctionRegistryStorage|LibSpenderRichErrors|LibStorage|LibTokenSpenderStorage|LibTransformERC20RichErrors|LibTransformERC20Storage|LibWalletRichErrors|LiquidityProviderFeature|LiquidityProviderSandbox|LogMetadataTransformer|MetaTransactionsFeature|MixinBalancer|MixinBancor|MixinCoFiX|MixinCryptoCom|MixinCurve|MixinDodo|MixinDodoV2|MixinKyber|MixinMStable|MixinMooniswap|MixinOasis|MixinShell|MixinSushiswap|MixinUniswap|MixinUniswapV2|MixinZeroExBridge|NativeOrdersFeature|OwnableFeature|PayTakerTransformer|PermissionlessTransformerDeployer|SimpleFunctionRegistryFeature|TestBridge|TestCallTarget|TestCurve|TestDelegateCaller|TestFeeCollectorController|TestFillQuoteTransformerBridge|TestFillQuoteTransformerExchange|TestFillQuoteTransformerHost|TestFixinProtocolFees|TestFixinTokenSpender|TestFullMigration|TestInitialMigration|TestLibNativeOrder|TestLibSignature|TestLiquidityProvider|TestMetaTransactionsNativeOrdersFeature|TestMetaTransactionsTransformERC20Feature|TestMigrator|TestMintTokenERC20Transformer|TestMintableERC20Token|TestNativeOrdersFeature|TestPermissionlessTransformerDeployerSuicidal|TestPermissionlessTransformerDeployerTransformer|TestRfqOriginRegistration|TestSimpleFunctionRegistryFeatureImpl1|TestSimpleFunctionRegistryFeatureImpl2|TestStaking|TestTokenSpender|TestTokenSpenderERC20Token|TestTransformERC20|TestTransformerBase|TestTransformerDeployerTransformer|TestTransformerHost|TestWeth|TestWethTransformerHost|TestZeroExFeature|TokenSpenderFeature|TransformERC20Feature|Transformer|TransformerDeployer|UniswapFeature|WethTransformer|ZeroEx|ZeroExOptimized).json"
+        "abis": "./test/generated-artifacts/@(AffiliateFeeTransformer|AllowanceTarget|BootstrapFeature|BridgeAdapter|BridgeSource|CurveLiquidityProvider|FeeCollector|FeeCollectorController|FillQuoteTransformer|FixinCommon|FixinEIP712|FixinProtocolFees|FixinReentrancyGuard|FixinTokenSpender|FlashWallet|FullMigration|IAllowanceTarget|IBootstrapFeature|IBridgeAdapter|IERC20Bridge|IERC20Transformer|IFeature|IFlashWallet|ILiquidityProvider|ILiquidityProviderFeature|ILiquidityProviderSandbox|IMetaTransactionsFeature|INativeOrdersFeature|IOwnableFeature|ISimpleFunctionRegistryFeature|IStaking|ITestSimpleFunctionRegistryFeature|ITokenSpenderFeature|ITransformERC20Feature|IUniswapFeature|IZeroEx|InitialMigration|LibBootstrap|LibCommonRichErrors|LibERC20Transformer|LibFeeCollector|LibLiquidityProviderRichErrors|LibMetaTransactionsRichErrors|LibMetaTransactionsStorage|LibMigrate|LibNativeOrder|LibNativeOrdersRichErrors|LibNativeOrdersStorage|LibOwnableRichErrors|LibOwnableStorage|LibProxyRichErrors|LibProxyStorage|LibReentrancyGuardStorage|LibSignature|LibSignatureRichErrors|LibSimpleFunctionRegistryRichErrors|LibSimpleFunctionRegistryStorage|LibSpenderRichErrors|LibStorage|LibTokenSpenderStorage|LibTransformERC20RichErrors|LibTransformERC20Storage|LibWalletRichErrors|LiquidityProviderFeature|LiquidityProviderSandbox|LogMetadataTransformer|MetaTransactionsFeature|MixinBalancer|MixinBancor|MixinCoFiX|MixinCryptoCom|MixinCurve|MixinDodo|MixinKyber|MixinMStable|MixinMooniswap|MixinOasis|MixinShell|MixinSushiswap|MixinUniswap|MixinUniswapV2|MixinZeroExBridge|NativeOrdersFeature|OwnableFeature|PayTakerTransformer|PermissionlessTransformerDeployer|PositiveSlippageFeeTransformer|SimpleFunctionRegistryFeature|TestBridge|TestCallTarget|TestCurve|TestDelegateCaller|TestFeeCollectorController|TestFillQuoteTransformerBridge|TestFillQuoteTransformerExchange|TestFillQuoteTransformerHost|TestFixinProtocolFees|TestFixinTokenSpender|TestFullMigration|TestInitialMigration|TestLibNativeOrder|TestLibSignature|TestLiquidityProvider|TestMetaTransactionsNativeOrdersFeature|TestMetaTransactionsTransformERC20Feature|TestMigrator|TestMintTokenERC20Transformer|TestMintableERC20Token|TestNativeOrdersFeature|TestPermissionlessTransformerDeployerSuicidal|TestPermissionlessTransformerDeployerTransformer|TestRfqOriginRegistration|TestSimpleFunctionRegistryFeatureImpl1|TestSimpleFunctionRegistryFeatureImpl2|TestStaking|TestTokenSpender|TestTokenSpenderERC20Token|TestTransformERC20|TestTransformerBase|TestTransformerDeployerTransformer|TestTransformerHost|TestWeth|TestWethTransformerHost|TestZeroExFeature|TokenSpenderFeature|TransformERC20Feature|Transformer|TransformerDeployer|UniswapFeature|WethTransformer|ZeroEx|ZeroExOptimized).json"
     },
     "repository": {
         "type": "git",
diff --git a/contracts/zero-ex/src/artifacts.ts b/contracts/zero-ex/src/artifacts.ts
index c0455e1253..033dfdfe4a 100644
--- a/contracts/zero-ex/src/artifacts.ts
+++ b/contracts/zero-ex/src/artifacts.ts
@@ -29,6 +29,7 @@ import * as MetaTransactionsFeature from '../generated-artifacts/MetaTransaction
 import * as NativeOrdersFeature from '../generated-artifacts/NativeOrdersFeature.json';
 import * as OwnableFeature from '../generated-artifacts/OwnableFeature.json';
 import * as PayTakerTransformer from '../generated-artifacts/PayTakerTransformer.json';
+import * as PositiveSlippageFeeTransformer from '../generated-artifacts/PositiveSlippageFeeTransformer.json';
 import * as SimpleFunctionRegistryFeature from '../generated-artifacts/SimpleFunctionRegistryFeature.json';
 import * as TokenSpenderFeature from '../generated-artifacts/TokenSpenderFeature.json';
 import * as TransformERC20Feature from '../generated-artifacts/TransformERC20Feature.json';
@@ -48,6 +49,7 @@ export const artifacts = {
     ITransformERC20Feature: ITransformERC20Feature as ContractArtifact,
     FillQuoteTransformer: FillQuoteTransformer as ContractArtifact,
     PayTakerTransformer: PayTakerTransformer as ContractArtifact,
+    PositiveSlippageFeeTransformer: PositiveSlippageFeeTransformer as ContractArtifact,
     WethTransformer: WethTransformer as ContractArtifact,
     OwnableFeature: OwnableFeature as ContractArtifact,
     SimpleFunctionRegistryFeature: SimpleFunctionRegistryFeature as ContractArtifact,
diff --git a/contracts/zero-ex/src/index.ts b/contracts/zero-ex/src/index.ts
index 0cb9288c63..f8cf1eff4c 100644
--- a/contracts/zero-ex/src/index.ts
+++ b/contracts/zero-ex/src/index.ts
@@ -46,6 +46,7 @@ export {
     IZeroExContract,
     LogMetadataTransformerContract,
     PayTakerTransformerContract,
+    PositiveSlippageFeeTransformerContract,
     WethTransformerContract,
     ZeroExContract,
 } from './wrappers';
diff --git a/contracts/zero-ex/src/wrappers.ts b/contracts/zero-ex/src/wrappers.ts
index 79048e1404..649ecfb7d0 100644
--- a/contracts/zero-ex/src/wrappers.ts
+++ b/contracts/zero-ex/src/wrappers.ts
@@ -27,6 +27,7 @@ export * from '../generated-wrappers/meta_transactions_feature';
 export * from '../generated-wrappers/native_orders_feature';
 export * from '../generated-wrappers/ownable_feature';
 export * from '../generated-wrappers/pay_taker_transformer';
+export * from '../generated-wrappers/positive_slippage_fee_transformer';
 export * from '../generated-wrappers/simple_function_registry_feature';
 export * from '../generated-wrappers/token_spender_feature';
 export * from '../generated-wrappers/transform_erc20_feature';
diff --git a/contracts/zero-ex/test/artifacts.ts b/contracts/zero-ex/test/artifacts.ts
index e98c46aec1..fc628ab481 100644
--- a/contracts/zero-ex/test/artifacts.ts
+++ b/contracts/zero-ex/test/artifacts.ts
@@ -92,6 +92,7 @@ import * as NativeOrdersFeature from '../test/generated-artifacts/NativeOrdersFe
 import * as OwnableFeature from '../test/generated-artifacts/OwnableFeature.json';
 import * as PayTakerTransformer from '../test/generated-artifacts/PayTakerTransformer.json';
 import * as PermissionlessTransformerDeployer from '../test/generated-artifacts/PermissionlessTransformerDeployer.json';
+import * as PositiveSlippageFeeTransformer from '../test/generated-artifacts/PositiveSlippageFeeTransformer.json';
 import * as SimpleFunctionRegistryFeature from '../test/generated-artifacts/SimpleFunctionRegistryFeature.json';
 import * as TestBridge from '../test/generated-artifacts/TestBridge.json';
 import * as TestCallTarget from '../test/generated-artifacts/TestCallTarget.json';
@@ -209,6 +210,7 @@ export const artifacts = {
     LibERC20Transformer: LibERC20Transformer as ContractArtifact,
     LogMetadataTransformer: LogMetadataTransformer as ContractArtifact,
     PayTakerTransformer: PayTakerTransformer as ContractArtifact,
+    PositiveSlippageFeeTransformer: PositiveSlippageFeeTransformer as ContractArtifact,
