diff --git a/backtest_service.py b/backtest_service.py
new file mode 100644
index 0000000..d0f7609
--- /dev/null
+++ b/backtest_service.py
@@ -0,0 +1,372 @@
+"""Backtesting engine using pure pandas/numpy - no external backtesting libraries."""
+
+import logging
+from typing import Any
+
+import numpy as np
+import pandas as pd
+
+from obb_utils import fetch_historical
+
+logger = logging.getLogger(__name__)
+
+_EQUITY_CURVE_MAX_POINTS = 20
+_MIN_BARS_FOR_SINGLE_POINT = 2
+
+
+# ---------------------------------------------------------------------------
+# Internal signal computation helpers
+# ---------------------------------------------------------------------------
+
+
+def _extract_closes(result: Any) -> pd.Series:
+    """Pull close prices from an OBBject result into a float Series."""
+    bars = result.results
+    closes = [getattr(bar, "close", None) for bar in bars]
+    return pd.Series(closes, dtype=float).dropna().reset_index(drop=True)
+
+
+def _compute_sma_signals(
+    prices: pd.Series, short_window: int, long_window: int
+) -> pd.Series:
+    """Return position series (1=long, 0=flat) from SMA crossover strategy.
+
+    Buy when short SMA crosses above long SMA; sell when it crosses below.
+    """
+    short_ma = prices.rolling(short_window).mean()
+    long_ma = prices.rolling(long_window).mean()
+
+    # 1 where short > long, else 0; NaN before long_window filled with 0
+    signal = (short_ma > long_ma).astype(int)
+    signal.iloc[: long_window - 1] = 0
+    return signal
+
+
+def _compute_rsi(prices: pd.Series, period: int) -> pd.Series:
+    """Compute Wilder RSI for a price series."""
+    delta = prices.diff()
+    gain = delta.clip(lower=0)
+    loss = (-delta).clip(lower=0)
+
+    avg_gain = gain.ewm(alpha=1 / period, adjust=False).mean()
+    avg_loss = loss.ewm(alpha=1 / period, adjust=False).mean()
+
+    # When avg_loss == 0 and avg_gain > 0, RSI = 100; avoid division by zero.
+    rsi = pd.Series(np.where(
+        avg_loss == 0,
+        np.where(avg_gain == 0, 50.0, 100.0),
+        100 - (100 / (1 + avg_gain / avg_loss)),
+    ), index=prices.index, dtype=float)
+    # Preserve NaN for the initial diff period
+    rsi[avg_gain.isna()] = np.nan
+    return rsi
+
+
+def _compute_rsi_signals(
+    prices: pd.Series, period: int, oversold: float, overbought: float
+) -> pd.Series:
+    """Return position series (1=long, 0=flat) from RSI strategy.
+
+    Buy when RSI < oversold; sell when RSI > overbought.
+    """
+    rsi = _compute_rsi(prices, period)
+    position = pd.Series(0, index=prices.index, dtype=int)
+    in_trade = False
+
+    for i in range(len(prices)):
+        rsi_val = rsi.iloc[i]
+        if pd.isna(rsi_val):
+            continue
+        if not in_trade and rsi_val < oversold:
+            in_trade = True
+        elif in_trade and rsi_val > overbought:
+            in_trade = False
+        if in_trade:
+            position.iloc[i] = 1
+
+    return position
+
+
+# ---------------------------------------------------------------------------
+# Shared metrics computation
+# ---------------------------------------------------------------------------
+
+
+def _compute_metrics(equity: pd.Series, trades: int) -> dict[str, Any]:
+    """Compute standard backtest performance metrics from an equity curve.
+
+    Parameters
+    ----------
+    equity:
+        Daily portfolio value series starting from initial_capital.
+    trades:
+        Number of completed round-trip trades.
+
+    Returns
+    -------
+    dict with keys: total_return, annualized_return, sharpe_ratio,
+    max_drawdown, win_rate, total_trades, equity_curve.
+    """
+    n = len(equity)
+    initial = float(equity.iloc[0])
+    final = float(equity.iloc[-1])
+
+    total_return = (final - initial) / initial if initial != 0 else 0.0
+
+    trading_days = max(n - 1, 1)
+    annualized_return = (1 + total_return) ** (252 / trading_days) - 1
+
+    # Sharpe ratio (annualized, risk-free rate = 0)
+    sharpe_ratio: float | None = None
+    if n > 1:
+        daily_returns = equity.pct_change().dropna()
+        std = float(daily_returns.std())
+        if std > 0:
+            sharpe_ratio = float(daily_returns.mean() / std * np.sqrt(252))
+
+    # Maximum drawdown
+    rolling_max = equity.cummax()
+    drawdown = (equity - rolling_max) / rolling_max
+    max_drawdown = float(drawdown.min())
+
+    # Win rate: undefined when no trades
+    win_rate: float | None = None
+    if trades > 0:
+        # Approximate: compare each trade entry/exit pair captured in equity
+        win_rate = None  # will be overridden by callers that track trades
+
+    # Equity curve - last N points as plain Python floats
+    last_n = equity.iloc[-_EQUITY_CURVE_MAX_POINTS:]
+    equity_curve = [round(float(v), 4) for v in last_n]
+
+    return {
+        "total_return": round(total_return, 6),
+        "annualized_return": round(annualized_return, 6),
+        "sharpe_ratio": round(sharpe_ratio, 6) if sharpe_ratio is not None else None,
+        "max_drawdown": round(max_drawdown, 6),
+        "win_rate": win_rate,
+        "total_trades": trades,
+        "equity_curve": equity_curve,
+    }
+
+
+def _simulate_positions(
+    prices: pd.Series,
+    positions: pd.Series,
+    initial_capital: float,
+) -> tuple[pd.Series, int, int]:
+    """Simulate portfolio equity given a position series and prices.
+
+    Returns (equity_curve, total_trades, winning_trades).
+    A trade is a complete buy->sell round-trip.
+    """
+    # Daily returns when in position
+    price_returns = prices.pct_change().fillna(0.0)
+    strategy_returns = positions.shift(1).fillna(0).astype(float) * price_returns
+
+    equity = initial_capital * (1 + strategy_returns).cumprod()
+    equity.iloc[0] = initial_capital
+
+    # Count round trips
+    trade_changes = positions.diff().abs()
+    entries = int((trade_changes == 1).sum())
+    exits = int((trade_changes == -1).sum())
+    total_trades = min(entries, exits)  # only completed round trips
+
+    # Count wins: each completed trade where exit value > entry value
+    winning_trades = 0
+    in_trade = False
+    entry_price = 0.0
+    for i in range(len(positions)):
+        pos = int(positions.iloc[i])
+        price = float(prices.iloc[i])
+        if not in_trade and pos == 1:
+            in_trade = True
+            entry_price = price
+        elif in_trade and pos == 0:
+            in_trade = False
+            if price > entry_price:
+                winning_trades += 1
+
+    return equity, total_trades, winning_trades
+
+
+# ---------------------------------------------------------------------------
+# Public strategy functions
+# ---------------------------------------------------------------------------
+
+
+async def backtest_sma_crossover(
+    symbol: str,
+    short_window: int,
+    long_window: int,
+    days: int,
+    initial_capital: float,
+) -> dict[str, Any]:
+    """Run SMA crossover backtest for a single symbol."""
