diff --git a/tests/unit/simulation/__init__.py b/tests/unit/simulation/__init__.py
new file mode 100644
index 00000000..e792b96d
--- /dev/null
+++ b/tests/unit/simulation/__init__.py
@@ -0,0 +1 @@
+"""Unit tests for the simulation module."""
diff --git a/tests/unit/simulation/test_scenario_runner.py b/tests/unit/simulation/test_scenario_runner.py
new file mode 100644
index 00000000..f5e9a924
--- /dev/null
+++ b/tests/unit/simulation/test_scenario_runner.py
@@ -0,0 +1,835 @@
+"""Tests for Scenario Runner.
+
+Issue #33: [SIM-32] Scenario runner - parallel portfolio simulations
+
+Tests cover:
+- ExecutionMode and ScenarioStatus enums
+- ScenarioConfig and ScenarioResult dataclasses
+- ScenarioRunner sequential execution
+- ScenarioRunner parallel execution
+- Progress tracking and callbacks
+- ScenarioBatchBuilder variations
+- Result aggregation
+- Error handling
+- Cancellation
+"""
+
+import pytest
+import time
+from datetime import datetime, date
+from decimal import Decimal
+from unittest.mock import Mock, patch
+import threading
+
+from tradingagents.simulation.scenario_runner import (
+    ExecutionMode,
+    ScenarioStatus,
+    ScenarioConfig,
+    ScenarioResult,
+    RunnerProgress,
+    ScenarioRunner,
+    ScenarioBatchBuilder,
+    aggregate_results,
+)
+
+
+# ==============================================================================
+# ExecutionMode Enum Tests
+# ==============================================================================
+
+
+class TestExecutionMode:
+    """Tests for ExecutionMode enum."""
+
+    def test_sequential_value(self):
+        """Test SEQUENTIAL mode value."""
+        assert ExecutionMode.SEQUENTIAL.value == "sequential"
+
+    def test_threaded_value(self):
+        """Test THREADED mode value."""
+        assert ExecutionMode.THREADED.value == "threaded"
+
+    def test_process_value(self):
+        """Test PROCESS mode value."""
+        assert ExecutionMode.PROCESS.value == "process"
+
+    def test_all_modes_exist(self):
+        """Test all expected modes exist."""
+        modes = [m for m in ExecutionMode]
+        assert len(modes) == 3
+
+
+# ==============================================================================
+# ScenarioStatus Enum Tests
+# ==============================================================================
+
+
+class TestScenarioStatus:
+    """Tests for ScenarioStatus enum."""
+
+    def test_pending_value(self):
+        """Test PENDING status value."""
+        assert ScenarioStatus.PENDING.value == "pending"
+
+    def test_running_value(self):
+        """Test RUNNING status value."""
+        assert ScenarioStatus.RUNNING.value == "running"
+
+    def test_completed_value(self):
+        """Test COMPLETED status value."""
+        assert ScenarioStatus.COMPLETED.value == "completed"
+
+    def test_failed_value(self):
+        """Test FAILED status value."""
+        assert ScenarioStatus.FAILED.value == "failed"
+
+    def test_cancelled_value(self):
+        """Test CANCELLED status value."""
+        assert ScenarioStatus.CANCELLED.value == "cancelled"
+
+    def test_all_statuses_exist(self):
+        """Test all expected statuses exist."""
+        statuses = [s for s in ScenarioStatus]
+        assert len(statuses) == 5
+
+
+# ==============================================================================
+# ScenarioConfig Tests
+# ==============================================================================
+
+
+class TestScenarioConfig:
+    """Tests for ScenarioConfig dataclass."""
+
+    def test_default_config(self):
+        """Test creating config with defaults."""
+        config = ScenarioConfig()
+        assert config.scenario_id is not None
+        assert config.name.startswith("Scenario-")
+        assert config.initial_capital == Decimal("100000")
+        assert config.symbols == []
+        assert config.strategy_params == {}
+        assert config.risk_params == {}
+
+    def test_custom_config(self):
+        """Test creating config with custom values."""
+        config = ScenarioConfig(
+            name="Bull Market Test",
+            start_date=date(2023, 1, 1),
+            end_date=date(2023, 12, 31),
+            initial_capital=Decimal("50000"),
+            symbols=["AAPL", "GOOGL"],
+            strategy_params={"leverage": 1.5},
+            risk_params={"max_drawdown": 0.2},
+        )
+        assert config.name == "Bull Market Test"
+        assert config.start_date == date(2023, 1, 1)
+        assert config.end_date == date(2023, 12, 31)
+        assert config.initial_capital == Decimal("50000")
+        assert config.symbols == ["AAPL", "GOOGL"]
+        assert config.strategy_params["leverage"] == 1.5
+        assert config.risk_params["max_drawdown"] == 0.2
+
+    def test_auto_generated_name(self):
+        """Test auto-generated name from scenario_id."""
+        config = ScenarioConfig()
+        # Name should start with "Scenario-" and contain part of the ID
+        assert config.name.startswith("Scenario-")
+        assert len(config.name) > 8
+
+    def test_explicit_scenario_id(self):
+        """Test explicit scenario ID."""
+        config = ScenarioConfig(scenario_id="test-123")
+        assert config.scenario_id == "test-123"
+
+
+# ==============================================================================
+# ScenarioResult Tests
+# ==============================================================================
+
+
+class TestScenarioResult:
+    """Tests for ScenarioResult dataclass."""
+
+    def test_successful_result(self):
+        """Test creating a successful result."""
+        result = ScenarioResult(
+            scenario_id="test-1",
+            scenario_name="Test",
+            status=ScenarioStatus.COMPLETED,
+            start_time=datetime.now(),
+            final_value=Decimal("110000"),
+            total_return=Decimal("0.10"),
+        )
+        assert result.is_successful is True
+        assert result.is_finished is True
+
+    def test_failed_result(self):
+        """Test creating a failed result."""
+        result = ScenarioResult(
+            scenario_id="test-1",
+            scenario_name="Test",
+            status=ScenarioStatus.FAILED,
+            start_time=datetime.now(),
+            error_message="Simulation error",
+        )
+        assert result.is_successful is False
+        assert result.is_finished is True
+        assert result.error_message == "Simulation error"
+
+    def test_pending_result(self):
+        """Test pending result properties."""
+        result = ScenarioResult(
+            scenario_id="test-1",
+            scenario_name="Test",
+            status=ScenarioStatus.PENDING,
+            start_time=datetime.now(),
+        )
+        assert result.is_successful is False
+        assert result.is_finished is False
+
+    def test_running_result(self):
+        """Test running result properties."""