     Transformer: Transformer as ContractArtifact,
     WethTransformer: WethTransformer as ContractArtifact,
     BridgeAdapter: BridgeAdapter as ContractArtifact,
diff --git a/contracts/zero-ex/test/transformers/positive_slippage_fee_transformer_test.ts b/contracts/zero-ex/test/transformers/positive_slippage_fee_transformer_test.ts
new file mode 100644
index 0000000000..9ce122bebf
--- /dev/null
+++ b/contracts/zero-ex/test/transformers/positive_slippage_fee_transformer_test.ts
@@ -0,0 +1,127 @@
+import { blockchainTests, constants, expect, getRandomInteger, randomAddress } from '@0x/contracts-test-utils';
+import { encodePositiveSlippageFeeTransformerData } from '@0x/protocol-utils';
+import { BigNumber } from '@0x/utils';
+
+import { artifacts } from '../artifacts';
+import {
+    PositiveSlippageFeeTransformerContract,
+    TestMintableERC20TokenContract,
+    TestTransformerHostContract,
+} from '../wrappers';
+
+const { ZERO_AMOUNT } = constants;
+
+blockchainTests.resets('PositiveSlippageFeeTransformer', env => {
+    const recipient = randomAddress();
+    let caller: string;
+    let token: TestMintableERC20TokenContract;
+    let transformer: PositiveSlippageFeeTransformerContract;
+    let host: TestTransformerHostContract;
+
+    before(async () => {
+        [caller] = await env.getAccountAddressesAsync();
+        token = await TestMintableERC20TokenContract.deployFrom0xArtifactAsync(
+            artifacts.TestMintableERC20Token,
+            env.provider,
+            env.txDefaults,
+            artifacts,
+        );
+        transformer = await PositiveSlippageFeeTransformerContract.deployFrom0xArtifactAsync(
+            artifacts.PositiveSlippageFeeTransformer,
+            env.provider,
+            env.txDefaults,
+            artifacts,
+        );
+        host = await TestTransformerHostContract.deployFrom0xArtifactAsync(
+            artifacts.TestTransformerHost,
+            env.provider,
+            { ...env.txDefaults, from: caller },
+            artifacts,
+        );
+    });
+
+    interface Balances {
+        ethBalance: BigNumber;
+        tokenBalance: BigNumber;
+    }
+
+    async function getBalancesAsync(owner: string): Promise<Balances> {
+        return {
+            ethBalance: await env.web3Wrapper.getBalanceInWeiAsync(owner),
+            tokenBalance: await token.balanceOf(owner).callAsync(),
+        };
+    }
+
+    async function mintHostTokensAsync(amount: BigNumber): Promise<void> {
+        await token.mint(host.address, amount).awaitTransactionSuccessAsync();
+    }
+
+    it('does not transfer positive slippage fees when bestCaseAmount is equal to amount', async () => {
+        const amount = getRandomInteger(1, '1e18');
+        const data = encodePositiveSlippageFeeTransformerData({
+            token: token.address,
+            bestCaseAmount: amount,
+            recipient,
+        });
+        await mintHostTokensAsync(amount);
+        const beforeBalanceHost = await getBalancesAsync(host.address);
+        const beforeBalanceRecipient = await getBalancesAsync(recipient);
+        await host
+            .rawExecuteTransform(transformer.address, {
+                data,
+                sender: randomAddress(),
+                taker: randomAddress(),
+            })
+            .awaitTransactionSuccessAsync();
+        expect(await getBalancesAsync(host.address)).to.deep.eq(beforeBalanceHost);
+        expect(await getBalancesAsync(recipient)).to.deep.eq(beforeBalanceRecipient);
+    });
+
+    it('does not transfer positive slippage fees when bestCaseAmount is higher than amount', async () => {
+        const amount = getRandomInteger(1, '1e18');
+        const bestCaseAmount = amount.times(1.1).decimalPlaces(0, BigNumber.ROUND_FLOOR);
+        const data = encodePositiveSlippageFeeTransformerData({
+            token: token.address,
+            bestCaseAmount,
+            recipient,
+        });
+        await mintHostTokensAsync(amount);
+        const beforeBalanceHost = await getBalancesAsync(host.address);
+        const beforeBalanceRecipient = await getBalancesAsync(recipient);
+        await host
+            .rawExecuteTransform(transformer.address, {
+                data,
+                sender: randomAddress(),
+                taker: randomAddress(),
+            })
+            .awaitTransactionSuccessAsync();
+        expect(await getBalancesAsync(host.address)).to.deep.eq(beforeBalanceHost);
+        expect(await getBalancesAsync(recipient)).to.deep.eq(beforeBalanceRecipient);
+    });
+
+    it('send positive slippage fee to recipient when bestCaseAmount is lower than amount', async () => {
+        const amount = getRandomInteger(1, '1e18');
+        const bestCaseAmount = amount.times(0.95).decimalPlaces(0, BigNumber.ROUND_FLOOR);
+        const data = encodePositiveSlippageFeeTransformerData({
+            token: token.address,
+            bestCaseAmount,
+            recipient,
+        });
+        await mintHostTokensAsync(amount);
+        await host
+            .rawExecuteTransform(transformer.address, {
+                data,
+                sender: randomAddress(),
+                taker: randomAddress(),
+            })
+            .awaitTransactionSuccessAsync();
+        expect(await getBalancesAsync(host.address)).to.deep.eq({
+            tokenBalance: bestCaseAmount,
+            ethBalance: ZERO_AMOUNT,
+        });
+        expect(await getBalancesAsync(recipient)).to.deep.eq({
+            tokenBalance: amount.minus(bestCaseAmount), // positive slippage
+            ethBalance: ZERO_AMOUNT,
+        });
+    });
+});
diff --git a/contracts/zero-ex/test/wrappers.ts b/contracts/zero-ex/test/wrappers.ts
index 4f97656f06..2d12b48462 100644
--- a/contracts/zero-ex/test/wrappers.ts
+++ b/contracts/zero-ex/test/wrappers.ts
@@ -90,6 +90,7 @@ export * from '../test/generated-wrappers/native_orders_feature';
 export * from '../test/generated-wrappers/ownable_feature';
 export * from '../test/generated-wrappers/pay_taker_transformer';
 export * from '../test/generated-wrappers/permissionless_transformer_deployer';
+export * from '../test/generated-wrappers/positive_slippage_fee_transformer';
 export * from '../test/generated-wrappers/simple_function_registry_feature';
 export * from '../test/generated-wrappers/test_bridge';
 export * from '../test/generated-wrappers/test_call_target';
diff --git a/contracts/zero-ex/tsconfig.json b/contracts/zero-ex/tsconfig.json
index ab85835a51..7cb1e96cd5 100644
--- a/contracts/zero-ex/tsconfig.json
+++ b/contracts/zero-ex/tsconfig.json
@@ -27,6 +27,7 @@
         "generated-artifacts/NativeOrdersFeature.json",
         "generated-artifacts/OwnableFeature.json",
         "generated-artifacts/PayTakerTransformer.json",
+        "generated-artifacts/PositiveSlippageFeeTransformer.json",
         "generated-artifacts/SimpleFunctionRegistryFeature.json",
         "generated-artifacts/TokenSpenderFeature.json",
         "generated-artifacts/TransformERC20Feature.json",
@@ -119,6 +120,7 @@
         "test/generated-artifacts/OwnableFeature.json",
         "test/generated-artifacts/PayTakerTransformer.json",
         "test/generated-artifacts/PermissionlessTransformerDeployer.json",
+        "test/generated-artifacts/PositiveSlippageFeeTransformer.json",
         "test/generated-artifacts/SimpleFunctionRegistryFeature.json",
         "test/generated-artifacts/TestBridge.json",
         "test/generated-artifacts/TestCallTarget.json",
diff --git a/packages/asset-swapper/CHANGELOG.json b/packages/asset-swapper/CHANGELOG.json
index 081ba314d0..e0107326e6 100644
--- a/packages/asset-swapper/CHANGELOG.json
+++ b/packages/asset-swapper/CHANGELOG.json
@@ -49,6 +49,10 @@
             {
                 "note": "Add an alternative RFQ market making implementation",
                 "pr": 139
+            },
+            {
+                "note": "Added an opt-in `PositiveSlippageAffiliateFee`",
+                "pr": 101
             }
         ]
     },
diff --git a/packages/asset-swapper/src/constants.ts b/packages/asset-swapper/src/constants.ts
index 524affb5cd..0efda7bea5 100644
--- a/packages/asset-swapper/src/constants.ts
+++ b/packages/asset-swapper/src/constants.ts
@@ -3,6 +3,7 @@ import { SignatureType } from '@0x/protocol-utils';
 import { BigNumber, logUtils } from '@0x/utils';
 
