Bollinger Bands Lower Band Reversion

Bollinger Bands Lower Band Reversion Strategy (Pure Entry) STRATEGY DESCRIPTION: Fires a BUY signal when price crosses ABOVE the lower Bollinger Band, signaling a potential mean-reversion bounce after the stock traded at/below the lower band on the prior candle. CORE LOGIC (Step by Step): STEP 1: Calculate Bollinger Bands (20-period, 2 std-dev) basis (middle band) = 20-period SMA of Close dev = 20-period stdev of Close (population stdev, ddof=0, matching TradingView's ta.stdev) x 2.0 lower_band = basis - dev upper_band = basis + dev STEP 2: Check Crossover Condition previous_close <= previous_lower_band (was at/below the band) AND current_close > current_lower_band (now back above it) IF both true: → LOWER BAND CROSSOVER DETECTED! STEP 3: Volume Filter IF current_volume < min_volume (default 25,000): Signal rejected (avoids dead/illiquid stocks) STEP 4: Signal Generation Generate a BUY signal (once per symbol per day) tagged BOLLINGER_LOWER_REVERSION, with basis/lower_band/upper_band values attached. PARAMETERS: - length: int, default 20 -> Bollinger Band lookback period - mult: float, default 2.0 -> standard-deviation multiplier for the bands - min_volume: int, default 25000 -> minimum current-candle volume to accept a signal NOTE ON SCOPE: This is a pure entry screener - no stop-loss, target, or exit management is simulated, consistent with how every other strategy in this system works. WHY THIS MATTERS: - The lower Bollinger Band acts as a dynamic, volatility-adjusted support level - A close crossing back above the lower band after touching/breaching it often marks the start of a short-term mean-reversion bounce - The volume filter avoids signals on thinly-traded, low-liquidity names