Positive slippage exists, but is it actually passed back?
Posted: Sat Oct 31, 2026 7:38 am
Every broker brochure says slippage works both ways. In practice, plenty of retail setups handle the two directions differently. Some pass price improvement through to the client in full. Some pass it back only up to a small cap, then fill at the requested price. Some never pass it at all and keep the difference.
The way to find out is boring and cheap: place a few dozen market orders on a liquid pair during active hours, small size, and record clicked price against fill price. Do the same for both buys and sells. Count how many fills are better than clicked, how many are worse, and how large each side is.
A healthy result looks roughly symmetric, with the average slippage near zero and occasional improvements as large as the occasional deterioration. A result where 15 percent of fills are worse by around 0.3 pips and nothing is ever better is telling you something, even though no single fill looks suspicious.
Also check order type. Limit orders typically fill at the limit or better, while market orders carry the slippage in both directions, and stop orders mostly carry it one way. Mixing them in one sample muddies the answer.
What does your own sample show: any improvement fills at all, or is every fill at the clicked price or worse?
The way to find out is boring and cheap: place a few dozen market orders on a liquid pair during active hours, small size, and record clicked price against fill price. Do the same for both buys and sells. Count how many fills are better than clicked, how many are worse, and how large each side is.
A healthy result looks roughly symmetric, with the average slippage near zero and occasional improvements as large as the occasional deterioration. A result where 15 percent of fills are worse by around 0.3 pips and nothing is ever better is telling you something, even though no single fill looks suspicious.
Also check order type. Limit orders typically fill at the limit or better, while market orders carry the slippage in both directions, and stop orders mostly carry it one way. Mixing them in one sample muddies the answer.
What does your own sample show: any improvement fills at all, or is every fill at the clicked price or worse?