 import {
+    AffiliateFeeType,
     ExchangeProxyContractOpts,
     LogFunction,
     OrderPrunerOpts,
@@ -12,7 +13,11 @@ import {
     SwapQuoteRequestOpts,
     SwapQuoterOpts,
 } from './types';
-import { DEFAULT_GET_MARKET_ORDERS_OPTS, TOKENS } from './utils/market_operation_utils/constants';
+import {
+    DEFAULT_GET_MARKET_ORDERS_OPTS,
+    DEFAULT_INTERMEDIATE_TOKENS,
+    DEFAULT_TOKEN_ADJACENCY_GRAPH,
+} from './utils/market_operation_utils/constants';
 
 const ETH_GAS_STATION_API_URL = 'https://ethgasstation.info/api/ethgasAPI.json';
 const NULL_BYTES = '0x';
@@ -38,7 +43,6 @@ const PROTOCOL_FEE_MULTIPLIER = new BigNumber(70000);
 // default 50% buffer for selecting native orders to be aggregated with other sources
 const MARKET_UTILS_AMOUNT_BUFFER_PERCENTAGE = 0.5;
 
-const DEFAULT_INTERMEDIATE_TOKENS = [TOKENS.WETH, TOKENS.USDT, TOKENS.DAI, TOKENS.USDC];
 const DEFAULT_SWAP_QUOTER_OPTS: SwapQuoterOpts = {
     chainId: ChainId.Mainnet,
     orderRefreshIntervalMs: 10000, // 10 seconds
@@ -49,12 +53,14 @@ const DEFAULT_SWAP_QUOTER_OPTS: SwapQuoterOpts = {
         takerApiKeyWhitelist: [],
         makerAssetOfferings: {},
     },
+    tokenAdjacencyGraph: DEFAULT_TOKEN_ADJACENCY_GRAPH,
 };
 
 const DEFAULT_EXCHANGE_PROXY_EXTENSION_CONTRACT_OPTS: ExchangeProxyContractOpts = {
     isFromETH: false,
     isToETH: false,
     affiliateFee: {
+        feeType: AffiliateFeeType.None,
         recipient: NULL_ADDRESS,
         buyTokenFeeAmount: ZERO_AMOUNT,
         sellTokenFeeAmount: ZERO_AMOUNT,
@@ -86,9 +92,12 @@ export const INVALID_SIGNATURE = { signatureType: SignatureType.Invalid, v: 1, r
 
 export { DEFAULT_FEE_SCHEDULE, DEFAULT_GAS_SCHEDULE } from './utils/market_operation_utils/constants';
 
+export const POSITIVE_SLIPPAGE_FEE_TRANSFORMER_GAS = new BigNumber(30000);
+
 export const constants = {
     ETH_GAS_STATION_API_URL,
     PROTOCOL_FEE_MULTIPLIER,
+    POSITIVE_SLIPPAGE_FEE_TRANSFORMER_GAS,
     NULL_BYTES,
     ZERO_AMOUNT,
     NULL_ADDRESS,
diff --git a/packages/asset-swapper/src/index.ts b/packages/asset-swapper/src/index.ts
index 9797aecd97..1e9f326178 100644
--- a/packages/asset-swapper/src/index.ts
+++ b/packages/asset-swapper/src/index.ts
@@ -74,9 +74,10 @@ export { InsufficientAssetLiquidityError } from './errors';
 export { SwapQuoteConsumer } from './quote_consumers/swap_quote_consumer';
 export { SwapQuoter, Orderbook } from './swap_quoter';
 export {
-    AffiliateFee,
     AltOffering,
     AltRfqtMakerAssetOfferings,
+    AffiliateFeeType,
+    AffiliateFeeAmount,
     AssetSwapperContractAddresses,
     CalldataInfo,
     ExchangeProxyContractOpts,
diff --git a/packages/asset-swapper/src/quote_consumers/exchange_proxy_swap_quote_consumer.ts b/packages/asset-swapper/src/quote_consumers/exchange_proxy_swap_quote_consumer.ts
index 7e21e60b8f..6768c0c541 100644
--- a/packages/asset-swapper/src/quote_consumers/exchange_proxy_swap_quote_consumer.ts
+++ b/packages/asset-swapper/src/quote_consumers/exchange_proxy_swap_quote_consumer.ts
@@ -5,6 +5,7 @@ import {
     encodeCurveLiquidityProviderData,
     encodeFillQuoteTransformerData,
     encodePayTakerTransformerData,
+    encodePositiveSlippageFeeTransformerData,
     encodeWethTransformerData,
     ETH_TOKEN_ADDRESS,
     FillQuoteTransformerData,
@@ -16,8 +17,9 @@ import { BigNumber, providerUtils } from '@0x/utils';
 import { SupportedProvider, ZeroExProvider } from '@0x/web3-wrapper';
 import * as _ from 'lodash';
 
-import { constants } from '../constants';
+import { constants, POSITIVE_SLIPPAGE_FEE_TRANSFORMER_GAS } from '../constants';
 import {
+    AffiliateFeeType,
     CalldataInfo,
     ExchangeProxyContractOpts,
     MarketBuySwapQuote,
@@ -59,6 +61,7 @@ export class ExchangeProxySwapQuoteConsumer implements SwapQuoteConsumerBase {
         payTakerTransformer: number;
         fillQuoteTransformer: number;
         affiliateFeeTransformer: number;
+        positiveSlippageFeeTransformer: number;
     };
 
     private readonly _exchangeProxy: IZeroExContract;
@@ -92,6 +95,10 @@ export class ExchangeProxySwapQuoteConsumer implements SwapQuoteConsumerBase {
                 contractAddresses.transformers.affiliateFeeTransformer,
                 contractAddresses.exchangeProxyTransformerDeployer,
             ),
+            positiveSlippageFeeTransformer: findTransformerNonce(
+                contractAddresses.transformers.positiveSlippageFeeTransformer,
+                contractAddresses.exchangeProxyTransformerDeployer,
+            ),
         };
     }
 
@@ -117,7 +124,6 @@ export class ExchangeProxySwapQuoteConsumer implements SwapQuoteConsumerBase {
         if (isFromETH) {
             ethAmount = ethAmount.plus(sellAmount);
         }
-        const { buyTokenFeeAmount, sellTokenFeeAmount, recipient: feeRecipient } = affiliateFee;
 
         // VIP routes.
         if (
@@ -144,7 +150,8 @@ export class ExchangeProxySwapQuoteConsumer implements SwapQuoteConsumerBase {
                     .getABIEncodedTransactionData(),
                 ethAmount: isFromETH ? sellAmount : ZERO_AMOUNT,
                 toAddress: this._exchangeProxy.address,
-                allowanceTarget: this.contractAddresses.exchangeProxyAllowanceTarget,
+                allowanceTarget: this._exchangeProxy.address,
+                gasOverhead: ZERO_AMOUNT,
             };
         }
 
@@ -165,7 +172,8 @@ export class ExchangeProxySwapQuoteConsumer implements SwapQuoteConsumerBase {
                     .getABIEncodedTransactionData(),
                 ethAmount: isFromETH ? sellAmount : ZERO_AMOUNT,
                 toAddress: this._exchangeProxy.address,
-                allowanceTarget: this.contractAddresses.exchangeProxyAllowanceTarget,
+                allowanceTarget: this._exchangeProxy.address,
+                gasOverhead: ZERO_AMOUNT,
             };
         }
 
@@ -190,7 +198,8 @@ export class ExchangeProxySwapQuoteConsumer implements SwapQuoteConsumerBase {
                     .getABIEncodedTransactionData(),
                 ethAmount: isFromETH ? sellAmount : ZERO_AMOUNT,
                 toAddress: this._exchangeProxy.address,
-                allowanceTarget: this.contractAddresses.exchangeProxyAllowanceTarget,
+                allowanceTarget: this._exchangeProxy.address,
+                gasOverhead: ZERO_AMOUNT,
             };
         }
 
@@ -262,25 +271,52 @@ export class ExchangeProxySwapQuoteConsumer implements SwapQuoteConsumerBase {
             });
         }
 
-        // This transformer pays affiliate fees.
-        if (buyTokenFeeAmount.isGreaterThan(0) && feeRecipient !== NULL_ADDRESS) {
+        const { feeType, buyTokenFeeAmount, sellTokenFeeAmount, recipient: feeRecipient } = affiliateFee;
+        let gasOverhead = ZERO_AMOUNT;
+        if (feeType === AffiliateFeeType.PositiveSlippageFee && feeRecipient !== NULL_ADDRESS) {
+            // bestCaseAmountWithSurplus is used to cover gas cost of sending positive slipapge fee to fee recipient
+            // this helps avoid sending dust amounts which are not worth the gas cost to transfer
+            let bestCaseAmountWithSurplus = quote.bestCaseQuoteInfo.makerAmount
+                .plus(
+                    POSITIVE_SLIPPAGE_FEE_TRANSFORMER_GAS.multipliedBy(quote.gasPrice).multipliedBy(
+                        quote.makerAmountPerEth,
+                    ),
+                )
+                .integerValue();
+            // In the event makerAmountPerEth is unknown, we only allow for positive slippage which is greater than
+            // the best case amount
+            bestCaseAmountWithSurplus = BigNumber.max(bestCaseAmountWithSurplus, quote.bestCaseQuoteInfo.makerAmount);
             transforms.push({
-                deploymentNonce: this.transformerNonces.affiliateFeeTransformer,
-                data: encodeAffiliateFeeTransformerData({
-                    fees: [
-                        {
-                            token: isToETH ? ETH_TOKEN_ADDRESS : buyToken,
-                            amount: buyTokenFeeAmount,
-                            recipient: feeRecipient,
-                        },
-                    ],
+                deploymentNonce: this.transformerNonces.positiveSlippageFeeTransformer,
+                data: encodePositiveSlippageFeeTransformerData({
+                    token: isToETH ? ETH_TOKEN_ADDRESS : buyToken,
+                    bestCaseAmount: BigNumber.max(bestCaseAmountWithSurplus, quote.bestCaseQuoteInfo.makerAmount),
+                    recipient: feeRecipient,
                 }),
             });
-            // Adjust the minimum buy amount by the fee.
-            minBuyAmount = BigNumber.max(0, minBuyAmount.minus(buyTokenFeeAmount));
-        }
-        if (sellTokenFeeAmount.isGreaterThan(0) && feeRecipient !== NULL_ADDRESS) {
-            throw new Error('Affiliate fees denominated in sell token are not yet supported');
+            // This may not be visible at eth_estimateGas time, so we explicitly add overhead
+            gasOverhead = POSITIVE_SLIPPAGE_FEE_TRANSFORMER_GAS;
+        } else if (feeType === AffiliateFeeType.PercentageFee && feeRecipient !== NULL_ADDRESS) {
+            // This transformer pays affiliate fees.
+            if (buyTokenFeeAmount.isGreaterThan(0)) {
+                transforms.push({
+                    deploymentNonce: this.transformerNonces.affiliateFeeTransformer,
+                    data: encodeAffiliateFeeTransformerData({
+                        fees: [
+                            {
+                                token: isToETH ? ETH_TOKEN_ADDRESS : buyToken,
+                                amount: buyTokenFeeAmount,
+                                recipient: feeRecipient,
+                            },
+                        ],
+                    }),
+                });
+                // Adjust the minimum buy amount by the fee.
+                minBuyAmount = BigNumber.max(0, minBuyAmount.minus(buyTokenFeeAmount));
+            }
+            if (sellTokenFeeAmount.isGreaterThan(0)) {
+                throw new Error('Affiliate fees denominated in sell token are not yet supported');
+            }
         }
 