+        result = ScenarioResult(
+            scenario_id="test-1",
+            scenario_name="Test",
+            status=ScenarioStatus.RUNNING,
+            start_time=datetime.now(),
+        )
+        assert result.is_successful is False
+        assert result.is_finished is False
+
+    def test_cancelled_result(self):
+        """Test cancelled result properties."""
+        result = ScenarioResult(
+            scenario_id="test-1",
+            scenario_name="Test",
+            status=ScenarioStatus.CANCELLED,
+            start_time=datetime.now(),
+        )
+        assert result.is_successful is False
+        assert result.is_finished is True
+
+
+# ==============================================================================
+# RunnerProgress Tests
+# ==============================================================================
+
+
+class TestRunnerProgress:
+    """Tests for RunnerProgress dataclass."""
+
+    def test_progress_percent(self):
+        """Test progress percentage calculation."""
+        progress = RunnerProgress(
+            total_scenarios=10,
+            completed=3,
+            failed=2,
+        )
+        assert progress.progress_percent == 50.0
+
+    def test_progress_percent_zero_total(self):
+        """Test progress with zero total scenarios."""
+        progress = RunnerProgress(total_scenarios=0)
+        assert progress.progress_percent == 100.0
+
+    def test_is_complete(self):
+        """Test completion detection."""
+        progress = RunnerProgress(
+            total_scenarios=5,
+            completed=3,
+            failed=2,
+        )
+        assert progress.is_complete is True
+
+    def test_not_complete(self):
+        """Test incomplete detection."""
+        progress = RunnerProgress(
+            total_scenarios=5,
+            completed=2,
+            failed=1,
+        )
+        assert progress.is_complete is False
+
+
+# ==============================================================================
+# ScenarioRunner Tests - Sequential Execution
+# ==============================================================================
+
+
+class TestScenarioRunnerSequential:
+    """Tests for ScenarioRunner sequential execution."""
+
+    def test_run_empty_list(self):
+        """Test running with empty scenario list."""
+        def executor(config):
+            return ScenarioResult(
+                scenario_id=config.scenario_id,
+                scenario_name=config.name,
+                status=ScenarioStatus.COMPLETED,
+                start_time=datetime.now(),
+            )
+
+        runner = ScenarioRunner(executor=executor, mode=ExecutionMode.SEQUENTIAL)
+        results = runner.run([])
+        assert results == []
+
+    def test_run_single_scenario(self):
+        """Test running a single scenario."""
+        def executor(config):
+            return ScenarioResult(
+                scenario_id=config.scenario_id,
+                scenario_name=config.name,
+                status=ScenarioStatus.COMPLETED,
+                start_time=datetime.now(),
+                final_value=Decimal("110000"),
+                total_return=Decimal("0.10"),
+            )
+
+        runner = ScenarioRunner(executor=executor, mode=ExecutionMode.SEQUENTIAL)
+        scenarios = [ScenarioConfig(name="Test1")]
+        results = runner.run(scenarios)
+
+        assert len(results) == 1
+        assert results[0].is_successful
+        assert results[0].scenario_name == "Test1"
+
+    def test_run_multiple_scenarios(self):
+        """Test running multiple scenarios sequentially."""
+        call_order = []
+
+        def executor(config):
+            call_order.append(config.name)
+            return ScenarioResult(
+                scenario_id=config.scenario_id,
+                scenario_name=config.name,
+                status=ScenarioStatus.COMPLETED,
+                start_time=datetime.now(),
+            )
+
+        runner = ScenarioRunner(executor=executor, mode=ExecutionMode.SEQUENTIAL)
+        scenarios = [
+            ScenarioConfig(name="Test1"),
+            ScenarioConfig(name="Test2"),
+            ScenarioConfig(name="Test3"),
+        ]
+        results = runner.run(scenarios)
+
+        assert len(results) == 3
+        assert call_order == ["Test1", "Test2", "Test3"]
+        assert all(r.is_successful for r in results)
+
+    def test_run_with_executor_exception(self):
+        """Test handling executor exceptions."""
+        def executor(config):
+            if config.name == "FailMe":
+                raise ValueError("Simulated error")
+            return ScenarioResult(
+                scenario_id=config.scenario_id,
+                scenario_name=config.name,
+                status=ScenarioStatus.COMPLETED,
+                start_time=datetime.now(),
+            )
+
+        runner = ScenarioRunner(executor=executor, mode=ExecutionMode.SEQUENTIAL)
+        scenarios = [
+            ScenarioConfig(name="Test1"),
+            ScenarioConfig(name="FailMe"),
+            ScenarioConfig(name="Test3"),
+        ]
+        results = runner.run(scenarios)
+
+        assert len(results) == 3
+        assert results[0].is_successful
+        assert results[1].status == ScenarioStatus.FAILED
+        assert "Simulated error" in results[1].error_message
+        assert results[2].is_successful
+
+
+# ==============================================================================
+# ScenarioRunner Tests - Parallel Execution
+# ==============================================================================
+
+
+class TestScenarioRunnerParallel:
+    """Tests for ScenarioRunner parallel execution."""
+
+    def test_run_threaded(self):
+        """Test running scenarios in parallel using threads."""
+        def executor(config):
+            time.sleep(0.01)  # Small delay to ensure parallelism
+            return ScenarioResult(
+                scenario_id=config.scenario_id,
+                scenario_name=config.name,
+                status=ScenarioStatus.COMPLETED,
+                start_time=datetime.now(),
+            )
+
+        runner = ScenarioRunner(
+            executor=executor,
+            mode=ExecutionMode.THREADED,
+            max_workers=4,
+        )
+        scenarios = [ScenarioConfig(name=f"Test{i}") for i in range(8)]
+
+        start = time.time()
+        results = runner.run(scenarios)
+        elapsed = time.time() - start
+
+        assert len(results) == 8
+        assert all(r.is_successful for r in results)
+        # With 4 workers and 8 scenarios at 0.01s each,
+        # parallel should be faster than sequential (0.08s)
+        # Allow some overhead
+        assert elapsed < 0.1
+
+    def test_results_order_preserved(self):
+        """Test that results match input order."""