+    hist = await fetch_historical(symbol, days)
+    if hist is None:
+        raise ValueError(f"No historical data available for {symbol}")
+
+    prices = _extract_closes(hist)
+    if len(prices) <= long_window:
+        raise ValueError(
+            f"Insufficient data: need >{long_window} bars, got {len(prices)}"
+        )
+
+    positions = _compute_sma_signals(prices, short_window, long_window)
+    equity, total_trades, winning_trades = _simulate_positions(
+        prices, positions, initial_capital
+    )
+
+    result = _compute_metrics(equity, total_trades)
+    if total_trades > 0:
+        result["win_rate"] = round(winning_trades / total_trades, 6)
+    return result
+
+
+async def backtest_rsi(
+    symbol: str,
+    period: int,
+    oversold: float,
+    overbought: float,
+    days: int,
+    initial_capital: float,
+) -> dict[str, Any]:
+    """Run RSI-based backtest for a single symbol."""
+    hist = await fetch_historical(symbol, days)
+    if hist is None:
+        raise ValueError(f"No historical data available for {symbol}")
+
+    prices = _extract_closes(hist)
+    if len(prices) <= period:
+        raise ValueError(
+            f"Insufficient data: need >{period} bars, got {len(prices)}"
+        )
+
+    positions = _compute_rsi_signals(prices, period, oversold, overbought)
+    equity, total_trades, winning_trades = _simulate_positions(
+        prices, positions, initial_capital
+    )
+
+    result = _compute_metrics(equity, total_trades)
+    if total_trades > 0:
+        result["win_rate"] = round(winning_trades / total_trades, 6)
+    return result
+
+
+async def backtest_buy_and_hold(
+    symbol: str,
+    days: int,
+    initial_capital: float,
+) -> dict[str, Any]:
+    """Run a simple buy-and-hold backtest as a benchmark."""
+    hist = await fetch_historical(symbol, days)
+    if hist is None:
+        raise ValueError(f"No historical data available for {symbol}")
+
+    prices = _extract_closes(hist)
+    if len(prices) < _MIN_BARS_FOR_SINGLE_POINT:
+        raise ValueError(
+            f"Insufficient data: need at least 2 bars, got {len(prices)}"
+        )
+
+    # Always fully invested - position is 1 from day 0
+    positions = pd.Series(1, index=prices.index, dtype=int)
+    equity, _, _ = _simulate_positions(prices, positions, initial_capital)
+
+    result = _compute_metrics(equity, trades=1)
+    # Buy-and-hold: 1 trade, win_rate is whether final > initial
+    result["win_rate"] = 1.0 if result["total_return"] > 0 else 0.0
+    result["total_trades"] = 1
+    return result
+
+
+async def backtest_momentum(
+    symbols: list[str],
+    lookback: int,
+    top_n: int,
+    rebalance_days: int,
+    days: int,
+    initial_capital: float,
+) -> dict[str, Any]:
+    """Run momentum strategy: every rebalance_days pick top_n symbols by lookback return."""
+    # Fetch all price series
+    price_map: dict[str, pd.Series] = {}
+    for sym in symbols:
+        hist = await fetch_historical(sym, days)
+        if hist is not None:
+            closes = _extract_closes(hist)
+            if len(closes) > lookback:
+                price_map[sym] = closes
+
+    if not price_map:
+        raise ValueError("No price data available for any of the requested symbols")
+
+    # Align all price series to the same length (min across symbols)
+    min_len = min(len(v) for v in price_map.values())
+    aligned = {sym: s.iloc[:min_len].reset_index(drop=True) for sym, s in price_map.items()}
+
+    n_bars = min_len
+    portfolio_value = initial_capital
+    equity_values: list[float] = [initial_capital]
+    allocation_history: list[dict[str, Any]] = []
+    total_trades = 0
+
+    current_symbols: list[str] = []
+    current_weights: list[float] = []
+    entry_prices: dict[str, float] = {}
+    winning_trades = 0
+
+    for bar in range(1, n_bars):
+        # Rebalance check
+        if bar % rebalance_days == 0 and bar >= lookback:
+            # Rank symbols by lookback-period return
+            returns: dict[str, float] = {}
+            for sym, prices in aligned.items():
+                if bar >= lookback:
+                    ret = (prices.iloc[bar] / prices.iloc[bar - lookback]) - 1
+                    returns[sym] = ret
+
+            sorted_syms = sorted(returns, key=returns.get, reverse=True)  # type: ignore[arg-type]
+            selected = sorted_syms[:top_n]
+            weight = 1.0 / len(selected) if selected else 0.0
+
+            # Count closed positions as trades
+            for sym in current_symbols:
+                if sym in aligned:
+                    exit_price = float(aligned[sym].iloc[bar])
+                    entry_price = entry_prices.get(sym, exit_price)
+                    total_trades += 1
+                    if exit_price > entry_price:
+                        winning_trades += 1
+
+            current_symbols = selected
+            current_weights = [weight] * len(selected)
+            entry_prices = {sym: float(aligned[sym].iloc[bar]) for sym in selected}
+
+            allocation_history.append({
+                "bar": bar,
+                "symbols": selected,
+                "weights": current_weights,
+            })
+
+        # Compute portfolio daily return
+        if current_symbols:
+            daily_ret = 0.0
+            for sym, w in zip(current_symbols, current_weights):
+                prev_bar = bar - 1
+                prev_price = float(aligned[sym].iloc[prev_bar])
+                curr_price = float(aligned[sym].iloc[bar])
+                if prev_price != 0:
+                    daily_ret += w * (curr_price / prev_price - 1)
+            portfolio_value = portfolio_value * (1 + daily_ret)
+
+        equity_values.append(portfolio_value)
+
+    equity = pd.Series(equity_values, dtype=float)
+    result = _compute_metrics(equity, total_trades)
+    if total_trades > 0:
+        result["win_rate"] = round(winning_trades / total_trades, 6)
+    result["allocation_history"] = allocation_history
+    return result
diff --git a/main.py b/main.py
index 69961c0..296ddc4 100644
--- a/main.py
+++ b/main.py
@@ -38,6 +38,7 @@ from routes_shorts import router as shorts_router  # noqa: E402
 from routes_surveys import router as surveys_router  # noqa: E402
 from routes_technical import router as technical_router  # noqa: E402
 from routes_portfolio import router as portfolio_router  # noqa: E402
+from routes_backtest import router as backtest_router  # noqa: E402
 
 logging.basicConfig(
     level=settings.log_level.upper(),
@@ -83,6 +84,7 @@ app.include_router(economy_router)
 app.include_router(surveys_router)
 app.include_router(regulators_router)
 app.include_router(portfolio_router)
+app.include_router(backtest_router)
 
 
 @app.get("/health", response_model=dict[str, str])
diff --git a/routes_backtest.py b/routes_backtest.py
new file mode 100644
index 0000000..6b0e7df
--- /dev/null
+++ b/routes_backtest.py
@@ -0,0 +1,141 @@
+"""Routes for backtesting strategies."""