         // The final transformer will send all funds to the taker.
@@ -306,7 +342,8 @@ export class ExchangeProxySwapQuoteConsumer implements SwapQuoteConsumerBase {
             calldataHexString,
             ethAmount,
             toAddress: this._exchangeProxy.address,
-            allowanceTarget: this.contractAddresses.exchangeProxyAllowanceTarget,
+            allowanceTarget: this._exchangeProxy.address,
+            gasOverhead,
         };
     }
 
@@ -332,6 +369,10 @@ function isDirectSwapCompatible(
     if (!opts.affiliateFee.buyTokenFeeAmount.eq(0) || !opts.affiliateFee.sellTokenFeeAmount.eq(0)) {
         return false;
     }
+    // Must not have a positive slippage fee.
+    if (opts.affiliateFee.feeType === AffiliateFeeType.PositiveSlippageFee) {
+        return false;
+    }
     // Must be a single order.
     if (quote.orders.length !== 1) {
         return false;
diff --git a/packages/asset-swapper/src/swap_quoter.ts b/packages/asset-swapper/src/swap_quoter.ts
index a4acc64b84..6518a4ed93 100644
--- a/packages/asset-swapper/src/swap_quoter.ts
+++ b/packages/asset-swapper/src/swap_quoter.ts
@@ -454,7 +454,7 @@ function createSwapQuote(
     gasSchedule: FeeSchedule,
     slippage: number,
 ): SwapQuote {
-    const { optimizedOrders, quoteReport, sourceFlags, takerTokenToEthRate, makerTokenToEthRate } = optimizerResult;
+    const { optimizedOrders, quoteReport, sourceFlags, takerAmountPerEth, makerAmountPerEth } = optimizerResult;
     const isTwoHop = sourceFlags === SOURCE_FLAGS[ERC20BridgeSource.MultiHop];
 
     // Calculate quote info
@@ -474,8 +474,8 @@ function createSwapQuote(
         sourceBreakdown,
         makerTokenDecimals,
         takerTokenDecimals,
-        takerTokenToEthRate,
-        makerTokenToEthRate,
+        takerAmountPerEth,
+        makerAmountPerEth,
         quoteReport,
         isTwoHop,
     };
diff --git a/packages/asset-swapper/src/types.ts b/packages/asset-swapper/src/types.ts
index f4f0d38ec7..ea4657ab5f 100644
--- a/packages/asset-swapper/src/types.ts
+++ b/packages/asset-swapper/src/types.ts
@@ -54,12 +54,15 @@ export interface NativeOrderFillableAmountFields {
  * toAddress: The contract address to call.
  * ethAmount: The eth amount in wei to send with the smart contract call.
  * allowanceTarget: The address the taker should grant an allowance to.
+ * gasOverhead: The gas overhead needed to be added to the gas limit to allow for optional
+ * operations which may not visible at eth_estimateGas time
  */
 export interface CalldataInfo {
     calldataHexString: string;
     toAddress: string;
     ethAmount: BigNumber;
     allowanceTarget: string;
+    gasOverhead: BigNumber;
 }
 
 /**
@@ -98,7 +101,14 @@ export interface SwapQuoteExecutionOpts extends SwapQuoteGetOutputOpts {
     gasLimit?: number;
 }
 
-export interface AffiliateFee {
+export enum AffiliateFeeType {
+    None,
+    PercentageFee,
+    PositiveSlippageFee,
+}
+
+export interface AffiliateFeeAmount {
+    feeType: AffiliateFeeType;
     recipient: string;
     buyTokenFeeAmount: BigNumber;
     sellTokenFeeAmount: BigNumber;
@@ -130,7 +140,7 @@ export enum ExchangeProxyRefundReceiver {
 export interface ExchangeProxyContractOpts {
     isFromETH: boolean;
     isToETH: boolean;
-    affiliateFee: AffiliateFee;
+    affiliateFee: AffiliateFeeAmount;
     refundReceiver: string | ExchangeProxyRefundReceiver;
     isMetaTransaction: boolean;
     shouldSellEntireBalance: boolean;
@@ -161,8 +171,8 @@ export interface SwapQuoteBase {
     isTwoHop: boolean;
     makerTokenDecimals: number;
     takerTokenDecimals: number;
-    takerTokenToEthRate: BigNumber;
-    makerTokenToEthRate: BigNumber;
+    takerAmountPerEth: BigNumber;
+    makerAmountPerEth: BigNumber;
 }
 
 /**
diff --git a/packages/asset-swapper/src/utils/market_operation_utils/comparison_price.ts b/packages/asset-swapper/src/utils/market_operation_utils/comparison_price.ts
index fa12f78fb2..a88c6ed756 100644
--- a/packages/asset-swapper/src/utils/market_operation_utils/comparison_price.ts
+++ b/packages/asset-swapper/src/utils/market_operation_utils/comparison_price.ts
@@ -60,10 +60,10 @@ export function getComparisonPrices(
     }
 
     // Calc native order fee penalty in output unit (maker units for sells, taker unit for buys)
-    const feePenalty = !marketSideLiquidity.ethToOutputRate.isZero()
-        ? marketSideLiquidity.ethToOutputRate.times(feeInEth)
+    const feePenalty = !marketSideLiquidity.outputAmountPerEth.isZero()
+        ? marketSideLiquidity.outputAmountPerEth.times(feeInEth)
         : // if it's a sell, the input token is the taker token
-          marketSideLiquidity.ethToInputRate
+          marketSideLiquidity.inputAmountPerEth
               .times(feeInEth)
               .times(marketSideLiquidity.side === MarketOperation.Sell ? adjustedRate : adjustedRate.pow(-1));
 
diff --git a/packages/asset-swapper/src/utils/market_operation_utils/constants.ts b/packages/asset-swapper/src/utils/market_operation_utils/constants.ts
index 5b8d7ac8cb..8ce3acf478 100644
--- a/packages/asset-swapper/src/utils/market_operation_utils/constants.ts
+++ b/packages/asset-swapper/src/utils/market_operation_utils/constants.ts
@@ -645,6 +645,8 @@ export const DEFAULT_GAS_SCHEDULE: Required<FeeSchedule> = {
 
 export const DEFAULT_FEE_SCHEDULE: Required<FeeSchedule> = { ...DEFAULT_GAS_SCHEDULE };
 
+export const POSITIVE_SLIPPAGE_FEE_TRANSFORMER_GAS = new BigNumber(20000);
+
 // tslint:enable:custom-no-magic-numbers
 