+        import random
+
+        def executor(config):
+            # Random delay to encourage out-of-order completion
+            time.sleep(random.uniform(0.001, 0.01))
+            return ScenarioResult(
+                scenario_id=config.scenario_id,
+                scenario_name=config.name,
+                status=ScenarioStatus.COMPLETED,
+                start_time=datetime.now(),
+                final_value=Decimal(config.metadata.get("index", 0)),
+            )
+
+        runner = ScenarioRunner(
+            executor=executor,
+            mode=ExecutionMode.THREADED,
+            max_workers=4,
+        )
+        scenarios = [
+            ScenarioConfig(name=f"Test{i}", metadata={"index": i})
+            for i in range(10)
+        ]
+        results = runner.run(scenarios)
+
+        assert len(results) == 10
+        for i, result in enumerate(results):
+            assert result.scenario_name == f"Test{i}"
+            assert result.final_value == Decimal(i)
+
+
+# ==============================================================================
+# ScenarioRunner Tests - Progress Tracking
+# ==============================================================================
+
+
+class TestScenarioRunnerProgress:
+    """Tests for ScenarioRunner progress tracking."""
+
+    def test_progress_callback(self):
+        """Test progress callback invocation."""
+        progress_updates = []
+
+        def on_progress(progress):
+            progress_updates.append({
+                "completed": progress.completed,
+                "total": progress.total_scenarios,
+            })
+
+        def executor(config):
+            return ScenarioResult(
+                scenario_id=config.scenario_id,
+                scenario_name=config.name,
+                status=ScenarioStatus.COMPLETED,
+                start_time=datetime.now(),
+            )
+
+        runner = ScenarioRunner(executor=executor, mode=ExecutionMode.SEQUENTIAL)
+        scenarios = [ScenarioConfig(name=f"Test{i}") for i in range(3)]
+        runner.run(scenarios, progress_callback=on_progress)
+
+        # Should have received progress updates
+        assert len(progress_updates) > 0
+        # Final update should show all completed
+        final = progress_updates[-1]
+        assert final["completed"] == 3
+
+    def test_get_progress(self):
+        """Test get_progress method."""
+        def executor(config):
+            time.sleep(0.01)
+            return ScenarioResult(
+                scenario_id=config.scenario_id,
+                scenario_name=config.name,
+                status=ScenarioStatus.COMPLETED,
+                start_time=datetime.now(),
+            )
+
+        runner = ScenarioRunner(
+            executor=executor,
+            mode=ExecutionMode.THREADED,
+            max_workers=2,
+        )
+
+        scenarios = [ScenarioConfig(name=f"Test{i}") for i in range(4)]
+
+        # Start in background
+        results = []
+        def run_in_thread():
+            nonlocal results
+            results = runner.run(scenarios)
+
+        thread = threading.Thread(target=run_in_thread)
+        thread.start()
+
+        # Give it time to start
+        time.sleep(0.005)
+        progress = runner.get_progress()
+        assert progress.total_scenarios == 4
+
+        thread.join()
+        assert len(results) == 4
+
+
+# ==============================================================================
+# ScenarioRunner Tests - Cancellation
+# ==============================================================================
+
+
+class TestScenarioRunnerCancellation:
+    """Tests for ScenarioRunner cancellation."""
+
+    def test_cancel_pending_scenarios(self):
+        """Test cancelling pending scenarios."""
+        executed = []
+
+        def executor(config):
+            executed.append(config.name)
+            time.sleep(0.02)
+            return ScenarioResult(
+                scenario_id=config.scenario_id,
+                scenario_name=config.name,
+                status=ScenarioStatus.COMPLETED,
+                start_time=datetime.now(),
+            )
+
+        runner = ScenarioRunner(
+            executor=executor,
+            mode=ExecutionMode.SEQUENTIAL,
+        )
+
+        scenarios = [ScenarioConfig(name=f"Test{i}") for i in range(5)]
+
+        # Cancel after short delay
+        def cancel_after_delay():
+            time.sleep(0.03)
+            runner.cancel()
+
+        cancel_thread = threading.Thread(target=cancel_after_delay)
+        cancel_thread.start()
+
+        results = runner.run(scenarios)
+        cancel_thread.join()
+
+        # Some should be completed, some cancelled
+        completed = [r for r in results if r.status == ScenarioStatus.COMPLETED]
+        cancelled = [r for r in results if r.status == ScenarioStatus.CANCELLED]
+
+        assert len(completed) + len(cancelled) == 5
+        # At least the first one should have completed
+        assert len(completed) >= 1
+
+
+# ==============================================================================
+# ScenarioBatchBuilder Tests
+# ==============================================================================
+
+
+class TestScenarioBatchBuilder:
+    """Tests for ScenarioBatchBuilder."""
+
+    def test_empty_build(self):
+        """Test building with no configuration."""
+        builder = ScenarioBatchBuilder()
+        scenarios = builder.build()
+        assert len(scenarios) == 1  # One default scenario
+
+    def test_base_config(self):
+        """Test setting base configuration."""
+        builder = ScenarioBatchBuilder()
+        scenarios = (
+            builder
+            .with_base_config(
+                initial_capital=Decimal("50000"),
+                symbols=["AAPL", "GOOGL"],
+            )
+            .build()
+        )
+        assert len(scenarios) == 1
+        assert scenarios[0].initial_capital == Decimal("50000")
+        assert scenarios[0].symbols == ["AAPL", "GOOGL"]
+
+    def test_parameter_variation(self):
+        """Test varying a single parameter."""
+        builder = ScenarioBatchBuilder()
+        scenarios = (
+            builder
+            .vary_parameter("leverage", [0.5, 1.0, 1.5])
+            .build()
+        )
+        assert len(scenarios) == 3
+        leverages = [s.strategy_params["leverage"] for s in scenarios]
+        assert leverages == [0.5, 1.0, 1.5]
+
+    def test_multiple_parameter_variations(self):
+        """Test varying multiple parameters (Cartesian product)."""
+        builder = ScenarioBatchBuilder()
+        scenarios = (
+            builder
+            .vary_parameter("leverage", [1.0, 2.0])
+            .vary_parameter("stop_loss", [0.05, 0.10])
+            .build()
+        )
+        assert len(scenarios) == 4  # 2 x 2
+
+        combinations = [
+            (s.strategy_params["leverage"], s.strategy_params["stop_loss"])
+            for s in scenarios
+        ]
+        expected = [
+            (1.0, 0.05),
+            (1.0, 0.10),
+            (2.0, 0.05),
+            (2.0, 0.10),
+        ]
+        assert sorted(combinations) == sorted(expected)
+
+    def test_explicit_date_ranges(self):
+        """Test setting explicit date ranges."""