+
+import logging
+
+from fastapi import APIRouter, HTTPException
+from pydantic import BaseModel, Field
+
+import backtest_service
+from models import ApiResponse
+
+logger = logging.getLogger(__name__)
+
+router = APIRouter(prefix="/api/v1/backtest", tags=["backtest"])
+
+
+# ---------------------------------------------------------------------------
+# Request models
+# ---------------------------------------------------------------------------
+
+
+class BacktestRequest(BaseModel):
+    symbol: str = Field(..., min_length=1, max_length=20)
+    days: int = Field(default=365, ge=30, le=3650)
+    initial_capital: float = Field(default=10000.0, gt=0, le=1_000_000_000)
+
+
+class SMARequest(BacktestRequest):
+    short_window: int = Field(default=20, ge=5, le=100)
+    long_window: int = Field(default=50, ge=10, le=400)
+
+
+class RSIRequest(BacktestRequest):
+    period: int = Field(default=14, ge=2, le=50)
+    oversold: float = Field(default=30.0, ge=1, le=49)
+    overbought: float = Field(default=70.0, ge=51, le=99)
+
+
+class BuyAndHoldRequest(BacktestRequest):
+    pass
+
+
+class MomentumRequest(BaseModel):
+    symbols: list[str] = Field(..., min_length=2, max_length=20)
+    lookback: int = Field(default=60, ge=5, le=252)
+    top_n: int = Field(default=2, ge=1)
+    rebalance_days: int = Field(default=30, ge=5, le=252)
+    days: int = Field(default=365, ge=60, le=3650)
+    initial_capital: float = Field(default=10000.0, gt=0)
+
+
+# ---------------------------------------------------------------------------
+# Route handlers
+# ---------------------------------------------------------------------------
+
+
+@router.post("/sma-crossover", response_model=ApiResponse)
+async def sma_crossover(req: SMARequest) -> ApiResponse:
+    """SMA crossover strategy: buy when short SMA crosses above long SMA."""
+    try:
+        result = await backtest_service.backtest_sma_crossover(
+            req.symbol,
+            short_window=req.short_window,
+            long_window=req.long_window,
+            days=req.days,
+            initial_capital=req.initial_capital,
+        )
+        return ApiResponse(data=result)
+    except ValueError as exc:
+        logger.warning("SMA crossover backtest validation error: %s", exc)
+        raise HTTPException(status_code=400, detail=str(exc)) from exc
+    except Exception as exc:
+        logger.exception("SMA crossover backtest failed")
+        raise HTTPException(
+            status_code=502, detail="Data provider error. Check server logs."
+        ) from exc
+
+
+@router.post("/rsi", response_model=ApiResponse)
+async def rsi_strategy(req: RSIRequest) -> ApiResponse:
+    """RSI strategy: buy when RSI < oversold, sell when RSI > overbought."""
+    try:
+        result = await backtest_service.backtest_rsi(
+            req.symbol,
+            period=req.period,
+            oversold=req.oversold,
+            overbought=req.overbought,
+            days=req.days,
+            initial_capital=req.initial_capital,
+        )
+        return ApiResponse(data=result)
+    except ValueError as exc:
+        logger.warning("RSI backtest validation error: %s", exc)
+        raise HTTPException(status_code=400, detail=str(exc)) from exc
+    except Exception as exc:
+        logger.exception("RSI backtest failed")
+        raise HTTPException(
+            status_code=502, detail="Data provider error. Check server logs."
+        ) from exc
+
+
+@router.post("/buy-and-hold", response_model=ApiResponse)
+async def buy_and_hold(req: BuyAndHoldRequest) -> ApiResponse:
+    """Buy-and-hold benchmark: buy on day 1, hold through end of period."""
+    try:
+        result = await backtest_service.backtest_buy_and_hold(
+            req.symbol,
+            days=req.days,
+            initial_capital=req.initial_capital,
+        )
+        return ApiResponse(data=result)
+    except ValueError as exc:
+        logger.warning("Buy-and-hold backtest validation error: %s", exc)
+        raise HTTPException(status_code=400, detail=str(exc)) from exc
+    except Exception as exc:
+        logger.exception("Buy-and-hold backtest failed")
+        raise HTTPException(
+            status_code=502, detail="Data provider error. Check server logs."
+        ) from exc
+
+
+@router.post("/momentum", response_model=ApiResponse)
+async def momentum_strategy(req: MomentumRequest) -> ApiResponse:
+    """Momentum strategy: every rebalance_days pick top_n symbols by lookback return."""
+    try:
+        result = await backtest_service.backtest_momentum(
+            symbols=req.symbols,
+            lookback=req.lookback,
+            top_n=req.top_n,
+            rebalance_days=req.rebalance_days,
+            days=req.days,
+            initial_capital=req.initial_capital,
+        )
+        return ApiResponse(data=result)
+    except ValueError as exc:
+        logger.warning("Momentum backtest validation error: %s", exc)
+        raise HTTPException(status_code=400, detail=str(exc)) from exc
+    except Exception as exc:
+        logger.exception("Momentum backtest failed")
+        raise HTTPException(
+            status_code=502, detail="Data provider error. Check server logs."
+        ) from exc
diff --git a/tests/test_backtest_service.py b/tests/test_backtest_service.py
new file mode 100644
index 0000000..211eab4
--- /dev/null
+++ b/tests/test_backtest_service.py
@@ -0,0 +1,627 @@
+"""Unit tests for backtest_service - written FIRST (TDD RED phase)."""
+
+import numpy as np
+import pandas as pd
+import pytest
+
+import backtest_service
+
+
+# ---------------------------------------------------------------------------
+# Helpers
+# ---------------------------------------------------------------------------
+
+
+def _make_equity(values: list[float]) -> pd.Series:
+    """Build a simple equity-curve Series from a list of values."""
+    return pd.Series(values, dtype=float)
+
+
+def _rising_prices(n: int = 100, start: float = 100.0, step: float = 1.0) -> pd.Series:
+    """Linearly rising price series."""
+    return pd.Series([start + i * step for i in range(n)], dtype=float)
+
+
+def _flat_prices(n: int = 100, price: float = 100.0) -> pd.Series:
+    """Flat price series - no movement."""
+    return pd.Series([price] * n, dtype=float)
+
+
+def _oscillating_prices(n: int = 200, period: int = 40) -> pd.Series:
+    """Sinusoidal price series to generate crossover signals."""