 export const DEFAULT_GET_MARKET_ORDERS_OPTS: GetMarketOrdersOpts = {
diff --git a/packages/asset-swapper/src/utils/market_operation_utils/fills.ts b/packages/asset-swapper/src/utils/market_operation_utils/fills.ts
index 74a4515b9a..e097d0b08a 100644
--- a/packages/asset-swapper/src/utils/market_operation_utils/fills.ts
+++ b/packages/asset-swapper/src/utils/market_operation_utils/fills.ts
@@ -16,8 +16,8 @@ export function createFills(opts: {
     orders?: NativeOrderWithFillableAmounts[];
     dexQuotes?: DexSample[][];
     targetInput?: BigNumber;
-    ethToOutputRate?: BigNumber;
-    ethToInputRate?: BigNumber;
+    outputAmountPerEth?: BigNumber;
+    inputAmountPerEth?: BigNumber;
     excludedSources?: ERC20BridgeSource[];
     feeSchedule?: FeeSchedule;
 }): Fill[][] {
@@ -26,20 +26,20 @@ export function createFills(opts: {
     const feeSchedule = opts.feeSchedule || {};
     const orders = opts.orders || [];
     const dexQuotes = opts.dexQuotes || [];
-    const ethToOutputRate = opts.ethToOutputRate || ZERO_AMOUNT;
-    const ethToInputRate = opts.ethToInputRate || ZERO_AMOUNT;
+    const outputAmountPerEth = opts.outputAmountPerEth || ZERO_AMOUNT;
+    const inputAmountPerEth = opts.inputAmountPerEth || ZERO_AMOUNT;
     // Create native fills.
     const nativeFills = nativeOrdersToFills(
         side,
         orders.filter(o => o.fillableTakerAmount.isGreaterThan(0)),
         opts.targetInput,
-        ethToOutputRate,
-        ethToInputRate,
+        outputAmountPerEth,
+        inputAmountPerEth,
         feeSchedule,
     );
     // Create DEX fills.
     const dexFills = dexQuotes.map(singleSourceSamples =>
-        dexSamplesToFills(side, singleSourceSamples, ethToOutputRate, ethToInputRate, feeSchedule),
+        dexSamplesToFills(side, singleSourceSamples, outputAmountPerEth, inputAmountPerEth, feeSchedule),
     );
     return [...dexFills, nativeFills]
         .map(p => clipFillsToInput(p, opts.targetInput))
@@ -75,8 +75,8 @@ function nativeOrdersToFills(
     side: MarketOperation,
     orders: NativeOrderWithFillableAmounts[],
     targetInput: BigNumber = POSITIVE_INF,
-    ethToOutputRate: BigNumber,
-    ethToInputRate: BigNumber,
+    outputAmountPerEth: BigNumber,
+    inputAmountPerEth: BigNumber,
     fees: FeeSchedule,
 ): Fill[] {
     const sourcePathId = hexUtils.random();
@@ -89,9 +89,9 @@ function nativeOrdersToFills(
         const input = side === MarketOperation.Sell ? takerAmount : makerAmount;
         const output = side === MarketOperation.Sell ? makerAmount : takerAmount;
         const fee = fees[ERC20BridgeSource.Native] === undefined ? 0 : fees[ERC20BridgeSource.Native]!(o);
-        const outputPenalty = !ethToOutputRate.isZero()
-            ? ethToOutputRate.times(fee)
-            : ethToInputRate.times(fee).times(output.dividedToIntegerBy(input));
+        const outputPenalty = !outputAmountPerEth.isZero()
+            ? outputAmountPerEth.times(fee)
+            : inputAmountPerEth.times(fee).times(output.dividedToIntegerBy(input));
         // targetInput can be less than the order size
         // whilst the penalty is constant, it affects the adjusted output
         // only up until the target has been exhausted.
@@ -135,8 +135,8 @@ function nativeOrdersToFills(
 function dexSamplesToFills(
     side: MarketOperation,
     samples: DexSample[],
-    ethToOutputRate: BigNumber,
-    ethToInputRate: BigNumber,
+    outputAmountPerEth: BigNumber,
+    inputAmountPerEth: BigNumber,
     fees: FeeSchedule,
 ): Fill[] {
     const sourcePathId = hexUtils.random();
@@ -156,9 +156,9 @@ function dexSamplesToFills(
         let penalty = ZERO_AMOUNT;
         if (i === 0) {
             // Only the first fill in a DEX path incurs a penalty.
-            penalty = !ethToOutputRate.isZero()
-                ? ethToOutputRate.times(fee)
-                : ethToInputRate.times(fee).times(output.dividedToIntegerBy(input));
+            penalty = !outputAmountPerEth.isZero()
+                ? outputAmountPerEth.times(fee)
+                : inputAmountPerEth.times(fee).times(output.dividedToIntegerBy(input));
         }
         const adjustedOutput = side === MarketOperation.Sell ? output.minus(penalty) : output.plus(penalty);
 
diff --git a/packages/asset-swapper/src/utils/market_operation_utils/index.ts b/packages/asset-swapper/src/utils/market_operation_utils/index.ts
index fd1b905285..c9a473e6ed 100644
--- a/packages/asset-swapper/src/utils/market_operation_utils/index.ts
+++ b/packages/asset-swapper/src/utils/market_operation_utils/index.ts
@@ -30,7 +30,8 @@ import {
 import { createFills } from './fills';
 import { getBestTwoHopQuote } from './multihop_utils';
 import { createOrdersFromTwoHopSample } from './orders';
-import { findOptimalPathAsync } from './path_optimizer';
+import { PathPenaltyOpts } from './path';
+import { fillsToSortedPaths, findOptimalPathAsync } from './path_optimizer';
 import { DexOrderSampler, getSampleAmounts } from './sampler';
 import { SourceFilters } from './source_filters';
 import {
@@ -167,8 +168,8 @@ export class MarketOperationUtils {
             [
                 tokenDecimals,
                 orderFillableTakerAmounts,
-                ethToMakerAssetRate,
-                ethToTakerAssetRate,
+                outputAmountPerEth,
+                inputAmountPerEth,
                 dexQuotes,
                 rawTwoHopQuotes,
                 isTxOriginContract,
@@ -195,8 +196,8 @@ export class MarketOperationUtils {
             inputAmount: takerAmount,
             inputToken: takerToken,
             outputToken: makerToken,
-            ethToOutputRate: ethToMakerAssetRate,
-            ethToInputRate: ethToTakerAssetRate,
+            outputAmountPerEth,
+            inputAmountPerEth,
             quoteSourceFilters,
             makerTokenDecimals: makerTokenDecimals.toNumber(),
             takerTokenDecimals: takerTokenDecimals.toNumber(),
@@ -321,8 +322,8 @@ export class MarketOperationUtils {
             inputAmount: makerAmount,
             inputToken: makerToken,
             outputToken: takerToken,
-            ethToOutputRate: ethToTakerAssetRate,
-            ethToInputRate: ethToMakerAssetRate,
+            outputAmountPerEth: ethToTakerAssetRate,
+            inputAmountPerEth: ethToMakerAssetRate,
             quoteSourceFilters,
             makerTokenDecimals: makerTokenDecimals.toNumber(),
             takerTokenDecimals: takerTokenDecimals.toNumber(),
@@ -392,7 +393,7 @@ export class MarketOperationUtils {
         const batchEthToTakerAssetRate = executeResults.splice(0, batchNativeOrders.length) as BigNumber[];
         const batchDexQuotes = executeResults.splice(0, batchNativeOrders.length) as DexSample[][][];
         const batchTokenDecimals = executeResults.splice(0, batchNativeOrders.length) as number[][];
-        const ethToInputRate = ZERO_AMOUNT;
+        const inputAmountPerEth = ZERO_AMOUNT;
 
         return Promise.all(
             batchNativeOrders.map(async (nativeOrders, i) => {
@@ -401,7 +402,7 @@ export class MarketOperationUtils {
                 }
                 const { makerToken, takerToken } = nativeOrders[0].order;
                 const orderFillableMakerAmounts = batchOrderFillableMakerAmounts[i];
-                const ethToTakerAssetRate = batchEthToTakerAssetRate[i];
+                const outputAmountPerEth = batchEthToTakerAssetRate[i];
                 const dexQuotes = batchDexQuotes[i];
                 const makerAmount = makerAmounts[i];
                 try {
@@ -411,8 +412,8 @@ export class MarketOperationUtils {
                             inputToken: makerToken,
                             outputToken: takerToken,
                             inputAmount: makerAmount,
-                            ethToOutputRate: ethToTakerAssetRate,
-                            ethToInputRate,
+                            outputAmountPerEth,
+                            inputAmountPerEth,
                             quoteSourceFilters,
                             makerTokenDecimals: batchTokenDecimals[i][0],
                             takerTokenDecimals: batchTokenDecimals[i][1],
@@ -455,8 +456,8 @@ export class MarketOperationUtils {
             side,
             inputAmount,
             quotes,
-            ethToOutputRate,
-            ethToInputRate,
+            outputAmountPerEth,
+            inputAmountPerEth,
         } = marketSideLiquidity;
         const { nativeOrders, rfqtIndicativeQuotes, dexQuotes } = quotes;
         const maxFallbackSlippage = opts.maxFallbackSlippage || 0;
@@ -489,25 +490,29 @@ export class MarketOperationUtils {
             orders: [...nativeOrders, ...augmentedRfqtIndicativeQuotes],
             dexQuotes,
             targetInput: inputAmount,
-            ethToOutputRate,
-            ethToInputRate,
+            outputAmountPerEth,
+            inputAmountPerEth,
             excludedSources: opts.excludedSources,
             feeSchedule: opts.feeSchedule,
         });
 
         // Find the optimal path.
-        const optimizerOpts = {
-            ethToOutputRate,
-            ethToInputRate,
+        const penaltyOpts: PathPenaltyOpts = {
+            outputAmountPerEth,
+            inputAmountPerEth,
             exchangeProxyOverhead: opts.exchangeProxyOverhead || (() => ZERO_AMOUNT),
         };
 
         // NOTE: For sell quotes input is the taker asset and for buy quotes input is the maker asset
-        const takerTokenToEthRate = side === MarketOperation.Sell ? ethToInputRate : ethToOutputRate;
-        const makerTokenToEthRate = side === MarketOperation.Sell ? ethToOutputRate : ethToInputRate;
+        const takerAmountPerEth = side === MarketOperation.Sell ? inputAmountPerEth : outputAmountPerEth;
+        const makerAmountPerEth = side === MarketOperation.Sell ? outputAmountPerEth : inputAmountPerEth;
+
+        // Find the unoptimized best rate to calculate savings from optimizer
+        const _unoptimizedPath = fillsToSortedPaths(fills, side, inputAmount, penaltyOpts)[0];
+        const unoptimizedPath = _unoptimizedPath ? _unoptimizedPath.collapse(orderOpts) : undefined;
 
         // Find the optimal path
-        const optimalPath = await findOptimalPathAsync(side, fills, inputAmount, opts.runLimit, optimizerOpts);
+        const optimalPath = await findOptimalPathAsync(side, fills, inputAmount, opts.runLimit, penaltyOpts);
         const optimalPathRate = optimalPath ? optimalPath.adjustedRate() : ZERO_AMOUNT;
 
         const { adjustedRate: bestTwoHopRate, quote: bestTwoHopQuote } = getBestTwoHopQuote(
@@ -523,8 +528,9 @@ export class MarketOperationUtils {
                 sourceFlags: SOURCE_FLAGS[ERC20BridgeSource.MultiHop],
                 marketSideLiquidity,
                 adjustedRate: bestTwoHopRate,
-                takerTokenToEthRate,
-                makerTokenToEthRate,
+                unoptimizedPath,
+                takerAmountPerEth,
+                makerAmountPerEth,
             };
         }
 
