Slippage and Execution Costs in Futures Trading

Anyone who has moved from a backtest to live trading knows the moment: the strategy was supposed to enter at one price, and the fill came back at another. That gap, together with commissions and exchange fees, is your execution cost, and it is one of the quietest forces eroding results. This article breaks execution cost into its parts, shows how to measure them, and covers what you can do to reduce them.

What slippage is

Slippage is the difference between the price you expected and the price at which your order was actually filled. If a strategy sends a buy order while NQ trades at 20,000.00 and the fill arrives at 20,000.75, you slipped three ticks against you. Slippage can also work in your favor, but with market orders in fast conditions it tends to be negative.

It is important to understand that slippage is not a "glitch". It is a natural consequence of how the order book works: every price level holds a limited number of contracts. When you demand immediate execution, you take what is available, and if the first level is too thin or the price moves before your order arrives, you get a different price.

Order types and how they affect execution

The order type is the first decision that determines how much slippage you absorb.

• Market order: guarantees execution, not price. Useful when getting in or out right now matters, but fully exposed to whatever slippage the market delivers.
• Limit order: guarantees your price or better, not execution. No negative slippage, but the price may touch and run away without filling you, or fill you only partially.
• Stop order: becomes a market order once the price touches the level. That is why a stop-loss during a sharp move can fill well beyond the level you set.
• Stop-limit order: caps the fill price after triggering, but in an extreme move it may not fill at all, which is especially dangerous when exiting a losing position.

There is no single "right" order type. A breakout strategy usually needs certainty of execution, while a strategy that enters on a pullback to a level may work with limits. The choice should be deliberate and documented, not a default.

Spread, liquidity and market impact

The bid-ask spread is the gap between the highest price a buyer is willing to pay and the lowest price a seller will accept. In liquid contracts like ES or NQ during the main session the spread is usually one tick, but overnight, around the open, or in thinner contracts it can widen.

Liquidity is the number of contracts available around the current price. The larger your order relative to that liquidity, the more price levels it "eats". This is called market impact. For a trader with one or two MNQ contracts the effect is negligible most of the time, but someone copying orders to several accounts at once is effectively placing a bigger order, and then it starts to matter.

Liquidity changes through the day. It pays to know the futures trading sessions and to remember that the market at three in the morning behaves very differently from the first half hour of the regular session.

News, volatility and latency

Around major economic releases the book can empty out in a fraction of a second. Buyers and sellers pull orders, the spread widens and price jumps several levels at once. A market or stop order sent at that moment can fill far from where you expected. That is why many traders, and some prop firms, avoid new entries in the minutes before and after important releases. Check your firm's rules in its official help center.

Latency is the time from the moment a signal is created to the moment the order reaches the exchange. An automated chain has several links: alert generation, webhook delivery, order processing and the broker connection. Each link adds time, and in a fast market every millisecond is a chance for the price to move. This is one reason some traders choose to run strategies on their own server in a region close to the exchange.

Commissions and exchange fees

Beyond slippage, every trade carries direct costs: broker commission, exchange fees, clearing fees and sometimes platform or data fees. Per contract these are small, but a strategy that trades many times a day feels them clearly. Calculate the total cost per round turn (entry plus exit) and include it in every historical test.

A hypothetical example: suppose the all-in round-turn cost is a fixed amount X and a strategy makes ten trades a day. Over a trading month of about twenty days that is two hundred trades, or 200X in costs, before a single tick of slippage. If the average profit per trade in the backtest is close to X, the live strategy may be break-even or losing.

How to measure slippage in your own log

You cannot improve what you do not measure. Here is a simple process:

1. For each trade, record the price the signal "intended": the close of the bar that produced the signal, or the limit or stop level.
2. Record the actual fill price from your broker statement.
3. Compute the difference in ticks, with a sign: positive in your favor, negative against you.
4. Record the time, order type, position size and whether a news release was nearby.
5. After a few dozen trades, average the slippage by time of day and by order type.

The result might show, for example, that entries at the open cost you more than mid-day entries, or that stops fill further away than profit-taking exits. That is information you can act on. Feed the same number back into your testing; there is more on that in the article on backtesting vs live trading.

Ways to reduce execution costs

• Pick the order type that fits the strategy, not the one you use out of habit. Check whether some entries can be limits.
• Avoid trading in thin windows or around news unless the strategy is designed for it.
• Use micro contracts when you need finer sizing, and split large orders where needed.
• Shorten the execution chain: fewer links, less waiting, and a stable server.
• Include slippage and fees in your tests as a conservative assumption, so your expectations stay realistic.
• Review the data regularly, because market conditions change and what is true today may not hold six months from now.

Key takeaways

• Slippage is a built-in part of trading, not a bug. It comes from liquidity, market speed and order type.
• Market and stop orders are exposed to slippage; limit orders are exposed to not filling.
• News and low-liquidity hours widen the spread and raise the risk of distant fills.
• Commissions and exchange fees add up fast in high-frequency strategies.
• Measure slippage in your log by time and order type, and feed the numbers back into your tests.

WeCore executes signals from TradingView or your own strategies directly on your broker or prop-firm account, and the engine can also run on a cloud server in your own account. A sensible first step is simulation mode, comparing fill prices to signals before moving to a live account.