+        builder = ScenarioBatchBuilder()
+        scenarios = (
+            builder
+            .with_date_ranges([
+                (date(2020, 1, 1), date(2020, 12, 31)),
+                (date(2021, 1, 1), date(2021, 12, 31)),
+            ])
+            .build()
+        )
+        assert len(scenarios) == 2
+        assert scenarios[0].start_date == date(2020, 1, 1)
+        assert scenarios[1].start_date == date(2021, 1, 1)
+
+    def test_clear_builder(self):
+        """Test clearing builder configuration."""
+        builder = ScenarioBatchBuilder()
+        builder.with_base_config(initial_capital=Decimal("50000"))
+        builder.vary_parameter("leverage", [1.0, 2.0])
+        builder.clear()
+
+        scenarios = builder.build()
+        assert len(scenarios) == 1
+        assert scenarios[0].initial_capital == Decimal("100000")  # Default
+
+    def test_scenario_names_generated(self):
+        """Test that scenario names are auto-generated."""
+        builder = ScenarioBatchBuilder()
+        scenarios = (
+            builder
+            .vary_parameter("leverage", [1.0, 2.0])
+            .build()
+        )
+        assert "leverage=1.0" in scenarios[0].name
+        assert "leverage=2.0" in scenarios[1].name
+
+
+# ==============================================================================
+# Result Aggregation Tests
+# ==============================================================================
+
+
+class TestResultAggregation:
+    """Tests for result aggregation."""
+
+    def test_aggregate_empty_results(self):
+        """Test aggregating empty results list."""
+        agg = aggregate_results([])
+        assert agg["total_scenarios"] == 0
+        assert agg["successful"] == 0
+        assert agg["failed"] == 0
+
+    def test_aggregate_successful_results(self):
+        """Test aggregating successful results."""
+        results = [
+            ScenarioResult(
+                scenario_id=f"test-{i}",
+                scenario_name=f"Test{i}",
+                status=ScenarioStatus.COMPLETED,
+                start_time=datetime.now(),
+                total_return=Decimal(f"0.{i+1}"),
+                max_drawdown=Decimal(f"-0.0{i+1}"),
+                duration_seconds=1.0,
+            )
+            for i in range(3)
+        ]
+
+        agg = aggregate_results(results)
+        assert agg["total_scenarios"] == 3
+        assert agg["successful"] == 3
+        assert agg["failed"] == 0
+        assert agg["success_rate"] == 1.0
+        assert "avg_return" in agg
+        assert "min_return" in agg
+        assert "max_return" in agg
+
+    def test_aggregate_mixed_results(self):
+        """Test aggregating mixed success/failure results."""
+        results = [
+            ScenarioResult(
+                scenario_id="test-1",
+                scenario_name="Success1",
+                status=ScenarioStatus.COMPLETED,
+                start_time=datetime.now(),
+                total_return=Decimal("0.10"),
+            ),
+            ScenarioResult(
+                scenario_id="test-2",
+                scenario_name="Failed1",
+                status=ScenarioStatus.FAILED,
+                start_time=datetime.now(),
+                error_message="Error",
+            ),
+            ScenarioResult(
+                scenario_id="test-3",
+                scenario_name="Success2",
+                status=ScenarioStatus.COMPLETED,
+                start_time=datetime.now(),
+                total_return=Decimal("0.20"),
+            ),
+        ]
+
+        agg = aggregate_results(results)
+        assert agg["total_scenarios"] == 3
+        assert agg["successful"] == 2
+        assert agg["failed"] == 1
+        assert agg["success_rate"] == pytest.approx(0.667, rel=0.01)
+
+    def test_aggregate_best_worst_scenarios(self):
+        """Test best/worst scenario identification."""
+        results = [
+            ScenarioResult(
+                scenario_id="test-1",
+                scenario_name="Low",
+                status=ScenarioStatus.COMPLETED,
+                start_time=datetime.now(),
+                total_return=Decimal("0.05"),
+            ),
+            ScenarioResult(
+                scenario_id="test-2",
+                scenario_name="High",
+                status=ScenarioStatus.COMPLETED,
+                start_time=datetime.now(),
+                total_return=Decimal("0.25"),
+            ),
+            ScenarioResult(
+                scenario_id="test-3",
+                scenario_name="Mid",
+                status=ScenarioStatus.COMPLETED,
+                start_time=datetime.now(),
+                total_return=Decimal("0.15"),
+            ),
+        ]
+
+        agg = aggregate_results(results)
+        assert agg["best_scenario"]["name"] == "High"
+        assert agg["worst_scenario"]["name"] == "Low"
+
+
+# ==============================================================================
+# Module Import Tests
+# ==============================================================================
+
+
+class TestModuleImports:
+    """Tests for module imports."""
+
+    def test_import_from_simulation_module(self):
+        """Test importing from simulation module."""
+        from tradingagents.simulation import (
+            ExecutionMode,
+            ScenarioStatus,
+            ScenarioConfig,
+            ScenarioResult,
+            RunnerProgress,
+            ScenarioRunner,
+            ScenarioBatchBuilder,
+            aggregate_results,
+        )
+        assert ExecutionMode is not None
+        assert ScenarioStatus is not None
+        assert ScenarioConfig is not None
+        assert ScenarioResult is not None
+        assert RunnerProgress is not None
+        assert ScenarioRunner is not None
+        assert ScenarioBatchBuilder is not None
+        assert aggregate_results is not None
+
+
+# ==============================================================================
+# Integration Tests
+# ==============================================================================
+
+
+class TestScenarioRunnerIntegration:
+    """Integration tests for ScenarioRunner."""
+
+    def test_full_simulation_workflow(self):
+        """Test complete simulation workflow."""