@@ -557,8 +563,9 @@ export class MarketOperationUtils {
             sourceFlags: collapsedPath.sourceFlags,
             marketSideLiquidity,
             adjustedRate: optimalPathRate,
-            takerTokenToEthRate,
-            makerTokenToEthRate,
+            unoptimizedPath,
+            takerAmountPerEth,
+            makerAmountPerEth,
         };
     }
 
diff --git a/packages/asset-swapper/src/utils/market_operation_utils/multihop_utils.ts b/packages/asset-swapper/src/utils/market_operation_utils/multihop_utils.ts
index 6b064fd159..5f8bf98465 100644
--- a/packages/asset-swapper/src/utils/market_operation_utils/multihop_utils.ts
+++ b/packages/asset-swapper/src/utils/market_operation_utils/multihop_utils.ts
@@ -39,7 +39,7 @@ export function getBestTwoHopQuote(
     feeSchedule?: FeeSchedule,
     exchangeProxyOverhead?: ExchangeProxyOverhead,
 ): { quote: DexSample<MultiHopFillData> | undefined; adjustedRate: BigNumber } {
-    const { side, inputAmount, ethToOutputRate, quotes } = marketSideLiquidity;
+    const { side, inputAmount, outputAmountPerEth, quotes } = marketSideLiquidity;
     const { twoHopQuotes } = quotes;
     // Ensure the expected data we require exists. In the case where all hops reverted
     // or there were no sources included that allowed for multi hop,
@@ -57,7 +57,7 @@ export function getBestTwoHopQuote(
     }
     const best = filteredQuotes
         .map(quote =>
-            getTwoHopAdjustedRate(side, quote, inputAmount, ethToOutputRate, feeSchedule, exchangeProxyOverhead),
+            getTwoHopAdjustedRate(side, quote, inputAmount, outputAmountPerEth, feeSchedule, exchangeProxyOverhead),
         )
         .reduce(
             (prev, curr, i) =>
@@ -67,7 +67,7 @@ export function getBestTwoHopQuote(
                     side,
                     filteredQuotes[0],
                     inputAmount,
-                    ethToOutputRate,
+                    outputAmountPerEth,
                     feeSchedule,
                     exchangeProxyOverhead,
                 ),
diff --git a/packages/asset-swapper/src/utils/market_operation_utils/path.ts b/packages/asset-swapper/src/utils/market_operation_utils/path.ts
index 5788c0a73b..11182eb07a 100644
--- a/packages/asset-swapper/src/utils/market_operation_utils/path.ts
+++ b/packages/asset-swapper/src/utils/market_operation_utils/path.ts
@@ -22,14 +22,14 @@ export interface PathSize {
 }
 
 export interface PathPenaltyOpts {
-    ethToOutputRate: BigNumber;
-    ethToInputRate: BigNumber;
+    outputAmountPerEth: BigNumber;
+    inputAmountPerEth: BigNumber;
     exchangeProxyOverhead: ExchangeProxyOverhead;
 }
 
 export const DEFAULT_PATH_PENALTY_OPTS: PathPenaltyOpts = {
-    ethToOutputRate: ZERO_AMOUNT,
-    ethToInputRate: ZERO_AMOUNT,
+    outputAmountPerEth: ZERO_AMOUNT,
+    inputAmountPerEth: ZERO_AMOUNT,
     exchangeProxyOverhead: () => ZERO_AMOUNT,
 };
 
@@ -131,11 +131,11 @@ export class Path {
 
     public adjustedSize(): PathSize {
         const { input, output } = this._adjustedSize;
-        const { exchangeProxyOverhead, ethToOutputRate, ethToInputRate } = this.pathPenaltyOpts;
+        const { exchangeProxyOverhead, outputAmountPerEth, inputAmountPerEth } = this.pathPenaltyOpts;
         const gasOverhead = exchangeProxyOverhead(this.sourceFlags);
-        const pathPenalty = !ethToOutputRate.isZero()
-            ? ethToOutputRate.times(gasOverhead)
-            : ethToInputRate.times(gasOverhead).times(output.dividedToIntegerBy(input));
+        const pathPenalty = !outputAmountPerEth.isZero()
+            ? outputAmountPerEth.times(gasOverhead)
+            : inputAmountPerEth.times(gasOverhead).times(output.dividedToIntegerBy(input));
         return {
             input,
             output: this.side === MarketOperation.Sell ? output.minus(pathPenalty) : output.plus(pathPenalty),
diff --git a/packages/asset-swapper/src/utils/market_operation_utils/rate_utils.ts b/packages/asset-swapper/src/utils/market_operation_utils/rate_utils.ts
index 43d007b623..bc2a0207b1 100644
--- a/packages/asset-swapper/src/utils/market_operation_utils/rate_utils.ts
+++ b/packages/asset-swapper/src/utils/market_operation_utils/rate_utils.ts
@@ -13,7 +13,7 @@ export function getTwoHopAdjustedRate(
     side: MarketOperation,
     twoHopQuote: DexSample<MultiHopFillData>,
     targetInput: BigNumber,
-    ethToOutputRate: BigNumber,
+    outputAmountPerEth: BigNumber,
     fees: FeeSchedule = {},
     exchangeProxyOverhead: ExchangeProxyOverhead = () => ZERO_AMOUNT,
 ): BigNumber {
@@ -21,7 +21,7 @@ export function getTwoHopAdjustedRate(
     if (input.isLessThan(targetInput) || output.isZero()) {
         return ZERO_AMOUNT;
     }
-    const penalty = ethToOutputRate.times(
+    const penalty = outputAmountPerEth.times(
         exchangeProxyOverhead(SOURCE_FLAGS.MultiHop).plus(fees[ERC20BridgeSource.MultiHop]!(fillData)),
     );
     const adjustedOutput = side === MarketOperation.Sell ? output.minus(penalty) : output.plus(penalty);
diff --git a/packages/asset-swapper/src/utils/market_operation_utils/types.ts b/packages/asset-swapper/src/utils/market_operation_utils/types.ts
index 9266b5c8ab..1008b63650 100644
--- a/packages/asset-swapper/src/utils/market_operation_utils/types.ts
+++ b/packages/asset-swapper/src/utils/market_operation_utils/types.ts
@@ -11,6 +11,7 @@ import { NativeOrderWithFillableAmounts, RfqtFirmQuoteValidator, RfqtRequestOpts
 import { QuoteRequestor } from '../../utils/quote_requestor';
 import { QuoteReport } from '../quote_report_generator';
 
+import { CollapsedPath } from './path';
 import { SourceFilters } from './source_filters';
 
 /**
@@ -374,8 +375,9 @@ export interface OptimizerResult {
     liquidityDelivered: CollapsedFill[] | DexSample<MultiHopFillData>;
     marketSideLiquidity: MarketSideLiquidity;
     adjustedRate: BigNumber;
-    takerTokenToEthRate: BigNumber;
-    makerTokenToEthRate: BigNumber;
+    unoptimizedPath?: CollapsedPath;
+    takerAmountPerEth: BigNumber;
+    makerAmountPerEth: BigNumber;
 }
 
 export interface OptimizerResultWithReport extends OptimizerResult {
@@ -396,8 +398,8 @@ export interface MarketSideLiquidity {
     inputAmount: BigNumber;
     inputToken: string;
     outputToken: string;
-    ethToOutputRate: BigNumber;
-    ethToInputRate: BigNumber;
+    outputAmountPerEth: BigNumber;
+    inputAmountPerEth: BigNumber;
     quoteSourceFilters: SourceFilters;
     makerTokenDecimals: number;
     takerTokenDecimals: number;
diff --git a/packages/asset-swapper/test/comparison_price_test.ts b/packages/asset-swapper/test/comparison_price_test.ts
index de143c42bc..fe490cb5fa 100644
--- a/packages/asset-swapper/test/comparison_price_test.ts
+++ b/packages/asset-swapper/test/comparison_price_test.ts
@@ -49,8 +49,8 @@ const exchangeProxyOverhead = (sourceFlags: number) => {
 
 const buyMarketSideLiquidity: MarketSideLiquidity = {
     // needed params
-    ethToOutputRate: new BigNumber(500),
-    ethToInputRate: new BigNumber(1),
+    outputAmountPerEth: new BigNumber(500),
+    inputAmountPerEth: new BigNumber(1),
     side: MarketOperation.Buy,
     makerTokenDecimals: 18,
     takerTokenDecimals: 18,
@@ -70,8 +70,8 @@ const buyMarketSideLiquidity: MarketSideLiquidity = {
 
 const sellMarketSideLiquidity: MarketSideLiquidity = {
     // needed params
-    ethToOutputRate: new BigNumber(500),
-    ethToInputRate: new BigNumber(1),
+    outputAmountPerEth: new BigNumber(500),
+    inputAmountPerEth: new BigNumber(1),
     side: MarketOperation.Sell,
     makerTokenDecimals: 18,
     takerTokenDecimals: 18,
diff --git a/packages/asset-swapper/test/exchange_proxy_swap_quote_consumer_test.ts b/packages/asset-swapper/test/exchange_proxy_swap_quote_consumer_test.ts
index 120cca401a..62a2c337ea 100644
--- a/packages/asset-swapper/test/exchange_proxy_swap_quote_consumer_test.ts
+++ b/packages/asset-swapper/test/exchange_proxy_swap_quote_consumer_test.ts
@@ -4,6 +4,7 @@ import {
     decodeAffiliateFeeTransformerData,
     decodeFillQuoteTransformerData,
     decodePayTakerTransformerData,
+    decodePositiveSlippageFeeTransformerData,
     decodeWethTransformerData,
     ETH_TOKEN_ADDRESS,
     FillQuoteTransformerLimitOrderInfo,
@@ -17,9 +18,9 @@ import * as chai from 'chai';
 import * as _ from 'lodash';
 import 'mocha';
 
