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diff --git a/tests/edge_cases/test_empty_data.py b/tests/edge_cases/test_empty_data.py
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+++ b/tests/edge_cases/test_empty_data.py
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+"""Tests for empty/zero data edge cases."""
+
+import sys
+from datetime import datetime, timezone, timedelta
+from decimal import Decimal
+from pathlib import Path
+
+sys.path.insert(0, str(Path(__file__).resolve().parents[2] / "services" / "strategy-engine"))
+sys.path.insert(0, str(Path(__file__).resolve().parents[2] / "services" / "backtester" / "src"))
+sys.path.insert(0, str(Path(__file__).resolve().parents[2] / "services" / "order-executor" / "src"))
+sys.path.insert(0, str(Path(__file__).resolve().parents[2] / "services" / "portfolio-manager" / "src"))
+
+from shared.models import Candle, Signal, OrderSide, Position
+from backtester.engine import BacktestEngine
+from backtester.metrics import TradeRecord, compute_detailed_metrics
+from portfolio_manager.portfolio import PortfolioTracker
+from order_executor.risk_manager import RiskManager
+from strategies.rsi_strategy import RsiStrategy
+
+
+class TestBacktestEngineEmptyCandles:
+    """BacktestEngine.run([]) should return valid result with 0 trades."""
+
+    def test_run_empty_candles(self):
+        strategy = RsiStrategy()
+        engine = BacktestEngine(strategy, initial_balance=Decimal("10000"))
+        result = engine.run([])
+        assert result.total_trades == 0
+        assert result.initial_balance == Decimal("10000")
+        assert result.final_balance == Decimal("10000")
+        assert result.profit == Decimal("0")
+        assert result.symbol == ""
+
+
+class TestPortfolioTrackerEmpty:
+    """PortfolioTracker.get_all_positions() on fresh tracker returns empty list."""
+
+    def test_fresh_tracker_returns_empty(self):
+        tracker = PortfolioTracker()
+        positions = tracker.get_all_positions()
+        assert positions == []
+
+    def test_get_position_returns_none_for_unknown_symbol(self):
+        tracker = PortfolioTracker()
+        assert tracker.get_position("BTCUSDT") is None
+
+
+class TestRiskManagerZeroBalance:
+    """RiskManager.check with zero balance should reject BUY signals."""
+
+    def test_zero_balance_rejects_buy(self):
+        rm = RiskManager(
+            max_position_size=Decimal("0.5"),
+            stop_loss_pct=Decimal("5"),
+            daily_loss_limit_pct=Decimal("3"),
+        )
+        signal = Signal(
+            strategy="test",
+            symbol="BTCUSDT",
+            side=OrderSide.BUY,
+            price=Decimal("50000"),
+            quantity=Decimal("0.01"),
+            reason="test buy",
+        )
+        result = rm.check(
+            signal=signal,
+            balance=Decimal("0"),
+            positions={},
+            daily_pnl=Decimal("0"),
+        )
+        assert result.allowed is False
+
+    def test_zero_balance_allows_sell(self):
+        rm = RiskManager(
+            max_position_size=Decimal("0.5"),
+            stop_loss_pct=Decimal("5"),
+            daily_loss_limit_pct=Decimal("3"),
+        )
+        signal = Signal(
+            strategy="test",
+            symbol="BTCUSDT",
+            side=OrderSide.SELL,
+            price=Decimal("50000"),
+            quantity=Decimal("0.01"),
+            reason="test sell",
+        )
+        result = rm.check(
+            signal=signal,
+            balance=Decimal("0"),
+            positions={},
+            daily_pnl=Decimal("0"),
+        )
+        # SELL doesn't require balance, so should be allowed
+        assert result.allowed is True
+
+
+class TestComputeDetailedMetricsEmpty:
+    """compute_detailed_metrics with empty trades returns zeroed metrics."""
+
+    def test_empty_trades(self):
+        metrics = compute_detailed_metrics(
+            trades=[],
+            initial_balance=Decimal("10000"),
+            final_balance=Decimal("10000"),
+        )
+        assert metrics.total_return == 0.0
+        assert metrics.total_trades == 0
+        assert metrics.winning_trades == 0
+        assert metrics.losing_trades == 0
+        assert metrics.win_rate == 0.0
+        assert metrics.sharpe_ratio == 0.0
+        assert metrics.max_drawdown == 0.0
+        assert metrics.max_drawdown_duration == timedelta(0)