+        # Create executor that simulates trading
+        def trading_simulator(config: ScenarioConfig) -> ScenarioResult:
+            # Simulate based on strategy params
+            leverage = config.strategy_params.get("leverage", 1.0)
+            base_return = 0.08  # 8% base return
+            final_return = base_return * leverage
+
+            final_value = config.initial_capital * Decimal(str(1 + final_return))
+
+            return ScenarioResult(
+                scenario_id=config.scenario_id,
+                scenario_name=config.name,
+                status=ScenarioStatus.COMPLETED,
+                start_time=datetime.now(),
+                end_time=datetime.now(),
+                final_value=final_value.quantize(Decimal("0.01")),
+                total_return=Decimal(str(final_return)).quantize(Decimal("0.0001")),
+                max_drawdown=Decimal("-0.10"),
+                trades_executed=25,
+            )
+
+        # Build scenarios with varying leverage
+        scenarios = (
+            ScenarioBatchBuilder()
+            .with_base_config(initial_capital=Decimal("100000"))
+            .vary_parameter("leverage", [0.5, 1.0, 1.5, 2.0])
+            .build()
+        )
+
+        # Run simulations
+        runner = ScenarioRunner(
+            executor=trading_simulator,
+            mode=ExecutionMode.THREADED,
+            max_workers=4,
+        )
+
+        progress_updates = []
+        results = runner.run(
+            scenarios,
+            progress_callback=lambda p: progress_updates.append(p.completed),
+        )
+
+        # Verify results
+        assert len(results) == 4
+        assert all(r.is_successful for r in results)
+
+        # Aggregate and analyze
+        agg = aggregate_results(results)
+        assert agg["total_scenarios"] == 4
+        assert agg["successful"] == 4
+        assert agg["best_scenario"]["name"] == "leverage=2.0"
+        assert agg["worst_scenario"]["name"] == "leverage=0.5"
diff --git a/tradingagents/simulation/__init__.py b/tradingagents/simulation/__init__.py
new file mode 100644
index 00000000..0981dc3f
--- /dev/null
+++ b/tradingagents/simulation/__init__.py
@@ -0,0 +1,96 @@
+"""Simulation module for portfolio simulations and backtesting.
+
+This module provides simulation capabilities including:
+- Parallel scenario execution
+- Parameter sweep analysis
+- Strategy comparison
+- Economic regime simulation
+
+Issue #33: [SIM-32] Scenario runner - parallel portfolio simulations
+
+Submodules:
+    scenario_runner: Core scenario execution framework
+
+Classes:
+    Enums:
+    - ExecutionMode: Parallel execution mode (sequential, threaded, process)
+    - ScenarioStatus: Status of a scenario run
+
+    Data Classes:
+    - ScenarioConfig: Configuration for a simulation scenario
+    - ScenarioResult: Result from a scenario simulation
+    - RunnerProgress: Progress information for batch runs
+
+    Main Classes:
+    - ScenarioRunner: Runner for parallel portfolio simulations
+    - ScenarioBatchBuilder: Builder for creating scenario batches
+
+    Protocols:
+    - ScenarioExecutor: Protocol for scenario execution functions
+
+    Utility Functions:
+    - aggregate_results: Aggregate results from multiple scenarios
+
+Example:
+    >>> from tradingagents.simulation import (
+    ...     ScenarioRunner,
+    ...     ScenarioConfig,
+    ...     ScenarioResult,
+    ...     ScenarioStatus,
+    ...     ExecutionMode,
+    ... )
+    >>> from datetime import datetime
+    >>> from decimal import Decimal
+    >>>
+    >>> def simple_executor(config: ScenarioConfig) -> ScenarioResult:
+    ...     return ScenarioResult(
+    ...         scenario_id=config.scenario_id,
+    ...         scenario_name=config.name,
+    ...         status=ScenarioStatus.COMPLETED,
+    ...         start_time=datetime.now(),
+    ...         final_value=config.initial_capital * Decimal("1.1"),
+    ...         total_return=Decimal("0.1"),
+    ...     )
+    >>>
+    >>> runner = ScenarioRunner(executor=simple_executor)
+    >>> scenarios = [ScenarioConfig(name="Test1"), ScenarioConfig(name="Test2")]
+    >>> results = runner.run(scenarios)
+"""
+
+from .scenario_runner import (
+    # Enums
+    ExecutionMode,
+    ScenarioStatus,
+    # Data Classes
+    ScenarioConfig,
+    ScenarioResult,
+    RunnerProgress,
+    # Main Classes
+    ScenarioRunner,
+    ScenarioBatchBuilder,
+    # Protocols
+    ScenarioExecutor,
+    # Types
+    ProgressCallback,
+    # Utility Functions
+    aggregate_results,
+)
+
+__all__ = [
+    # Enums
+    "ExecutionMode",
+    "ScenarioStatus",
+    # Data Classes
+    "ScenarioConfig",
+    "ScenarioResult",
+    "RunnerProgress",
+    # Main Classes
+    "ScenarioRunner",
+    "ScenarioBatchBuilder",
+    # Protocols
+    "ScenarioExecutor",
+    # Types
+    "ProgressCallback",
+    # Utility Functions
+    "aggregate_results",
+]
diff --git a/tradingagents/simulation/scenario_runner.py b/tradingagents/simulation/scenario_runner.py
new file mode 100644
index 00000000..38de43fc
--- /dev/null
+++ b/tradingagents/simulation/scenario_runner.py
@@ -0,0 +1,689 @@
+"""Scenario Runner for parallel portfolio simulations.
+
+This module provides scenario-based simulation capabilities including:
+- Parallel execution of multiple portfolio scenarios
+- Configurable simulation parameters
+- Progress tracking and callbacks
+- Result aggregation and comparison
+
+Issue #33: [SIM-32] Scenario runner - parallel portfolio simulations
+
+Design Principles:
+    - Thread-safe parallel execution
+    - Configurable concurrency limits
+    - Memory-efficient result handling
+    - Progress reporting callbacks
+"""
+
+from concurrent.futures import ThreadPoolExecutor, ProcessPoolExecutor, as_completed
+from dataclasses import dataclass, field
+from datetime import datetime, date
+from decimal import Decimal
+from enum import Enum
+from typing import Any, Callable, Dict, List, Optional, Protocol, Tuple, Union
+import copy
+import threading
+import time
+import uuid
+
+
+class ExecutionMode(Enum):
+    """Mode of parallel execution."""
+    SEQUENTIAL = "sequential"    # Run scenarios one at a time
+    THREADED = "threaded"        # Use thread pool (for I/O bound)
+    PROCESS = "process"          # Use process pool (for CPU bound)
+
+
+class ScenarioStatus(Enum):
+    """Status of a scenario run."""
+    PENDING = "pending"          # Not yet started
+    RUNNING = "running"          # Currently executing
+    COMPLETED = "completed"      # Finished successfully
+    FAILED = "failed"            # Finished with error
+    CANCELLED = "cancelled"      # Cancelled before completion
+
+
+@dataclass
+class ScenarioConfig:
+    """Configuration for a simulation scenario.
