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Bollinger Bands Strategy

Strategy trading Bollinger Bands breakouts. Buys when the price closes above the upper band and sells when it closes below the lower band. Exits on a simple moving average cross or when a stop loss is hit.

Details

  • Entry Criteria:
    • Long: close above upper Bollinger Band
    • Short: close below lower Bollinger Band
  • Long/Short: Both
  • Exit Criteria:
    • Long: close below SMA or price hits stop loss
    • Short: close above SMA or price hits stop loss
  • Stops: Percent from entry price
  • Default Values:
    • BbLength = 120
    • BbDeviation = 2m
    • SmaLength = 110
    • StopLossPercent = 6m
    • CandleType = TimeSpan.FromMinutes(5).TimeFrame()
  • Filters:
    • Category: Breakout
    • Direction: Both
    • Indicators: Bollinger Bands, SMA
    • Stops: Yes
    • Complexity: Basic
    • Timeframe: Mid-term
    • Seasonality: No
    • Neural Networks: No
    • Divergence: No
    • Risk Level: Medium
using System;
using System.Collections.Generic;

using Ecng.Common;

using StockSharp.Algo.Indicators;
using StockSharp.Algo.Strategies;
using StockSharp.BusinessEntities;
using StockSharp.Messages;

namespace StockSharp.Samples.Strategies;

/// <summary>
/// BollingerBandsStrategy using EMA crossover for trend timing.
/// Enters long on golden cross, short on death cross.
/// </summary>
public class BollingerBandsStrategy : Strategy
{
	private readonly StrategyParam<int> _fastEmaPeriod;
	private readonly StrategyParam<int> _slowEmaPeriod;
	private readonly StrategyParam<DataType> _candleType;

	private decimal _prevFastEma;
	private decimal _prevSlowEma;

	public int FastEmaPeriod { get => _fastEmaPeriod.Value; set => _fastEmaPeriod.Value = value; }
	public int SlowEmaPeriod { get => _slowEmaPeriod.Value; set => _slowEmaPeriod.Value = value; }
	public DataType CandleType { get => _candleType.Value; set => _candleType.Value = value; }

	public BollingerBandsStrategy()
	{
		_fastEmaPeriod = Param(nameof(FastEmaPeriod), 120)
			.SetGreaterThanZero()
			.SetDisplay("Fast EMA", "Fast EMA period", "Indicators");

		_slowEmaPeriod = Param(nameof(SlowEmaPeriod), 450)
			.SetGreaterThanZero()
			.SetDisplay("Slow EMA", "Slow EMA period", "Indicators");

		_candleType = Param(nameof(CandleType), TimeSpan.FromMinutes(1).TimeFrame())
			.SetDisplay("Candle Type", "Type of candles to use", "General");
	}

	/// <inheritdoc />
	public override IEnumerable<(Security sec, DataType dt)> GetWorkingSecurities()
	{
		return [(Security, CandleType)];
	}

	/// <inheritdoc />
	protected override void OnReseted()
	{
		base.OnReseted();
		_prevFastEma = 0m;
		_prevSlowEma = 0m;
	}

	/// <inheritdoc />
	protected override void OnStarted2(DateTime time)
	{
		base.OnStarted2(time);

		var fastEma = new ExponentialMovingAverage { Length = FastEmaPeriod };
		var slowEma = new ExponentialMovingAverage { Length = SlowEmaPeriod };

		var subscription = SubscribeCandles(CandleType);
		subscription
			.Bind(fastEma, slowEma, ProcessCandle)
			.Start();

		var area = CreateChartArea();
		if (area != null)
		{
			DrawCandles(area, subscription);
			DrawIndicator(area, fastEma);
			DrawIndicator(area, slowEma);
			DrawOwnTrades(area);
		}
	}

	private void ProcessCandle(ICandleMessage candle, decimal fastEmaValue, decimal slowEmaValue)
	{
		if (candle.State != CandleStates.Finished)
			return;

		if (_prevFastEma == 0m || _prevSlowEma == 0m)
		{
			_prevFastEma = fastEmaValue;
			_prevSlowEma = slowEmaValue;
			return;
		}

		if (_prevFastEma <= _prevSlowEma && fastEmaValue > slowEmaValue && Position <= 0)
		{
			BuyMarket();
		}
		else if (_prevFastEma >= _prevSlowEma && fastEmaValue < slowEmaValue && Position >= 0)
		{
			SellMarket();
		}

		_prevFastEma = fastEmaValue;
		_prevSlowEma = slowEmaValue;
	}
}