diff --git a/mev_inspect/traces.py b/mev_inspect/traces.py
index 29c8acd..792897e 100644
--- a/mev_inspect/traces.py
+++ b/mev_inspect/traces.py
@@ -1,9 +1,26 @@
+from itertools import groupby
 from typing import Iterable, List
 
 from mev_inspect.schemas import Trace, NestedTrace
 
 
 def as_nested_traces(traces: Iterable[Trace]) -> List[NestedTrace]:
+    nested_traces = []
+
+    sorted_by_transaction_hash = sorted(traces, key=_get_transaction_hash)
+    for _, transaction_traces in groupby(
+        sorted_by_transaction_hash, _get_transaction_hash
+    ):
+        nested_traces += _as_nested_traces_by_transaction(transaction_traces)
+
+    return nested_traces
+
+
+def _get_transaction_hash(trace) -> str:
+    return trace.transaction_hash
+
+
+def _as_nested_traces_by_transaction(traces: Iterable[Trace]) -> List[NestedTrace]:
     """
     Turns a list of Traces into a a tree of NestedTraces
     using their trace addresses
diff --git a/tests/trace_test.py b/tests/trace_test.py
index 24af48f..dd415aa 100644
--- a/tests/trace_test.py
+++ b/tests/trace_test.py
@@ -10,29 +10,38 @@ DEFAULT_BLOCK_NUMBER = 123
 
 class TestTraces(unittest.TestCase):
     def test_nested_traces(self):
-        trace_addresses = [
-            [0, 2],
-            [],
-            [2],
-            [0],
-            [0, 0],
-            [0, 1],
-            [1],
-            [1, 0],
-            [0, 1, 0],
+        trace_hash_address_pairs = [
+            ("abc", [0, 2]),
+            ("abc", []),
+            ("abc", [2]),
+            ("abc", [0]),
+            ("abc", [0, 0]),
+            ("abc", [0, 1]),
+            ("abc", [1]),
+            ("efg", []),
+            ("abc", [1, 0]),
+            ("abc", [0, 1, 0]),
+            ("efg", [0]),
         ]
 
-        traces = [build_trace_at_address(address) for address in trace_addresses]
+        traces = [
+            build_trace_at_address(hash, address)
+            for (hash, address) in trace_hash_address_pairs
+        ]
 
         nested_traces = as_nested_traces(traces)
 
-        assert len(nested_traces) == 1
-        root_trace = nested_traces[0]
+        assert len(nested_traces) == 2
 
-        assert_trace_address(root_trace, [])
-        assert len(root_trace.subtraces) == 3
+        abc_trace = nested_traces[0]
+        efg_trace = nested_traces[1]
 
-        [trace_0, trace_1, trace_2] = root_trace.subtraces
+        # abc
+        assert abc_trace.trace.transaction_hash == "abc"
+        assert_trace_address(abc_trace, [])
+        assert len(abc_trace.subtraces) == 3
+
+        [trace_0, trace_1, trace_2] = abc_trace.subtraces
 
         assert_trace_address(trace_0, [0])
         assert_trace_address(trace_1, [1])
@@ -59,15 +68,26 @@ class TestTraces(unittest.TestCase):
         assert_trace_address(trace_0_1_0, [0, 1, 0])
         assert len(trace_0_1_0.subtraces) == 0
 
+        # efg
+        assert efg_trace.trace.transaction_hash == "efg"
+        assert_trace_address(efg_trace, [])
+        assert len(efg_trace.subtraces) == 1
+
+        [efg_subtrace] = efg_trace.subtraces
+
+        assert_trace_address(efg_subtrace, [0])
+        assert len(efg_subtrace.subtraces) == 0
+
 
 def build_trace_at_address(
+    transaction_hash: str,
     trace_address: List[int],
 ) -> Trace:
     return Trace(
         # real values
+        transaction_hash=transaction_hash,
         trace_address=trace_address,
         # placeholders
-        transaction_hash="",
         action={},
         block_hash="",
         block_number=DEFAULT_BLOCK_NUMBER,