+    t = np.arange(n)
+    prices = 100 + 20 * np.sin(2 * np.pi * t / period)
+    return pd.Series(prices, dtype=float)
+
+
+# ---------------------------------------------------------------------------
+# _compute_metrics tests
+# ---------------------------------------------------------------------------
+
+
+class TestComputeMetrics:
+    def test_total_return_positive(self):
+        equity = _make_equity([10000, 11000, 12000])
+        result = backtest_service._compute_metrics(equity, trades=1)
+        assert result["total_return"] == pytest.approx(0.2, abs=1e-6)
+
+    def test_total_return_negative(self):
+        equity = _make_equity([10000, 9000, 8000])
+        result = backtest_service._compute_metrics(equity, trades=1)
+        assert result["total_return"] == pytest.approx(-0.2, abs=1e-6)
+
+    def test_total_return_zero_on_flat(self):
+        equity = _make_equity([10000, 10000, 10000])
+        result = backtest_service._compute_metrics(equity, trades=0)
+        assert result["total_return"] == pytest.approx(0.0, abs=1e-6)
+
+    def test_annualized_return_shape(self):
+        # 252 daily bars => 1 trading year; 10000 -> 11000 = +10% annualized
+        values = [10000 * (1.0 + 0.1 / 252) ** i for i in range(253)]
+        equity = _make_equity(values)
+        result = backtest_service._compute_metrics(equity, trades=5)
+        # Should be close to 10% annualized
+        assert result["annualized_return"] == pytest.approx(0.1, abs=0.01)
+
+    def test_sharpe_ratio_positive_drift(self):
+        # Steadily rising equity with small daily increments -> positive Sharpe
+        values = [10000 + i * 10 for i in range(252)]
+        equity = _make_equity(values)
+        result = backtest_service._compute_metrics(equity, trades=5)
+        assert result["sharpe_ratio"] > 0
+
+    def test_sharpe_ratio_none_on_single_point(self):
+        equity = _make_equity([10000])
+        result = backtest_service._compute_metrics(equity, trades=0)
+        assert result["sharpe_ratio"] is None
+
+    def test_sharpe_ratio_none_on_zero_std(self):
+        # Perfectly flat equity => std = 0, Sharpe undefined
+        equity = _make_equity([10000] * 50)
+        result = backtest_service._compute_metrics(equity, trades=0)
+        assert result["sharpe_ratio"] is None
+
+    def test_max_drawdown_known_value(self):
+        # Peak 12000, trough 8000 => drawdown = (8000-12000)/12000 = -1/3
+        equity = _make_equity([10000, 12000, 8000, 9000])
+        result = backtest_service._compute_metrics(equity, trades=2)
+        assert result["max_drawdown"] == pytest.approx(-1 / 3, abs=1e-6)
+
+    def test_max_drawdown_zero_on_monotone_rise(self):
+        equity = _make_equity([10000, 11000, 12000, 13000])
+        result = backtest_service._compute_metrics(equity, trades=1)
+        assert result["max_drawdown"] == pytest.approx(0.0, abs=1e-6)
+
+    def test_total_trades_propagated(self):
+        equity = _make_equity([10000, 11000])
+        result = backtest_service._compute_metrics(equity, trades=7)
+        assert result["total_trades"] == 7
+
+    def test_win_rate_zero_trades(self):
+        equity = _make_equity([10000, 10000])
+        result = backtest_service._compute_metrics(equity, trades=0)
+        assert result["win_rate"] is None
+
+    def test_equity_curve_last_20_points(self):
+        values = list(range(100, 160))  # 60 points
+        equity = _make_equity(values)
+        result = backtest_service._compute_metrics(equity, trades=10)
+        assert len(result["equity_curve"]) == 20
+        assert result["equity_curve"][-1] == pytest.approx(159.0, abs=1e-6)
+
+    def test_equity_curve_shorter_than_20(self):
+        values = [10000, 11000, 12000]
+        equity = _make_equity(values)
+        result = backtest_service._compute_metrics(equity, trades=1)
+        assert len(result["equity_curve"]) == 3
+
+    def test_result_keys_present(self):
+        equity = _make_equity([10000, 11000])
+        result = backtest_service._compute_metrics(equity, trades=1)
+        expected_keys = {
+            "total_return",
+            "annualized_return",
+            "sharpe_ratio",
+            "max_drawdown",
+            "win_rate",
+            "total_trades",
+            "equity_curve",
+        }
+        assert expected_keys.issubset(result.keys())
+
+
+# ---------------------------------------------------------------------------
+# _compute_sma_signals tests
+# ---------------------------------------------------------------------------
+
+
+class TestComputeSmaSignals:
+    def test_returns_series_with_position_column(self):
+        prices = _oscillating_prices(200, period=40)
+        positions = backtest_service._compute_sma_signals(prices, short_window=5, long_window=20)
+        assert isinstance(positions, pd.Series)
+        assert len(positions) == len(prices)
+
+    def test_positions_are_zero_or_one(self):
+        prices = _oscillating_prices(200, period=40)
+        positions = backtest_service._compute_sma_signals(prices, short_window=5, long_window=20)
+        unique_vals = set(positions.dropna().unique())
+        assert unique_vals.issubset({0, 1})
+
+    def test_no_position_before_long_window(self):
+        prices = _oscillating_prices(200, period=40)
+        positions = backtest_service._compute_sma_signals(prices, short_window=5, long_window=20)
+        # Before long_window-1 data points, positions should be 0
+        assert (positions.iloc[: 19] == 0).all()
+
+    def test_generates_at_least_one_signal_on_oscillating(self):
+        prices = _oscillating_prices(300, period=60)
+        positions = backtest_service._compute_sma_signals(prices, short_window=5, long_window=20)
+        # Should flip between 0 and 1 at least once on oscillating data
+        changes = positions.diff().abs().sum()
+        assert changes > 0
+
+    def test_flat_prices_produce_no_signals(self):
+        prices = _flat_prices(100)
+        positions = backtest_service._compute_sma_signals(prices, short_window=5, long_window=20)
+        # After warm-up both SMAs equal price; short never strictly above long
+        assert (positions == 0).all()
+
+
+# ---------------------------------------------------------------------------
+# _compute_rsi tests
+# ---------------------------------------------------------------------------
+
+
+class TestComputeRsi:
+    def test_rsi_length(self):
+        prices = _rising_prices(50)
+        rsi = backtest_service._compute_rsi(prices, period=14)
+        assert len(rsi) == len(prices)
+
+    def test_rsi_range(self):
+        prices = _oscillating_prices(100, period=20)
+        rsi = backtest_service._compute_rsi(prices, period=14)
+        valid = rsi.dropna()
+        assert (valid >= 0).all()
+        assert (valid <= 100).all()
+
+    def test_rsi_rising_prices_high(self):
+        # Monotonically rising prices => RSI should be high (>= 70)
+        prices = _rising_prices(80, step=1.0)
+        rsi = backtest_service._compute_rsi(prices, period=14)
+        # After warm-up period, RSI should be very high
+        assert rsi.iloc[-1] >= 70
+
+    def test_rsi_falling_prices_low(self):
+        # Monotonically falling prices => RSI should be low (<= 30)
+        prices = pd.Series([100 - i * 0.8 for i in range(80)], dtype=float)
+        rsi = backtest_service._compute_rsi(prices, period=14)
+        assert rsi.iloc[-1] <= 30
+
+
+# ---------------------------------------------------------------------------
+# _compute_rsi_signals tests
+# ---------------------------------------------------------------------------
+
+
+class TestComputeRsiSignals:
+    def test_returns_series(self):
+        prices = _oscillating_prices(200, period=40)
+        positions = backtest_service._compute_rsi_signals(
+            prices, period=14, oversold=30, overbought=70
+        )
+        assert isinstance(positions, pd.Series)
+        assert len(positions) == len(prices)
+
+    def test_positions_are_zero_or_one(self):
+        prices = _oscillating_prices(200, period=40)
+        positions = backtest_service._compute_rsi_signals(
+            prices, period=14, oversold=30, overbought=70
+        )
+        unique_vals = set(positions.dropna().unique())
+        assert unique_vals.issubset({0, 1})
+
+
+# ---------------------------------------------------------------------------
+# backtest_sma_crossover tests (async integration of service layer)
+# ---------------------------------------------------------------------------
+
+
+class TestBacktestSmaCrossover:
+    @pytest.fixture
+    def mock_hist(self, monkeypatch):
+        """Patch fetch_historical to return a synthetic OBBject-like result."""