+
+    Attributes:
+        scenario_id: Unique identifier for the scenario
+        name: Human-readable name
+        start_date: Simulation start date
+        end_date: Simulation end date
+        initial_capital: Starting capital
+        symbols: List of symbols to include
+        strategy_params: Strategy-specific parameters
+        risk_params: Risk management parameters
+        metadata: Additional scenario data
+    """
+    scenario_id: str = field(default_factory=lambda: str(uuid.uuid4()))
+    name: str = ""
+    start_date: Optional[date] = None
+    end_date: Optional[date] = None
+    initial_capital: Decimal = Decimal("100000")
+    symbols: List[str] = field(default_factory=list)
+    strategy_params: Dict[str, Any] = field(default_factory=dict)
+    risk_params: Dict[str, Any] = field(default_factory=dict)
+    metadata: Dict[str, Any] = field(default_factory=dict)
+
+    def __post_init__(self):
+        """Set default name if not provided."""
+        if not self.name:
+            self.name = f"Scenario-{self.scenario_id[:8]}"
+
+
+@dataclass
+class ScenarioResult:
+    """Result from a scenario simulation.
+
+    Attributes:
+        scenario_id: ID of the scenario that was run
+        scenario_name: Name of the scenario
+        status: Final status of the run
+        start_time: When simulation started
+        end_time: When simulation ended
+        duration_seconds: Total runtime in seconds
+        final_value: Final portfolio value
+        total_return: Total return as decimal (0.10 = 10%)
+        trades_executed: Number of trades made
+        max_drawdown: Maximum drawdown experienced
+        sharpe_ratio: Sharpe ratio if calculable
+        error_message: Error message if failed
+        portfolio_history: Time series of portfolio values
+        trade_history: List of trades executed
+        metrics: Additional performance metrics
+        metadata: Additional result data
+    """
+    scenario_id: str
+    scenario_name: str
+    status: ScenarioStatus
+    start_time: datetime
+    end_time: Optional[datetime] = None
+    duration_seconds: float = 0.0
+    final_value: Decimal = Decimal("0")
+    total_return: Decimal = Decimal("0")
+    trades_executed: int = 0
+    max_drawdown: Decimal = Decimal("0")
+    sharpe_ratio: Optional[Decimal] = None
+    error_message: Optional[str] = None
+    portfolio_history: List[Tuple[date, Decimal]] = field(default_factory=list)
+    trade_history: List[Dict[str, Any]] = field(default_factory=list)
+    metrics: Dict[str, Any] = field(default_factory=dict)
+    metadata: Dict[str, Any] = field(default_factory=dict)
+
+    @property
+    def is_successful(self) -> bool:
+        """Check if scenario completed successfully."""
+        return self.status == ScenarioStatus.COMPLETED
+
+    @property
+    def is_finished(self) -> bool:
+        """Check if scenario has finished (success or failure)."""
+        return self.status in (
+            ScenarioStatus.COMPLETED,
+            ScenarioStatus.FAILED,
+            ScenarioStatus.CANCELLED,
+        )
+
+
+class ScenarioExecutor(Protocol):
+    """Protocol for scenario execution functions.
+
+    Implementations should take a ScenarioConfig and return a ScenarioResult.
+    """
+
+    def __call__(self, config: ScenarioConfig) -> ScenarioResult:
+        """Execute a scenario and return results."""
+        ...
+
+
+@dataclass
+class RunnerProgress:
+    """Progress information for a scenario run batch.
+
+    Attributes:
+        total_scenarios: Total number of scenarios
+        completed: Number of completed scenarios
+        failed: Number of failed scenarios
+        running: Number of currently running scenarios
+        pending: Number of pending scenarios
+        start_time: When the batch started
+        estimated_remaining_seconds: Estimated time remaining
+    """
+    total_scenarios: int
+    completed: int = 0
+    failed: int = 0
+    running: int = 0
+    pending: int = 0
+    start_time: Optional[datetime] = None
+    estimated_remaining_seconds: Optional[float] = None
+
+    @property
+    def progress_percent(self) -> float:
+        """Calculate completion percentage."""
+        if self.total_scenarios == 0:
+            return 100.0
+        return (self.completed + self.failed) / self.total_scenarios * 100
+
+    @property
+    def is_complete(self) -> bool:
+        """Check if all scenarios are finished."""
+        return (self.completed + self.failed) >= self.total_scenarios
+
+
+ProgressCallback = Callable[[RunnerProgress], None]
+
+
+class ScenarioRunner:
+    """Runner for parallel portfolio simulations.
+
+    Executes multiple simulation scenarios in parallel using configurable
+    execution modes (sequential, threaded, or process-based).
+
+    Example:
+        >>> def simulate(config: ScenarioConfig) -> ScenarioResult:
+        ...     # Your simulation logic
+        ...     return ScenarioResult(
+        ...         scenario_id=config.scenario_id,
+        ...         scenario_name=config.name,
+        ...         status=ScenarioStatus.COMPLETED,
+        ...         start_time=datetime.now(),
+        ...     )
+        ...
+        >>> runner = ScenarioRunner(executor=simulate)
+        >>> scenarios = [
+        ...     ScenarioConfig(name="Bull Market", strategy_params={"leverage": 1.5}),
+        ...     ScenarioConfig(name="Bear Market", strategy_params={"leverage": 0.5}),
+        ... ]
+        >>> results = runner.run(scenarios)
+        >>> print(f"Completed: {len([r for r in results if r.is_successful])}")
+    """
+
+    def __init__(
+        self,
+        executor: ScenarioExecutor,
+        mode: ExecutionMode = ExecutionMode.THREADED,
+        max_workers: Optional[int] = None,
+        timeout_seconds: Optional[float] = None,
+    ):
+        """Initialize the scenario runner.
+
+        Args:
+            executor: Function that executes a single scenario
+            mode: Execution mode (sequential, threaded, process)
+            max_workers: Maximum number of parallel workers (None = auto)
+            timeout_seconds: Timeout per scenario (None = no timeout)
+        """
+        self.executor = executor
+        self.mode = mode
+        self.max_workers = max_workers
+        self.timeout_seconds = timeout_seconds
+        self._lock = threading.Lock()
+        self._cancelled = False
+        self._progress = RunnerProgress(total_scenarios=0)
+        self._progress_callbacks: List[ProgressCallback] = []
+
+    def add_progress_callback(self, callback: ProgressCallback) -> None:
+        """Add a callback for progress updates.
+
+        Args:
+            callback: Function to call with progress updates
+        """
+        with self._lock:
+            self._progress_callbacks.append(callback)
+
+    def remove_progress_callback(self, callback: ProgressCallback) -> None:
+        """Remove a progress callback.
+
+        Args:
+            callback: Callback to remove
+        """
+        with self._lock:
+            if callback in self._progress_callbacks:
+                self._progress_callbacks.remove(callback)
+
+    def _notify_progress(self) -> None:
+        """Notify all registered progress callbacks."""
