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Bollinger Bands SMA 20-2 Strategy

This strategy uses Bollinger Bands built from a 20-period simple moving average with a 2 standard deviation multiplier. It goes long when price crosses above the lower band and goes short when price crosses below the upper band. Positions reverse on opposite signals without explicit stop-losses.

Details

  • Entry Criteria:
    • Long: Close crosses above lower band.
    • Short: Close crosses below upper band.
  • Long/Short: Both directions.
  • Exit Criteria:
    • Opposite signal.
  • Stops: None.
  • Default Values:
    • Bollinger Length = 20
    • Bollinger Multiplier = 2
  • Filters:
    • Category: Mean Reversion
    • Direction: Both
    • Indicators: Single
    • Stops: No
    • Complexity: Basic
    • Timeframe: Intraday
    • Seasonality: No
    • Neural networks: No
    • Divergence: No
    • Risk level: Low
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>
/// BollingerBandsSma202Strategy using EMA crossover for trend timing.
/// Enters long on golden cross, short on death cross.
/// </summary>
public class BollingerBandsSma202Strategy : 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 BollingerBandsSma202Strategy()
	{
		_fastEmaPeriod = Param(nameof(FastEmaPeriod), 130)
			.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;
	}
}