+        prices = _oscillating_prices(300, period=60).tolist()
+
+        class FakeBar:
+            def __init__(self, close):
+                self.close = close
+
+        class FakeResult:
+            results = [FakeBar(p) for p in prices]
+
+        async def fake_fetch(symbol, days, **kwargs):
+            return FakeResult()
+
+        monkeypatch.setattr(backtest_service, "fetch_historical", fake_fetch)
+        return FakeResult()
+
+    @pytest.mark.asyncio
+    async def test_returns_all_required_keys(self, mock_hist):
+        result = await backtest_service.backtest_sma_crossover(
+            "AAPL", short_window=5, long_window=20, days=365, initial_capital=10000
+        )
+        required = {
+            "total_return",
+            "annualized_return",
+            "sharpe_ratio",
+            "max_drawdown",
+            "win_rate",
+            "total_trades",
+            "equity_curve",
+        }
+        assert required.issubset(result.keys())
+
+    @pytest.mark.asyncio
+    async def test_equity_curve_max_20_points(self, mock_hist):
+        result = await backtest_service.backtest_sma_crossover(
+            "AAPL", short_window=5, long_window=20, days=365, initial_capital=10000
+        )
+        assert len(result["equity_curve"]) <= 20
+
+    @pytest.mark.asyncio
+    async def test_raises_value_error_on_no_data(self, monkeypatch):
+        async def fake_fetch(symbol, days, **kwargs):
+            return None
+
+        monkeypatch.setattr(backtest_service, "fetch_historical", fake_fetch)
+        with pytest.raises(ValueError, match="No historical data"):
+            await backtest_service.backtest_sma_crossover(
+                "AAPL", short_window=5, long_window=20, days=365, initial_capital=10000
+            )
+
+    @pytest.mark.asyncio
+    async def test_initial_capital_reflected_in_equity(self, mock_hist):
+        result = await backtest_service.backtest_sma_crossover(
+            "AAPL", short_window=5, long_window=20, days=365, initial_capital=50000
+        )
+        # equity_curve values should be in range related to 50000 initial capital
+        assert result["equity_curve"][0] > 0
+
+
+# ---------------------------------------------------------------------------
+# backtest_rsi tests
+# ---------------------------------------------------------------------------
+
+
+class TestBacktestRsi:
+    @pytest.fixture
+    def mock_hist(self, monkeypatch):
+        prices = _oscillating_prices(300, period=60).tolist()
+
+        class FakeBar:
+            def __init__(self, close):
+                self.close = close
+
+        class FakeResult:
+            results = [FakeBar(p) for p in prices]
+
+        async def fake_fetch(symbol, days, **kwargs):
+            return FakeResult()
+
+        monkeypatch.setattr(backtest_service, "fetch_historical", fake_fetch)
+
+    @pytest.mark.asyncio
+    async def test_returns_all_required_keys(self, mock_hist):
+        result = await backtest_service.backtest_rsi(
+            "AAPL", period=14, oversold=30, overbought=70, days=365, initial_capital=10000
+        )
+        required = {
+            "total_return",
+            "annualized_return",
+            "sharpe_ratio",
+            "max_drawdown",
+            "win_rate",
+            "total_trades",
+            "equity_curve",
+        }
+        assert required.issubset(result.keys())
+
+    @pytest.mark.asyncio
+    async def test_equity_curve_max_20_points(self, mock_hist):
+        result = await backtest_service.backtest_rsi(
+            "AAPL", period=14, oversold=30, overbought=70, days=365, initial_capital=10000
+        )
+        assert len(result["equity_curve"]) <= 20
+
+    @pytest.mark.asyncio
+    async def test_raises_value_error_on_no_data(self, monkeypatch):
+        async def fake_fetch(symbol, days, **kwargs):
+            return None
+
+        monkeypatch.setattr(backtest_service, "fetch_historical", fake_fetch)
+        with pytest.raises(ValueError, match="No historical data"):
+            await backtest_service.backtest_rsi(
+                "AAPL", period=14, oversold=30, overbought=70, days=365, initial_capital=10000
+            )
+
+
+# ---------------------------------------------------------------------------
+# backtest_buy_and_hold tests
+# ---------------------------------------------------------------------------
+
+
+class TestBacktestBuyAndHold:
+    @pytest.fixture
+    def mock_hist_rising(self, monkeypatch):
+        prices = _rising_prices(252, start=100.0, step=1.0).tolist()
+
+        class FakeBar:
+            def __init__(self, close):
+                self.close = close
+
+        class FakeResult:
+            results = [FakeBar(p) for p in prices]
+
+        async def fake_fetch(symbol, days, **kwargs):
+            return FakeResult()
+
+        monkeypatch.setattr(backtest_service, "fetch_historical", fake_fetch)
+
+    @pytest.mark.asyncio
+    async def test_returns_all_required_keys(self, mock_hist_rising):
+        result = await backtest_service.backtest_buy_and_hold(
+            "AAPL", days=365, initial_capital=10000
+        )
+        required = {
+            "total_return",
+            "annualized_return",
+            "sharpe_ratio",
+            "max_drawdown",
+            "win_rate",
+            "total_trades",
+            "equity_curve",
+        }
+        assert required.issubset(result.keys())
+
+    @pytest.mark.asyncio
+    async def test_total_trades_always_one(self, mock_hist_rising):
+        result = await backtest_service.backtest_buy_and_hold(
+            "AAPL", days=365, initial_capital=10000
+        )
+        assert result["total_trades"] == 1
+
+    @pytest.mark.asyncio
+    async def test_rising_prices_positive_return(self, mock_hist_rising):
+        result = await backtest_service.backtest_buy_and_hold(
+            "AAPL", days=365, initial_capital=10000
+        )
+        assert result["total_return"] > 0
+
+    @pytest.mark.asyncio
+    async def test_known_return_value(self, monkeypatch):
+        # 100 -> 200: 100% total return
+        prices = [100.0, 200.0]
+
+        class FakeBar:
+            def __init__(self, close):
+                self.close = close
+
+        class FakeResult:
+            results = [FakeBar(p) for p in prices]
+
+        async def fake_fetch(symbol, days, **kwargs):
+            return FakeResult()
+
+        monkeypatch.setattr(backtest_service, "fetch_historical", fake_fetch)
+        result = await backtest_service.backtest_buy_and_hold(
+            "AAPL", days=365, initial_capital=10000
+        )
+        assert result["total_return"] == pytest.approx(1.0, abs=1e-6)
+        assert result["equity_curve"][-1] == pytest.approx(20000.0, abs=1e-6)
+
+    @pytest.mark.asyncio
+    async def test_raises_value_error_on_no_data(self, monkeypatch):
+        async def fake_fetch(symbol, days, **kwargs):
+            return None
+
+        monkeypatch.setattr(backtest_service, "fetch_historical", fake_fetch)
+        with pytest.raises(ValueError, match="No historical data"):
+            await backtest_service.backtest_buy_and_hold("AAPL", days=365, initial_capital=10000)
+
+    @pytest.mark.asyncio
+    async def test_flat_prices_zero_return(self, monkeypatch):
+        prices = _flat_prices(50).tolist()
+
+        class FakeBar:
+            def __init__(self, close):
+                self.close = close
+
+        class FakeResult:
+            results = [FakeBar(p) for p in prices]
+
+        async def fake_fetch(symbol, days, **kwargs):
+            return FakeResult()
+
+        monkeypatch.setattr(backtest_service, "fetch_historical", fake_fetch)
+        result = await backtest_service.backtest_buy_and_hold(
+            "AAPL", days=365, initial_capital=10000
+        )
+        assert result["total_return"] == pytest.approx(0.0, abs=1e-6)
+
+
+# ---------------------------------------------------------------------------
+# backtest_momentum tests
+# ---------------------------------------------------------------------------
+
+
+class TestBacktestMomentum:
+    @pytest.fixture
+    def mock_multi_hist(self, monkeypatch):
+        """Three symbols with different return profiles."""