+        with self._lock:
+            callbacks = self._progress_callbacks.copy()
+            progress = copy.copy(self._progress)
+
+        for callback in callbacks:
+            try:
+                callback(progress)
+            except Exception:
+                pass  # Don't let callback errors affect execution
+
+    def _update_progress(
+        self,
+        completed_delta: int = 0,
+        failed_delta: int = 0,
+        running_delta: int = 0,
+        pending_delta: int = 0,
+    ) -> None:
+        """Update progress counters thread-safely."""
+        with self._lock:
+            self._progress.completed += completed_delta
+            self._progress.failed += failed_delta
+            self._progress.running += running_delta
+            self._progress.pending += pending_delta
+
+            # Estimate remaining time
+            if self._progress.start_time and self._progress.completed > 0:
+                elapsed = (datetime.now() - self._progress.start_time).total_seconds()
+                avg_time = elapsed / self._progress.completed
+                remaining = self._progress.pending + self._progress.running
+                self._progress.estimated_remaining_seconds = avg_time * remaining
+
+        self._notify_progress()
+
+    def _execute_scenario(self, config: ScenarioConfig) -> ScenarioResult:
+        """Execute a single scenario with error handling.
+
+        Args:
+            config: Scenario configuration
+
+        Returns:
+            ScenarioResult with outcome
+        """
+        start_time = datetime.now()
+
+        # Check if cancelled
+        if self._cancelled:
+            return ScenarioResult(
+                scenario_id=config.scenario_id,
+                scenario_name=config.name,
+                status=ScenarioStatus.CANCELLED,
+                start_time=start_time,
+                end_time=datetime.now(),
+            )
+
+        self._update_progress(running_delta=1, pending_delta=-1)
+
+        try:
+            result = self.executor(config)
+            result.end_time = datetime.now()
+            result.duration_seconds = (result.end_time - start_time).total_seconds()
+
+            if result.status == ScenarioStatus.COMPLETED:
+                self._update_progress(completed_delta=1, running_delta=-1)
+            else:
+                self._update_progress(failed_delta=1, running_delta=-1)
+
+            return result
+
+        except Exception as e:
+            end_time = datetime.now()
+            self._update_progress(failed_delta=1, running_delta=-1)
+            return ScenarioResult(
+                scenario_id=config.scenario_id,
+                scenario_name=config.name,
+                status=ScenarioStatus.FAILED,
+                start_time=start_time,
+                end_time=end_time,
+                duration_seconds=(end_time - start_time).total_seconds(),
+                error_message=str(e),
+            )
+
+    def run(
+        self,
+        scenarios: List[ScenarioConfig],
+        progress_callback: Optional[ProgressCallback] = None,
+    ) -> List[ScenarioResult]:
+        """Run multiple scenarios.
+
+        Args:
+            scenarios: List of scenario configurations to run
+            progress_callback: Optional callback for progress updates
+
+        Returns:
+            List of results in the same order as input scenarios
+        """
+        if not scenarios:
+            return []
+
+        # Reset state
+        self._cancelled = False
+        self._progress = RunnerProgress(
+            total_scenarios=len(scenarios),
+            pending=len(scenarios),
+            start_time=datetime.now(),
+        )
+
+        if progress_callback:
+            self.add_progress_callback(progress_callback)
+
+        try:
+            if self.mode == ExecutionMode.SEQUENTIAL:
+                results = self._run_sequential(scenarios)
+            elif self.mode == ExecutionMode.THREADED:
+                results = self._run_parallel(scenarios, ThreadPoolExecutor)
+            elif self.mode == ExecutionMode.PROCESS:
+                results = self._run_parallel(scenarios, ProcessPoolExecutor)
+            else:
+                raise ValueError(f"Unknown execution mode: {self.mode}")
+
+            return results
+
+        finally:
+            if progress_callback:
+                self.remove_progress_callback(progress_callback)
+
+    def _run_sequential(
+        self, scenarios: List[ScenarioConfig]
+    ) -> List[ScenarioResult]:
+        """Run scenarios sequentially.
+
+        Args:
+            scenarios: List of scenarios to run
+
+        Returns:
+            List of results in order
+        """
+        results = []
+        for config in scenarios:
+            if self._cancelled:
+                results.append(ScenarioResult(
+                    scenario_id=config.scenario_id,
+                    scenario_name=config.name,
+                    status=ScenarioStatus.CANCELLED,
+                    start_time=datetime.now(),
+                ))
+            else:
+                results.append(self._execute_scenario(config))
+        return results
+
+    def _run_parallel(
+        self,
+        scenarios: List[ScenarioConfig],
+        executor_class: type,
+    ) -> List[ScenarioResult]:
+        """Run scenarios in parallel using a pool executor.
+
+        Args:
+            scenarios: List of scenarios to run
+            executor_class: ThreadPoolExecutor or ProcessPoolExecutor
+
+        Returns:
+            List of results in original order
+        """
+        # Map scenario IDs to their original indices
+        id_to_index = {config.scenario_id: i for i, config in enumerate(scenarios)}
+        results = [None] * len(scenarios)
+
+        with executor_class(max_workers=self.max_workers) as pool:
+            # Submit all scenarios
+            future_to_id = {
+                pool.submit(self._execute_scenario, config): config.scenario_id
+                for config in scenarios
+            }
+
+            # Collect results as they complete
+            for future in as_completed(future_to_id, timeout=self.timeout_seconds):
+                scenario_id = future_to_id[future]
+                index = id_to_index[scenario_id]
+
+                try:
+                    result = future.result()
+                    results[index] = result
+                except Exception as e:
+                    # Create error result for this scenario
+                    config = scenarios[index]
+                    results[index] = ScenarioResult(
+                        scenario_id=config.scenario_id,
+                        scenario_name=config.name,
+                        status=ScenarioStatus.FAILED,
+                        start_time=datetime.now(),
+                        error_message=str(e),
+                    )
+
+        return results
+
+    def cancel(self) -> None:
+        """Cancel all pending scenarios.
+
+        Running scenarios will complete, but pending ones will be skipped.
+        """
+        with self._lock:
+            self._cancelled = True
+
+    def get_progress(self) -> RunnerProgress:
+        """Get current progress information.
+
+        Returns:
+            Current progress state
+        """
+        with self._lock:
+            return copy.copy(self._progress)
+
+
+class ScenarioBatchBuilder:
+    """Builder for creating batches of scenario configurations.
+
+    Provides convenient methods for generating variations of scenarios
+    for sensitivity analysis, parameter sweeps, etc.