-import { constants } from '../src/constants';
+import { constants, POSITIVE_SLIPPAGE_FEE_TRANSFORMER_GAS } from '../src/constants';
 import { ExchangeProxySwapQuoteConsumer } from '../src/quote_consumers/exchange_proxy_swap_quote_consumer';
-import { MarketBuySwapQuote, MarketOperation, MarketSellSwapQuote } from '../src/types';
+import { AffiliateFeeType, MarketBuySwapQuote, MarketOperation, MarketSellSwapQuote } from '../src/types';
 import {
     ERC20BridgeSource,
     OptimizedLimitOrder,
@@ -53,6 +54,7 @@ describe('ExchangeProxySwapQuoteConsumer', () => {
             payTakerTransformer: getTransformerAddress(TRANSFORMER_DEPLOYER, 2),
             fillQuoteTransformer: getTransformerAddress(TRANSFORMER_DEPLOYER, 3),
             affiliateFeeTransformer: getTransformerAddress(TRANSFORMER_DEPLOYER, 4),
+            positiveSlippageFeeTransformer: getTransformerAddress(TRANSFORMER_DEPLOYER, 5),
         },
     };
     let consumer: ExchangeProxySwapQuoteConsumer;
@@ -137,11 +139,11 @@ describe('ExchangeProxySwapQuoteConsumer', () => {
                 protocolFeeInWeiAmount: getRandomAmount(),
                 feeTakerTokenAmount: getRandomAmount(),
             },
+            makerAmountPerEth: getRandomInteger(1, 1e9),
+            takerAmountPerEth: getRandomInteger(1, 1e9),
             ...(side === MarketOperation.Buy
                 ? { type: MarketOperation.Buy, makerTokenFillAmount }
                 : { type: MarketOperation.Sell, takerTokenFillAmount }),
-            takerTokenToEthRate: getRandomAmount(),
-            makerTokenToEthRate: getRandomAmount(),
         };
     }
 
@@ -336,6 +338,7 @@ describe('ExchangeProxySwapQuoteConsumer', () => {
                 recipient: randomAddress(),
                 buyTokenFeeAmount: getRandomAmount(),
                 sellTokenFeeAmount: ZERO_AMOUNT,
+                feeType: AffiliateFeeType.PercentageFee,
             };
             const callInfo = await consumer.getCalldataOrThrowAsync(quote, {
                 extensionContractOpts: { affiliateFee },
@@ -349,12 +352,42 @@ describe('ExchangeProxySwapQuoteConsumer', () => {
                 { token: MAKER_TOKEN, amount: affiliateFee.buyTokenFeeAmount, recipient: affiliateFee.recipient },
             ]);
         });
+        it('Appends a positive slippage affiliate fee transformer after the fill if the positive slippage fee feeType is specified', async () => {
+            const quote = getRandomSellQuote();
+            const affiliateFee = {
+                recipient: randomAddress(),
+                buyTokenFeeAmount: ZERO_AMOUNT,
+                sellTokenFeeAmount: ZERO_AMOUNT,
+                feeType: AffiliateFeeType.PositiveSlippageFee,
+            };
+            const callInfo = await consumer.getCalldataOrThrowAsync(quote, {
+                extensionContractOpts: { affiliateFee },
+            });
+            const callArgs = transformERC20Encoder.decode(callInfo.calldataHexString) as TransformERC20Args;
+            expect(callArgs.transformations[1].deploymentNonce.toNumber()).to.eq(
+                consumer.transformerNonces.positiveSlippageFeeTransformer,
+            );
+            const positiveSlippageFeeTransformerData = decodePositiveSlippageFeeTransformerData(
+                callArgs.transformations[1].data,
+            );
+            const bestCaseAmount = quote.bestCaseQuoteInfo.makerAmount.plus(
+                POSITIVE_SLIPPAGE_FEE_TRANSFORMER_GAS.multipliedBy(quote.gasPrice).multipliedBy(
+                    quote.makerAmountPerEth,
+                ),
+            );
+            expect(positiveSlippageFeeTransformerData).to.deep.equal({
+                token: MAKER_TOKEN,
+                bestCaseAmount,
+                recipient: affiliateFee.recipient,
+            });
+        });
         it('Throws if a sell token affiliate fee is provided', async () => {
             const quote = getRandomSellQuote();
             const affiliateFee = {
                 recipient: randomAddress(),
                 buyTokenFeeAmount: ZERO_AMOUNT,
                 sellTokenFeeAmount: getRandomAmount(),
+                feeType: AffiliateFeeType.PercentageFee,
             };
             expect(
                 consumer.getCalldataOrThrowAsync(quote, {
diff --git a/packages/asset-swapper/test/market_operation_utils_test.ts b/packages/asset-swapper/test/market_operation_utils_test.ts
index 5a0f7490a9..9d1cf34c41 100644
--- a/packages/asset-swapper/test/market_operation_utils_test.ts
+++ b/packages/asset-swapper/test/market_operation_utils_test.ts
@@ -756,8 +756,8 @@ describe('MarketOperationUtils tests', () => {
                             inputAmount: Web3Wrapper.toBaseUnitAmount(1, 18),
                             inputToken: MAKER_TOKEN,
                             outputToken: TAKER_TOKEN,
-                            ethToInputRate: Web3Wrapper.toBaseUnitAmount(1, 18),
-                            ethToOutputRate: Web3Wrapper.toBaseUnitAmount(1, 6),
+                            inputAmountPerEth: Web3Wrapper.toBaseUnitAmount(1, 18),
+                            outputAmountPerEth: Web3Wrapper.toBaseUnitAmount(1, 6),
                             quoteSourceFilters: new SourceFilters(),
                             makerTokenDecimals: 6,
                             takerTokenDecimals: 18,
@@ -1787,7 +1787,7 @@ describe('MarketOperationUtils tests', () => {
 
     describe('createFills', () => {
         const takerAmount = new BigNumber(5000000);
-        const ethToOutputRate = new BigNumber(0.5);
+        const outputAmountPerEth = new BigNumber(0.5);
         // tslint:disable-next-line:no-object-literal-type-assertion
         const smallOrder: NativeOrderWithFillableAmounts = {
             order: {
@@ -1830,7 +1830,7 @@ describe('MarketOperationUtils tests', () => {
                 orders,
                 dexQuotes: [],
                 targetInput: takerAmount.minus(1),
-                ethToOutputRate,
+                outputAmountPerEth,
                 feeSchedule,
             });
             expect((path[0][0].fillData as NativeFillData).order.maker).to.eq(smallOrder.order.maker);
@@ -1843,7 +1843,7 @@ describe('MarketOperationUtils tests', () => {
                 orders,
                 dexQuotes: [],
                 targetInput: POSITIVE_INF,
-                ethToOutputRate,
+                outputAmountPerEth,
                 feeSchedule,
             });
             expect((path[0][0].fillData as NativeFillData).order.maker).to.eq(largeOrder.order.maker);
diff --git a/packages/asset-swapper/test/utils/swap_quote.ts b/packages/asset-swapper/test/utils/swap_quote.ts
index 6e0d174d12..ac5edc8432 100644
--- a/packages/asset-swapper/test/utils/swap_quote.ts
+++ b/packages/asset-swapper/test/utils/swap_quote.ts
@@ -39,8 +39,8 @@ export async function getFullyFillableSwapQuoteWithNoFeesAsync(
         worstCaseQuoteInfo: quoteInfo,
         sourceBreakdown: breakdown,
         isTwoHop: false,
-        takerTokenToEthRate: constants.ZERO_AMOUNT,
-        makerTokenToEthRate: constants.ZERO_AMOUNT,
+        takerAmountPerEth: constants.ZERO_AMOUNT,
+        makerAmountPerEth: constants.ZERO_AMOUNT,
         makerTokenDecimals: 18,
         takerTokenDecimals: 18,
     };
diff --git a/packages/contract-addresses/CHANGELOG.json b/packages/contract-addresses/CHANGELOG.json
index 3e2cb9d41b..b706f4b475 100644
--- a/packages/contract-addresses/CHANGELOG.json
+++ b/packages/contract-addresses/CHANGELOG.json
@@ -5,6 +5,10 @@
             {
                 "note": "Deploy new FQT",
                 "pr": 155
+            },
+            {
+                "note": "Deploy new `PositiveSlippageFeeTransformer`",
+                "pr": 101
             }
         ]
     },
diff --git a/packages/contract-addresses/addresses.json b/packages/contract-addresses/addresses.json
index 5035e9dab7..b78f7860d3 100644
--- a/packages/contract-addresses/addresses.json
+++ b/packages/contract-addresses/addresses.json
@@ -37,7 +37,8 @@
             "wethTransformer": "0xb2bc06a4efb20fc6553a69dbfa49b7be938034a7",
             "payTakerTransformer": "0x4638a7ebe75b911b995d0ec73a81e4f85f41f24e",
             "affiliateFeeTransformer": "0xda6d9fc5998f550a094585cf9171f0e8ee3ac59f",
-            "fillQuoteTransformer": "0x227e767a9b7517681d1cb6b846aa9e541484c7ab"
+            "fillQuoteTransformer": "0x227e767a9b7517681d1cb6b846aa9e541484c7ab",
+            "positiveSlippageFeeTransformer": "0xa9416ce1dbde8d331210c07b5c253d94ee4cc3fd"
         }
     },
     "3": {
@@ -78,7 +79,8 @@
             "wethTransformer": "0x05ad19aa3826e0609a19568ffbd1dfe86c6c7184",
             "payTakerTransformer": "0x6d0ebf2bcd9cc93ec553b60ad201943dcca4e291",
             "affiliateFeeTransformer": "0x6588256778ca4432fa43983ac685c45efb2379e2",
-            "fillQuoteTransformer": "0x2088a820787ebbe937a0612ef024f1e1d65f9784"
+            "fillQuoteTransformer": "0x2088a820787ebbe937a0612ef024f1e1d65f9784",
+            "positiveSlippageFeeTransformer": "0x8b332f700fd37e71c5c5b26c4d78b5ca63dd33b2"
         }
     },
     "4": {
@@ -119,7 +121,8 @@
             "wethTransformer": "0x8d822fe2b42f60531203e288f5f357fa79474437",
             "payTakerTransformer": "0x150652244723102faeaefa4c79597d097ffa26c6",
             "affiliateFeeTransformer": "0xa39b40642e8e00435857a0fe7d0655e08cc2217e",
-            "fillQuoteTransformer": "0x3fb85e0c1e9e0ba4ba9a4072442a2540c0473db1"
+            "fillQuoteTransformer": "0x3fb85e0c1e9e0ba4ba9a4072442a2540c0473db1",
+            "positiveSlippageFeeTransformer": "0x0000000000000000000000000000000000000000"
         }
     },
     "42": {
@@ -160,7 +163,8 @@
             "wethTransformer": "0x9ce35b5ee9e710535e3988e3f8731d9ca9dba17d",
             "payTakerTransformer": "0x5a53e7b02a83aa9f60ccf4e424f0442c255bc977",
             "affiliateFeeTransformer": "0x870893920a96a28d4b63c0a7d06a521e3bd074b3",
-            "fillQuoteTransformer": "0x8d2d732e5fe6d4d6d5e715200b84dfa69fb05478"
+            "fillQuoteTransformer": "0x8d2d732e5fe6d4d6d5e715200b84dfa69fb05478",
+            "positiveSlippageFeeTransformer": "0x0000000000000000000000000000000000000000"
         }
     },
     "1337": {
@@ -201,7 +205,8 @@
             "wethTransformer": "0x7209185959d7227fb77274e1e88151d7c4c368d3",
             "payTakerTransformer": "0x3f16ca81691dab9184cb4606c361d73c4fd2510a",
             "affiliateFeeTransformer": "0x99356167edba8fbdc36959e3f5d0c43d1ba9c6db",
-            "fillQuoteTransformer": "0x45b3a72221e571017c0f0ec42189e11d149d0ace"
+            "fillQuoteTransformer": "0x45b3a72221e571017c0f0ec42189e11d149d0ace",
+            "positiveSlippageFeeTransformer": "0xdd66c23e07b4d6925b6089b5fe6fc9e62941afe8"
         }
     }
 }
diff --git a/packages/contract-addresses/src/index.ts b/packages/contract-addresses/src/index.ts
index 5ce4b0d738..dc8f07e8ca 100644
--- a/packages/contract-addresses/src/index.ts
+++ b/packages/contract-addresses/src/index.ts
@@ -39,6 +39,7 @@ export interface ContractAddresses {
         payTakerTransformer: string;
         fillQuoteTransformer: string;
         affiliateFeeTransformer: string;
+        positiveSlippageFeeTransformer: string;
     };
 }
 