+        aapl_prices = _rising_prices(200, start=100.0, step=2.0).tolist()
+        msft_prices = _rising_prices(200, start=100.0, step=0.5).tolist()
+        googl_prices = _flat_prices(200, price=150.0).tolist()
+
+        price_map = {
+            "AAPL": aapl_prices,
+            "MSFT": msft_prices,
+            "GOOGL": googl_prices,
+        }
+
+        class FakeBar:
+            def __init__(self, close):
+                self.close = close
+
+        class FakeResult:
+            def __init__(self, prices):
+                self.results = [FakeBar(p) for p in prices]
+
+        async def fake_fetch(symbol, days, **kwargs):
+            return FakeResult(price_map[symbol])
+
+        monkeypatch.setattr(backtest_service, "fetch_historical", fake_fetch)
+
+    @pytest.mark.asyncio
+    async def test_returns_all_required_keys(self, mock_multi_hist):
+        result = await backtest_service.backtest_momentum(
+            symbols=["AAPL", "MSFT", "GOOGL"],
+            lookback=20,
+            top_n=2,
+            rebalance_days=30,
+            days=365,
+            initial_capital=10000,
+        )
+        required = {
+            "total_return",
+            "annualized_return",
+            "sharpe_ratio",
+            "max_drawdown",
+            "win_rate",
+            "total_trades",
+            "equity_curve",
+            "allocation_history",
+        }
+        assert required.issubset(result.keys())
+
+    @pytest.mark.asyncio
+    async def test_allocation_history_is_list(self, mock_multi_hist):
+        result = await backtest_service.backtest_momentum(
+            symbols=["AAPL", "MSFT", "GOOGL"],
+            lookback=20,
+            top_n=2,
+            rebalance_days=30,
+            days=365,
+            initial_capital=10000,
+        )
+        assert isinstance(result["allocation_history"], list)
+
+    @pytest.mark.asyncio
+    async def test_top_n_respected_in_allocations(self, mock_multi_hist):
+        result = await backtest_service.backtest_momentum(
+            symbols=["AAPL", "MSFT", "GOOGL"],
+            lookback=20,
+            top_n=2,
+            rebalance_days=30,
+            days=365,
+            initial_capital=10000,
+        )
+        for entry in result["allocation_history"]:
+            assert len(entry["symbols"]) <= 2
+
+    @pytest.mark.asyncio
+    async def test_raises_value_error_on_no_data(self, monkeypatch):
+        async def fake_fetch(symbol, days, **kwargs):
+            return None
+
+        monkeypatch.setattr(backtest_service, "fetch_historical", fake_fetch)
+        with pytest.raises(ValueError, match="No price data"):
+            await backtest_service.backtest_momentum(
+                symbols=["AAPL", "MSFT"],
+                lookback=20,
+                top_n=1,
+                rebalance_days=30,
+                days=365,
+                initial_capital=10000,
+            )
+
+    @pytest.mark.asyncio
+    async def test_equity_curve_max_20_points(self, mock_multi_hist):
+        result = await backtest_service.backtest_momentum(
+            symbols=["AAPL", "MSFT", "GOOGL"],
+            lookback=20,
+            top_n=2,
+            rebalance_days=30,
+            days=365,
+            initial_capital=10000,
+        )
+        assert len(result["equity_curve"]) <= 20
+
+
+# ---------------------------------------------------------------------------
+# Edge case: insufficient data
+# ---------------------------------------------------------------------------
+
+
+class TestEdgeCases:
+    @pytest.mark.asyncio
+    async def test_sma_crossover_insufficient_bars_raises(self, monkeypatch):
+        """Fewer bars than long_window should raise ValueError."""
+        prices = [100.0, 101.0, 102.0]  # Only 3 bars
+
+        class FakeBar:
+            def __init__(self, close):
+                self.close = close
+
+        class FakeResult:
+            results = [FakeBar(p) for p in prices]
+
+        async def fake_fetch(symbol, days, **kwargs):
+            return FakeResult()
+
+        monkeypatch.setattr(backtest_service, "fetch_historical", fake_fetch)
+        with pytest.raises(ValueError, match="Insufficient data"):
+            await backtest_service.backtest_sma_crossover(
+                "AAPL", short_window=5, long_window=20, days=365, initial_capital=10000
+            )
+
+    @pytest.mark.asyncio
+    async def test_rsi_insufficient_bars_raises(self, monkeypatch):
+        prices = [100.0, 101.0]
+
+        class FakeBar:
+            def __init__(self, close):
+                self.close = close
+
+        class FakeResult:
+            results = [FakeBar(p) for p in prices]
+
+        async def fake_fetch(symbol, days, **kwargs):
+            return FakeResult()
+
+        monkeypatch.setattr(backtest_service, "fetch_historical", fake_fetch)
+        with pytest.raises(ValueError, match="Insufficient data"):
+            await backtest_service.backtest_rsi(
+                "AAPL", period=14, oversold=30, overbought=70, days=365, initial_capital=10000
+            )
+
+    @pytest.mark.asyncio
+    async def test_buy_and_hold_single_bar_raises(self, monkeypatch):
+        prices = [100.0]
+
+        class FakeBar:
+            def __init__(self, close):
+                self.close = close
+
+        class FakeResult:
+            results = [FakeBar(p) for p in prices]
+
+        async def fake_fetch(symbol, days, **kwargs):
+            return FakeResult()
+
+        monkeypatch.setattr(backtest_service, "fetch_historical", fake_fetch)
+        with pytest.raises(ValueError, match="Insufficient data"):
+            await backtest_service.backtest_buy_and_hold(
+                "AAPL", days=365, initial_capital=10000
+            )
diff --git a/tests/test_routes_backtest.py b/tests/test_routes_backtest.py
new file mode 100644
index 0000000..36e1547
--- /dev/null
+++ b/tests/test_routes_backtest.py
@@ -0,0 +1,443 @@
+"""Integration tests for backtest routes - written FIRST (TDD RED phase)."""