+
+    Example:
+        >>> builder = ScenarioBatchBuilder()
+        >>> scenarios = (
+        ...     builder
+        ...     .with_base_config(symbols=["AAPL", "GOOGL"])
+        ...     .vary_parameter("leverage", [0.5, 1.0, 1.5, 2.0])
+        ...     .vary_date_range(
+        ...         date(2020, 1, 1),
+        ...         date(2023, 12, 31),
+        ...         window_months=12,
+        ...     )
+        ...     .build()
+        ... )
+    """
+
+    def __init__(self):
+        """Initialize the batch builder."""
+        self._base_config: Dict[str, Any] = {}
+        self._parameter_variations: Dict[str, List[Any]] = {}
+        self._date_ranges: List[Tuple[date, date]] = []
+
+    def with_base_config(self, **kwargs) -> "ScenarioBatchBuilder":
+        """Set base configuration for all scenarios.
+
+        Args:
+            **kwargs: Configuration parameters
+
+        Returns:
+            Self for chaining
+        """
+        self._base_config.update(kwargs)
+        return self
+
+    def vary_parameter(
+        self, name: str, values: List[Any]
+    ) -> "ScenarioBatchBuilder":
+        """Add a parameter to vary across scenarios.
+
+        Args:
+            name: Parameter name (in strategy_params or risk_params)
+            values: List of values to use
+
+        Returns:
+            Self for chaining
+        """
+        self._parameter_variations[name] = values
+        return self
+
+    def vary_date_range(
+        self,
+        start: date,
+        end: date,
+        window_months: int = 12,
+        step_months: int = 3,
+    ) -> "ScenarioBatchBuilder":
+        """Add rolling date windows.
+
+        Args:
+            start: Overall start date
+            end: Overall end date
+            window_months: Size of each window in months
+            step_months: Step between windows in months
+
+        Returns:
+            Self for chaining
+        """
+        from datetime import timedelta
+        from dateutil.relativedelta import relativedelta
+
+        current_start = start
+        while current_start < end:
+            current_end = current_start + relativedelta(months=window_months)
+            if current_end > end:
+                current_end = end
+            self._date_ranges.append((current_start, current_end))
+            current_start += relativedelta(months=step_months)
+
+        return self
+
+    def with_date_ranges(
+        self, ranges: List[Tuple[date, date]]
+    ) -> "ScenarioBatchBuilder":
+        """Set explicit date ranges.
+
+        Args:
+            ranges: List of (start_date, end_date) tuples
+
+        Returns:
+            Self for chaining
+        """
+        self._date_ranges.extend(ranges)
+        return self
+
+    def build(self) -> List[ScenarioConfig]:
+        """Build all scenario configurations.
+
+        Creates the Cartesian product of all variations.
+
+        Returns:
+            List of ScenarioConfig objects
+        """
+        import itertools
+
+        scenarios = []
+
+        # Get all parameter combinations
+        param_names = list(self._parameter_variations.keys())
+        param_values = [self._parameter_variations[name] for name in param_names]
+
+        if param_values:
+            param_combinations = list(itertools.product(*param_values))
+        else:
+            param_combinations = [()]
+
+        # Get date ranges (use single None tuple if no ranges)
+        date_ranges = self._date_ranges if self._date_ranges else [(None, None)]
+
+        # Generate all combinations
+        for param_combo in param_combinations:
+            for start_date, end_date in date_ranges:
+                # Build scenario config
+                config_dict = copy.deepcopy(self._base_config)
+
+                # Set dates
+                if start_date is not None:
+                    config_dict["start_date"] = start_date
+                if end_date is not None:
+                    config_dict["end_date"] = end_date
+
+                # Set parameter variations
+                strategy_params = config_dict.get("strategy_params", {})
+                for name, value in zip(param_names, param_combo):
+                    strategy_params[name] = value
+                config_dict["strategy_params"] = strategy_params
+
+                # Generate descriptive name
+                name_parts = []
+                for name, value in zip(param_names, param_combo):
+                    name_parts.append(f"{name}={value}")
+                if start_date:
+                    name_parts.append(f"{start_date.year}")
+
+                if name_parts:
+                    config_dict["name"] = " | ".join(name_parts)
+
+                scenarios.append(ScenarioConfig(**config_dict))
+
+        return scenarios
+
+    def clear(self) -> "ScenarioBatchBuilder":
+        """Clear all configuration.
+
+        Returns:
+            Self for chaining
+        """
+        self._base_config = {}
+        self._parameter_variations = {}
+        self._date_ranges = []
+        return self
+
+
+def aggregate_results(results: List[ScenarioResult]) -> Dict[str, Any]:
+    """Aggregate results from multiple scenarios.
+
+    Args:
+        results: List of scenario results
+
+    Returns:
+        Dictionary with aggregated statistics
+    """
+    if not results:
+        return {
+            "total_scenarios": 0,
+            "successful": 0,
+            "failed": 0,
+        }
+
+    successful = [r for r in results if r.is_successful]
+    failed = [r for r in results if r.status == ScenarioStatus.FAILED]
+
+    # Calculate aggregate metrics
+    returns = [float(r.total_return) for r in successful if r.total_return]
+    drawdowns = [float(r.max_drawdown) for r in successful if r.max_drawdown]
+    durations = [r.duration_seconds for r in results if r.duration_seconds]
+
+    aggregate = {
+        "total_scenarios": len(results),
+        "successful": len(successful),
+        "failed": len(failed),
+        "success_rate": len(successful) / len(results) if results else 0,
+        "total_duration_seconds": sum(durations),
+        "avg_duration_seconds": sum(durations) / len(durations) if durations else 0,
+    }
+
+    if returns:
+        aggregate.update({
+            "avg_return": sum(returns) / len(returns),
+            "min_return": min(returns),
+            "max_return": max(returns),
+            "median_return": sorted(returns)[len(returns) // 2],
+        })
+
+    if drawdowns:
+        aggregate.update({
+            "avg_max_drawdown": sum(drawdowns) / len(drawdowns),
+            "worst_drawdown": min(drawdowns),  # More negative is worse
+        })
+
+    # Best and worst scenarios
+    if successful:
+        best = max(successful, key=lambda r: float(r.total_return or 0))
+        worst = min(successful, key=lambda r: float(r.total_return or 0))
+        aggregate["best_scenario"] = {
+            "name": best.scenario_name,
+            "return": str(best.total_return),
+        }
+        aggregate["worst_scenario"] = {
+            "name": worst.scenario_name,
+            "return": str(worst.total_return),
+        }
+
+    return aggregate