This code snippet demonstrates how to implement a trailing stop strategy for cumulative positions in trading using the ProBuilder language. A trailing stop is a type of stop-loss order that moves with the market price and is designed to protect gains by enabling a trade to remain open and continue to profit as long as the price is moving in the investor’s favor. The code specifically handles the complexity of adjusting the stop-loss level when additional positions are cumulated.

//*********************************************************************************
// https://www.prorealcode.com/blog/trading/complete-trailing-stop-code-function/
//
// trailing stop function
//-------------------------------------------------------------
//reset the stoploss value
IF NOT ONMARKET THEN
    NewSL = 0
    MyPositionPrice = 0
ENDIF
//-------------------------------------------------------------
// Update locked in profit, if any, after comulating positions
PositionCount = abs(CountOfPosition)
IF NewSL > 0 THEN
    IF PositionCount > PositionCount[1] THEN
        IF LongOnMarket THEN
            NewSL = max(NewSL,PositionPrice * NewSL / MyPositionPrice)
        ELSE
            NewSL = min(NewSL,PositionPrice * NewSL / MyPositionPrice)
        ENDIF
    ENDIF
ENDIF
//-------------------------------------------------------------
trailingstart = 20 //trailing will start @trailinstart points profit
trailingstep = 5 //trailing step to move the "stoploss"
//manage long positions
IF LONGONMARKET THEN
    //first move (breakeven)
    IF newSL=0 AND close-PositionPrice>=trailingstart*pipsize THEN
        newSL = PositionPrice+trailingstep*pipsize
    ENDIF
    //next moves
    IF newSL>0 AND close-newSL>=trailingstep*pipsize THEN
        newSL = newSL+trailingstep*pipsize
    ENDIF
ENDIF
//manage short positions
IF SHORTONMARKET THEN
    //first move (breakeven)
    IF newSL=0 AND PositionPrice-close>=trailingstart*pipsize THEN
        newSL = PositionPrice-trailingstep*pipsize
    ENDIF
    //next moves
    IF newSL>0 AND newSL-close>=trailingstep*pipsize THEN
        newSL = newSL-trailingstep*pipsize
    ENDIF
ENDIF
//stop order to exit the positions
IF newSL>0 THEN
    SELL AT newSL STOP
    EXITSHORT AT newSL STOP
ENDIF
MyPositionPrice = PositionPrice
//*********************************************************************************

Explanation of the Code:

• Reset Stop-Loss: At the beginning, if the trader is not in the market, the stop-loss (NewSL) and the position price (MyPositionPrice) are reset to zero.
• Update Stop-Loss for Cumulative Positions: If new positions are added (detected by an increase in the absolute count of positions), the stop-loss is adjusted based on whether the market is long or short. For long positions, it sets the stop-loss to the higher of the current stop-loss or the adjusted position price. For short positions, it sets it to the lower.
• Trailing Stop Parameters: Defines the points at which the trailing stop starts (trailingstart) and the step size for the stop movement (trailingstep).
• Manage Long and Short Positions: Adjusts the stop-loss for both long and short positions as the market price moves favorably, ensuring the stop-loss is moved in steps defined by trailingstep, starting after a profit defined by trailingstart.
• Execute Stop Orders: If the stop-loss is greater than zero, the positions are exited at the stop-loss price, effectively locking in profits and limiting losses.

This code is a practical example of how to manage and adjust trailing stops dynamically in a trading environment, particularly useful for strategies involving cumulative positions.