+
+from unittest.mock import AsyncMock, patch
+
+import pytest
+from httpx import ASGITransport, AsyncClient
+
+from main import app
+
+
+@pytest.fixture
+async def client():
+    transport = ASGITransport(app=app)
+    async with AsyncClient(transport=transport, base_url="http://test") as c:
+        yield c
+
+
+# Shared mock response used across strategy tests
+MOCK_BACKTEST_RESULT = {
+    "total_return": 0.15,
+    "annualized_return": 0.14,
+    "sharpe_ratio": 1.2,
+    "max_drawdown": -0.08,
+    "win_rate": 0.6,
+    "total_trades": 10,
+    "equity_curve": [10000 + i * 75 for i in range(20)],
+}
+
+MOCK_MOMENTUM_RESULT = {
+    **MOCK_BACKTEST_RESULT,
+    "allocation_history": [
+        {"date": "2024-01-01", "symbols": ["AAPL", "MSFT"], "weights": [0.5, 0.5]},
+    ],
+}
+
+
+# ---------------------------------------------------------------------------
+# POST /api/v1/backtest/sma-crossover
+# ---------------------------------------------------------------------------
+
+
+@pytest.mark.asyncio
+@patch("routes_backtest.backtest_service.backtest_sma_crossover", new_callable=AsyncMock)
+async def test_sma_crossover_happy_path(mock_fn, client):
+    mock_fn.return_value = MOCK_BACKTEST_RESULT
+    resp = await client.post(
+        "/api/v1/backtest/sma-crossover",
+        json={
+            "symbol": "AAPL",
+            "short_window": 20,
+            "long_window": 50,
+            "days": 365,
+            "initial_capital": 10000,
+        },
+    )
+    assert resp.status_code == 200
+    data = resp.json()
+    assert data["success"] is True
+    assert data["data"]["total_return"] == pytest.approx(0.15)
+    assert data["data"]["total_trades"] == 10
+    assert len(data["data"]["equity_curve"]) == 20
+    mock_fn.assert_called_once_with(
+        "AAPL",
+        short_window=20,
+        long_window=50,
+        days=365,
+        initial_capital=10000.0,
+    )
+
+
+@pytest.mark.asyncio
+@patch("routes_backtest.backtest_service.backtest_sma_crossover", new_callable=AsyncMock)
+async def test_sma_crossover_default_values(mock_fn, client):
+    mock_fn.return_value = MOCK_BACKTEST_RESULT
+    resp = await client.post(
+        "/api/v1/backtest/sma-crossover",
+        json={"symbol": "MSFT"},
+    )
+    assert resp.status_code == 200
+    mock_fn.assert_called_once_with(
+        "MSFT",
+        short_window=20,
+        long_window=50,
+        days=365,
+        initial_capital=10000.0,
+    )
+
+
+@pytest.mark.asyncio
+async def test_sma_crossover_missing_symbol(client):
+    resp = await client.post(
+        "/api/v1/backtest/sma-crossover",
+        json={"short_window": 20, "long_window": 50},
+    )
+    assert resp.status_code == 422
+
+
+@pytest.mark.asyncio
+async def test_sma_crossover_short_window_too_small(client):
+    resp = await client.post(
+        "/api/v1/backtest/sma-crossover",
+        json={"symbol": "AAPL", "short_window": 2, "long_window": 50},
+    )
+    assert resp.status_code == 422
+
+
+@pytest.mark.asyncio
+async def test_sma_crossover_long_window_too_large(client):
+    resp = await client.post(
+        "/api/v1/backtest/sma-crossover",
+        json={"symbol": "AAPL", "short_window": 20, "long_window": 500},
+    )
+    assert resp.status_code == 422
+
+
+@pytest.mark.asyncio
+async def test_sma_crossover_days_too_few(client):
+    resp = await client.post(
+        "/api/v1/backtest/sma-crossover",
+        json={"symbol": "AAPL", "days": 5},
+    )
+    assert resp.status_code == 422
+
+
+@pytest.mark.asyncio
+async def test_sma_crossover_days_too_many(client):
+    resp = await client.post(
+        "/api/v1/backtest/sma-crossover",
+        json={"symbol": "AAPL", "days": 9999},
+    )
+    assert resp.status_code == 422
+
+
+@pytest.mark.asyncio
+async def test_sma_crossover_capital_zero(client):
+    resp = await client.post(
+        "/api/v1/backtest/sma-crossover",
+        json={"symbol": "AAPL", "initial_capital": 0},
+    )
+    assert resp.status_code == 422
+
+
+@pytest.mark.asyncio
+@patch("routes_backtest.backtest_service.backtest_sma_crossover", new_callable=AsyncMock)
+async def test_sma_crossover_service_error_returns_502(mock_fn, client):
+    mock_fn.side_effect = RuntimeError("Data fetch failed")
+    resp = await client.post(
+        "/api/v1/backtest/sma-crossover",
+        json={"symbol": "AAPL", "short_window": 20, "long_window": 50},
+    )
+    assert resp.status_code == 502
+
+
+@pytest.mark.asyncio
+@patch("routes_backtest.backtest_service.backtest_sma_crossover", new_callable=AsyncMock)
+async def test_sma_crossover_value_error_returns_400(mock_fn, client):
+    mock_fn.side_effect = ValueError("No historical data")
+    resp = await client.post(
+        "/api/v1/backtest/sma-crossover",
+        json={"symbol": "AAPL", "short_window": 20, "long_window": 50},
+    )
+    assert resp.status_code == 400
+
+
+# ---------------------------------------------------------------------------
+# POST /api/v1/backtest/rsi
+# ---------------------------------------------------------------------------
+
+
+@pytest.mark.asyncio
+@patch("routes_backtest.backtest_service.backtest_rsi", new_callable=AsyncMock)
+async def test_rsi_happy_path(mock_fn, client):
+    mock_fn.return_value = MOCK_BACKTEST_RESULT
+    resp = await client.post(
+        "/api/v1/backtest/rsi",
+        json={
+            "symbol": "AAPL",
+            "period": 14,
+            "oversold": 30,
+            "overbought": 70,
+            "days": 365,
+            "initial_capital": 10000,
+        },
+    )
+    assert resp.status_code == 200
+    data = resp.json()
+    assert data["success"] is True
+    assert data["data"]["sharpe_ratio"] == pytest.approx(1.2)
+    mock_fn.assert_called_once_with(
+        "AAPL",
+        period=14,
+        oversold=30.0,
+        overbought=70.0,
+        days=365,
+        initial_capital=10000.0,
+    )
+
+
+@pytest.mark.asyncio
+@patch("routes_backtest.backtest_service.backtest_rsi", new_callable=AsyncMock)
+async def test_rsi_default_values(mock_fn, client):
+    mock_fn.return_value = MOCK_BACKTEST_RESULT
+    resp = await client.post("/api/v1/backtest/rsi", json={"symbol": "AAPL"})
+    assert resp.status_code == 200
+    mock_fn.assert_called_once_with(
+        "AAPL",
+        period=14,
+        oversold=30.0,
+        overbought=70.0,
+        days=365,
+        initial_capital=10000.0,
+    )
+
+
+@pytest.mark.asyncio
+async def test_rsi_missing_symbol(client):
+    resp = await client.post("/api/v1/backtest/rsi", json={"period": 14})
+    assert resp.status_code == 422
+
+
+@pytest.mark.asyncio
+async def test_rsi_period_too_small(client):
+    resp = await client.post(
+        "/api/v1/backtest/rsi",
+        json={"symbol": "AAPL", "period": 1},
+    )
+    assert resp.status_code == 422
+
+
+@pytest.mark.asyncio
+async def test_rsi_oversold_too_high(client):
+    # oversold must be < 50
+    resp = await client.post(
+        "/api/v1/backtest/rsi",
+        json={"symbol": "AAPL", "oversold": 55, "overbought": 70},
+    )
+    assert resp.status_code == 422
+
