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Bollinger Band Width Breakout

Bollinger Band Width measures the spread between the upper and lower bands. Expanding width suggests volatility and possible trend formation. This strategy trades breakouts when the width is increasing.

Testing indicates an average annual return of about 151%. It performs best in the stocks market.

Price position relative to the middle band sets direction. A widening channel with price above the mid-band triggers longs, while a widening channel below it triggers shorts.

Exits occur when the band width contracts or a volatility stop is reached.

Details

  • Entry Criteria: Band width expanding and price relative to middle band.
  • Long/Short: Both directions.
  • Exit Criteria: Band width contracts or stop.
  • Stops: Yes.
  • Default Values:
    • BollingerPeriod = 20
    • BollingerDeviation = 2.0m
    • AtrMultiplier = 2.0m
    • CandleType = TimeSpan.FromMinutes(5)
  • Filters:
    • Category: Breakout
    • Direction: Both
    • Indicators: Bollinger Bands, ATR
    • Stops: Yes
    • Complexity: Basic
    • Timeframe: Intraday
    • 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>
/// Strategy that trades on Bollinger Bands Width expansion.
/// It identifies periods of increasing volatility (widening Bollinger Bands)
/// and trades in the direction of the trend as identified by price position relative to the middle band.
/// </summary>
public class BollingerBandWidthStrategy : Strategy
{
	private readonly StrategyParam<int> _bollingerPeriod;
	private readonly StrategyParam<decimal> _bollingerDeviation;
	private readonly StrategyParam<DataType> _candleType;
	private readonly StrategyParam<int> _cooldownBars;

	private decimal _prevWidth;
	private int _cooldown;

	/// <summary>
	/// Period for Bollinger Bands calculation.
	/// </summary>
	public int BollingerPeriod
	{
		get => _bollingerPeriod.Value;
		set => _bollingerPeriod.Value = value;
	}

	/// <summary>
	/// Deviation for Bollinger Bands calculation.
	/// </summary>
	public decimal BollingerDeviation
	{
		get => _bollingerDeviation.Value;
		set => _bollingerDeviation.Value = value;
	}

	/// <summary>
	/// Type of candles used for strategy calculation.
	/// </summary>
	public DataType CandleType
	{
		get => _candleType.Value;
		set => _candleType.Value = value;
	}

	/// <summary>
	/// Cooldown bars between trades.
	/// </summary>
	public int CooldownBars
	{
		get => _cooldownBars.Value;
		set => _cooldownBars.Value = value;
	}

	/// <summary>
	/// Initialize the Bollinger Band Width strategy.
	/// </summary>
	public BollingerBandWidthStrategy()
	{
		_bollingerPeriod = Param(nameof(BollingerPeriod), 20)
			.SetDisplay("Bollinger Period", "Period for Bollinger Bands calculation", "Indicators")
			.SetOptimize(10, 30, 5);

		_bollingerDeviation = Param(nameof(BollingerDeviation), 2.0m)
			.SetDisplay("Bollinger Deviation", "Deviation for Bollinger Bands calculation", "Indicators")
			.SetOptimize(1.5m, 2.5m, 0.25m);

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

		_cooldownBars = Param(nameof(CooldownBars), 500)
			.SetRange(1, 1000)
			.SetDisplay("Cooldown Bars", "Bars to wait between trades", "General");
	}

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

	/// <inheritdoc />
	protected override void OnReseted()
	{
		base.OnReseted();
		_prevWidth = default;
		_cooldown = default;
	}

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

		_prevWidth = 0;
		_cooldown = 0;

		var bollinger = new BollingerBands
		{
			Length = BollingerPeriod,
			Width = BollingerDeviation
		};

		var subscription = SubscribeCandles(CandleType);
		subscription
			.BindEx(bollinger, ProcessCandle)
			.Start();

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

	private void ProcessCandle(ICandleMessage candle, IIndicatorValue bollingerValue)
	{
		if (candle.State != CandleStates.Finished)
			return;

		if (!bollingerValue.IsFormed)
			return;

		var bb = (BollingerBandsValue)bollingerValue;

		if (bb.UpBand is not decimal upperBand ||
			bb.LowBand is not decimal lowerBand ||
			bb.MovingAverage is not decimal middleBand)
			return;

		var bbWidth = upperBand - lowerBand;

		if (_prevWidth == 0)
		{
			_prevWidth = bbWidth;
			return;
		}

		if (_cooldown > 0)
		{
			_cooldown--;
			_prevWidth = bbWidth;
			return;
		}

		var isBBWidthExpanding = bbWidth > _prevWidth;

		if (Position == 0 && isBBWidthExpanding)
		{
			if (candle.ClosePrice > middleBand)
			{
				BuyMarket();
				_cooldown = CooldownBars;
			}
			else
			{
				SellMarket();
				_cooldown = CooldownBars;
			}
		}
		else if (Position > 0 && !isBBWidthExpanding)
		{
			SellMarket();
			_cooldown = CooldownBars;
		}
		else if (Position < 0 && !isBBWidthExpanding)
		{
			BuyMarket();
			_cooldown = CooldownBars;
		}

		_prevWidth = bbWidth;
	}
}