diff --git a/packages/migrations/src/migration.ts b/packages/migrations/src/migration.ts
index 886380448c..b9d54c64ec 100644
--- a/packages/migrations/src/migration.ts
+++ b/packages/migrations/src/migration.ts
@@ -32,6 +32,7 @@ import {
     FillQuoteTransformerContract,
     fullMigrateAsync as fullMigrateExchangeProxyAsync,
     PayTakerTransformerContract,
+    PositiveSlippageFeeTransformerContract,
     WethTransformerContract,
 } from '@0x/contracts-zero-ex';
 import { Web3ProviderEngine } from '@0x/subproviders';
@@ -345,7 +346,12 @@ export async function runMigrationsAsync(
         bridgeAdapter.address,
         exchangeProxy.address,
     );
-
+    const positiveSlippageFeeTransformer = await PositiveSlippageFeeTransformerContract.deployFrom0xArtifactAsync(
+        exchangeProxyArtifacts.PositiveSlippageFeeTransformer,
+        provider,
+        txDefaults,
+        allArtifacts,
+    );
     const contractAddresses = {
         erc20Proxy: erc20Proxy.address,
         erc721Proxy: erc721Proxy.address,
@@ -385,6 +391,7 @@ export async function runMigrationsAsync(
             payTakerTransformer: payTakerTransformer.address,
             fillQuoteTransformer: fillQuoteTransformer.address,
             affiliateFeeTransformer: affiliateFeeTransformer.address,
+            positiveSlippageFeeTransformer: positiveSlippageFeeTransformer.address,
         },
     };
     return contractAddresses;
diff --git a/packages/order-utils/src/index.ts b/packages/order-utils/src/index.ts
index 6a54e31604..d8f1e458d5 100644
--- a/packages/order-utils/src/index.ts
+++ b/packages/order-utils/src/index.ts
@@ -77,6 +77,9 @@ export {
     AffiliateFeeTransformerData,
     encodeAffiliateFeeTransformerData,
     decodeAffiliateFeeTransformerData,
+    PositiveSlippageFeeTransformerData,
+    encodePositiveSlippageFeeTransformerData,
+    decodePositiveSlippageFeeTransformerData,
     findTransformerNonce,
     getTransformerAddress,
 } from './transformer_utils';
diff --git a/packages/order-utils/src/transformer_utils.ts b/packages/order-utils/src/transformer_utils.ts
index 9bdd93b67b..60ad6f00fc 100644
--- a/packages/order-utils/src/transformer_utils.ts
+++ b/packages/order-utils/src/transformer_utils.ts
@@ -152,7 +152,7 @@ export function decodePayTakerTransformerData(encoded: string): PayTakerTransfor
 }
 
 /**
- * ABI encoder for `PayTakerTransformer.TransformData`
+ * ABI encoder for `affiliateFeetransformer.TransformData`
  */
 export const affiliateFeeTransformerDataEncoder = AbiEncoder.create({
     name: 'data',
@@ -195,6 +195,42 @@ export function decodeAffiliateFeeTransformerData(encoded: string): AffiliateFee
     return affiliateFeeTransformerDataEncoder.decode(encoded);
 }
 
+/**
+ * ABI encoder for `PositiveSlippageFeeTransformer.TransformData`
+ */
+export const positiveSlippageFeeTransformerDataEncoder = AbiEncoder.create({
+    name: 'data',
+    type: 'tuple',
+    components: [
+        { name: 'token', type: 'address' },
+        { name: 'bestCaseAmount', type: 'uint256' },
+        { name: 'recipient', type: 'address' },
+    ],
+});
+
+/**
+ * `PositiveSlippageFeeTransformer.TransformData`
+ */
+export interface PositiveSlippageFeeTransformerData {
+    token: string;
+    bestCaseAmount: BigNumber;
+    recipient: string;
+}
+
+/**
+ * ABI-encode a `PositiveSlippageFeeTransformer.TransformData` type.
+ */
+export function encodePositiveSlippageFeeTransformerData(data: PositiveSlippageFeeTransformerData): string {
+    return positiveSlippageFeeTransformerDataEncoder.encode(data);
+}
+
+/**
+ * ABI-decode a `PositiveSlippageFeeTransformer.TransformData` type.
+ */
+export function decodePositiveSlippageFeeTransformerData(encoded: string): PositiveSlippageFeeTransformerData {
+    return positiveSlippageFeeTransformerDataEncoder.decode(encoded);
+}
+
 /**
  * Find the nonce for a transformer given its deployer.
  * If `deployer` is the null address, zero will always be returned.
diff --git a/packages/protocol-utils/src/transformer_utils.ts b/packages/protocol-utils/src/transformer_utils.ts
index febad1284e..c9aa84e85f 100644
--- a/packages/protocol-utils/src/transformer_utils.ts
+++ b/packages/protocol-utils/src/transformer_utils.ts
@@ -242,7 +242,7 @@ export function decodePayTakerTransformerData(encoded: string): PayTakerTransfor
 }
 
 /**
- * ABI encoder for `PayTakerTransformer.TransformData`
+ * ABI encoder for `affiliateFeetransformer.TransformData`
  */
 export const affiliateFeeTransformerDataEncoder = AbiEncoder.create({
     name: 'data',
@@ -317,3 +317,39 @@ export function getTransformerAddress(deployer: string, nonce: number): string {
         ethjs.rlphash([deployer, nonce] as any).slice(12),
     );
 }
+
+/**
+ * ABI encoder for `PositiveSlippageFeeTransformer.TransformData`
+ */
+export const positiveSlippageFeeTransformerDataEncoder = AbiEncoder.create({
+    name: 'data',
+    type: 'tuple',
+    components: [
+        { name: 'token', type: 'address' },
+        { name: 'bestCaseAmount', type: 'uint256' },
+        { name: 'recipient', type: 'address' },
+    ],
+});
+
+/**
+ * `PositiveSlippageFeeTransformer.TransformData`
+ */
+export interface PositiveSlippageFeeTransformerData {
+    token: string;
+    bestCaseAmount: BigNumber;
+    recipient: string;
+}
+
+/**
+ * ABI-encode a `PositiveSlippageFeeTransformer.TransformData` type.
+ */
+export function encodePositiveSlippageFeeTransformerData(data: PositiveSlippageFeeTransformerData): string {
+    return positiveSlippageFeeTransformerDataEncoder.encode(data);
+}
+
+/**
+ * ABI-decode a `PositiveSlippageFeeTransformer.TransformData` type.
+ */
+export function decodePositiveSlippageFeeTransformerData(encoded: string): PositiveSlippageFeeTransformerData {
+    return positiveSlippageFeeTransformerDataEncoder.decode(encoded);
+}