+
+@pytest.mark.asyncio
+async def test_rsi_overbought_too_low(client):
+    # overbought must be > 50
+    resp = await client.post(
+        "/api/v1/backtest/rsi",
+        json={"symbol": "AAPL", "oversold": 30, "overbought": 45},
+    )
+    assert resp.status_code == 422
+
+
+@pytest.mark.asyncio
+@patch("routes_backtest.backtest_service.backtest_rsi", new_callable=AsyncMock)
+async def test_rsi_service_error_returns_502(mock_fn, client):
+    mock_fn.side_effect = RuntimeError("upstream error")
+    resp = await client.post("/api/v1/backtest/rsi", json={"symbol": "AAPL"})
+    assert resp.status_code == 502
+
+
+@pytest.mark.asyncio
+@patch("routes_backtest.backtest_service.backtest_rsi", new_callable=AsyncMock)
+async def test_rsi_value_error_returns_400(mock_fn, client):
+    mock_fn.side_effect = ValueError("Insufficient data")
+    resp = await client.post("/api/v1/backtest/rsi", json={"symbol": "AAPL"})
+    assert resp.status_code == 400
+
+
+# ---------------------------------------------------------------------------
+# POST /api/v1/backtest/buy-and-hold
+# ---------------------------------------------------------------------------
+
+
+@pytest.mark.asyncio
+@patch("routes_backtest.backtest_service.backtest_buy_and_hold", new_callable=AsyncMock)
+async def test_buy_and_hold_happy_path(mock_fn, client):
+    mock_fn.return_value = MOCK_BACKTEST_RESULT
+    resp = await client.post(
+        "/api/v1/backtest/buy-and-hold",
+        json={"symbol": "AAPL", "days": 365, "initial_capital": 10000},
+    )
+    assert resp.status_code == 200
+    data = resp.json()
+    assert data["success"] is True
+    assert data["data"]["total_return"] == pytest.approx(0.15)
+    mock_fn.assert_called_once_with("AAPL", days=365, initial_capital=10000.0)
+
+
+@pytest.mark.asyncio
+@patch("routes_backtest.backtest_service.backtest_buy_and_hold", new_callable=AsyncMock)
+async def test_buy_and_hold_default_values(mock_fn, client):
+    mock_fn.return_value = MOCK_BACKTEST_RESULT
+    resp = await client.post("/api/v1/backtest/buy-and-hold", json={"symbol": "AAPL"})
+    assert resp.status_code == 200
+    mock_fn.assert_called_once_with("AAPL", days=365, initial_capital=10000.0)
+
+
+@pytest.mark.asyncio
+async def test_buy_and_hold_missing_symbol(client):
+    resp = await client.post("/api/v1/backtest/buy-and-hold", json={"days": 365})
+    assert resp.status_code == 422
+
+
+@pytest.mark.asyncio
+async def test_buy_and_hold_days_too_few(client):
+    resp = await client.post(
+        "/api/v1/backtest/buy-and-hold",
+        json={"symbol": "AAPL", "days": 10},
+    )
+    assert resp.status_code == 422
+
+
+@pytest.mark.asyncio
+@patch("routes_backtest.backtest_service.backtest_buy_and_hold", new_callable=AsyncMock)
+async def test_buy_and_hold_service_error_returns_502(mock_fn, client):
+    mock_fn.side_effect = RuntimeError("provider down")
+    resp = await client.post("/api/v1/backtest/buy-and-hold", json={"symbol": "AAPL"})
+    assert resp.status_code == 502
+
+
+@pytest.mark.asyncio
+@patch("routes_backtest.backtest_service.backtest_buy_and_hold", new_callable=AsyncMock)
+async def test_buy_and_hold_value_error_returns_400(mock_fn, client):
+    mock_fn.side_effect = ValueError("No historical data")
+    resp = await client.post("/api/v1/backtest/buy-and-hold", json={"symbol": "AAPL"})
+    assert resp.status_code == 400
+
+
+# ---------------------------------------------------------------------------
+# POST /api/v1/backtest/momentum
+# ---------------------------------------------------------------------------
+
+
+@pytest.mark.asyncio
+@patch("routes_backtest.backtest_service.backtest_momentum", new_callable=AsyncMock)
+async def test_momentum_happy_path(mock_fn, client):
+    mock_fn.return_value = MOCK_MOMENTUM_RESULT
+    resp = await client.post(
+        "/api/v1/backtest/momentum",
+        json={
+            "symbols": ["AAPL", "MSFT", "GOOGL"],
+            "lookback": 60,
+            "top_n": 2,
+            "rebalance_days": 30,
+            "days": 365,
+            "initial_capital": 10000,
+        },
+    )
+    assert resp.status_code == 200
+    data = resp.json()
+    assert data["success"] is True
+    assert "allocation_history" in data["data"]
+    assert data["data"]["total_trades"] == 10
+    mock_fn.assert_called_once_with(
+        symbols=["AAPL", "MSFT", "GOOGL"],
+        lookback=60,
+        top_n=2,
+        rebalance_days=30,
+        days=365,
+        initial_capital=10000.0,
+    )
+
+
+@pytest.mark.asyncio
+@patch("routes_backtest.backtest_service.backtest_momentum", new_callable=AsyncMock)
+async def test_momentum_default_values(mock_fn, client):
+    mock_fn.return_value = MOCK_MOMENTUM_RESULT
+    resp = await client.post(
+        "/api/v1/backtest/momentum",
+        json={"symbols": ["AAPL", "MSFT"]},
+    )
+    assert resp.status_code == 200
+    mock_fn.assert_called_once_with(
+        symbols=["AAPL", "MSFT"],
+        lookback=60,
+        top_n=2,
+        rebalance_days=30,
+        days=365,
+        initial_capital=10000.0,
+    )
+
+
+@pytest.mark.asyncio
+async def test_momentum_missing_symbols(client):
+    resp = await client.post("/api/v1/backtest/momentum", json={"lookback": 60})
+    assert resp.status_code == 422
+
+
+@pytest.mark.asyncio
+async def test_momentum_too_few_symbols(client):
+    # min_length=2 on symbols list
+    resp = await client.post(
+        "/api/v1/backtest/momentum",
+        json={"symbols": ["AAPL"]},
+    )
+    assert resp.status_code == 422
+
+
+@pytest.mark.asyncio
+async def test_momentum_too_many_symbols(client):
+    symbols = [f"SYM{i}" for i in range(25)]
+    resp = await client.post(
+        "/api/v1/backtest/momentum",
+        json={"symbols": symbols},
+    )
+    assert resp.status_code == 422
+
+
+@pytest.mark.asyncio
+async def test_momentum_lookback_too_small(client):
+    resp = await client.post(
+        "/api/v1/backtest/momentum",
+        json={"symbols": ["AAPL", "MSFT"], "lookback": 2},
+    )
+    assert resp.status_code == 422
+
+
+@pytest.mark.asyncio
+async def test_momentum_days_too_few(client):
+    resp = await client.post(
+        "/api/v1/backtest/momentum",
+        json={"symbols": ["AAPL", "MSFT"], "days": 10},
+    )
+    assert resp.status_code == 422
+
+
+@pytest.mark.asyncio
+@patch("routes_backtest.backtest_service.backtest_momentum", new_callable=AsyncMock)
+async def test_momentum_service_error_returns_502(mock_fn, client):
+    mock_fn.side_effect = RuntimeError("provider down")
+    resp = await client.post(
+        "/api/v1/backtest/momentum",
+        json={"symbols": ["AAPL", "MSFT"]},
+    )
+    assert resp.status_code == 502
+
+
+@pytest.mark.asyncio
+@patch("routes_backtest.backtest_service.backtest_momentum", new_callable=AsyncMock)
+async def test_momentum_value_error_returns_400(mock_fn, client):
+    mock_fn.side_effect = ValueError("No price data available")
+    resp = await client.post(
+        "/api/v1/backtest/momentum",
+        json={"symbols": ["AAPL", "MSFT"]},
+    )
+    assert resp.status_code == 400