The Gap Between What You Expected and What You Got
You see a stock at $10.50. You click buy. Your fill comes back at $10.63.
That $0.13 difference wasn’t a commission. It wasn’t a fee. It was slippage, the gap between the price you expected when you placed the order and the price you actually received when it executed.
It showed up on nothing. It was deducted from nothing. It just silently made your trade $130 worse than you planned on a 1,000-share order. And if your profit target on that trade was $0.30, slippage just cut your potential gain by 43% before the market moved a penny in either direction.
Slippage is not rare. It is constant. And for active traders, particularly those trading fast-moving, volatile stocks, it is often the single largest drag on otherwise profitable strategies.
What Causes Slippage
Market orders in fast markets. A market order says “fill me at any price.” In a stock that’s moving rapidly, the price can shift significantly between when you click and when your order reaches the exchange. In a low-float runner moving $0.50 per minute, a market order can fill $0.20–$0.50 away from the quoted price.
Low liquidity. Thin order books mean fewer orders sitting at each price level. A large order eats through available liquidity quickly, moving the price as it fills. The fewer participants in a stock, the worse the slippage.
Wide bid-ask spreads. A market order fills at the ask. If the ask is $0.20 above the bid, you’re starting $0.20 underwater immediately. This is the spread component of slippage. See our article on Why Bid-Ask Spreads Matter More Than Commissions for a full breakdown.
Stop loss orders in gapping markets. A stop loss at $9.00 doesn’t guarantee a fill at $9.00. If the stock gaps from $9.50 to $8.80 on news, your stop market order fills at $8.80, $0.20 below where you expected. Stop loss slippage is worst during earnings gaps, news events, and pre-market/after-hours sessions.
Order size relative to average volume. Trying to buy 5,000 shares of a stock averaging 50,000 daily volume means your order represents 10% of typical daily activity. You will move the price as you fill. Your average entry will be significantly worse than the price you saw when you decided to trade.
How Slippage Destroys Otherwise Profitable Strategies
A strategy that captures $0.15 per share on average in backtesting can fail in live trading with $0.08 average slippage. The backtest assumed fills at quoted prices. Live trading fills at worse prices. The strategy was never as profitable as it appeared.
This is one of the most common reasons traders fail to replicate backtested results in live trading. The backtest is clean. Live execution has friction. Slippage is the largest component of that friction.
For scalping strategies, capturing very small moves on high volume, slippage is often the difference between viability and impossibility. A strategy targeting $0.05 per share is simply incompatible with $0.06 average slippage. The math doesn’t work, regardless of the win rate.
How to Minimize Slippage
Use limit orders. A limit order guarantees price, not execution. You won’t fill at a worse price than your limit. But you may not fill at all. For most non-urgent entries, this trade-off is favorable. See our Limit Orders article for full guidance.
Trade liquid stocks. The single most effective slippage reducer. Stocks with high daily volume, tight spreads, and deep order books fill closer to quoted prices because there are always buyers and sellers at every price level.
Size appropriately. Don’t trade position sizes that represent a significant percentage of typical daily volume. A rough guide: keep individual orders below 0.5–1% of average daily volume to avoid meaningful market impact.
Avoid market orders on momentum stocks. The fast, volatile stocks that produce the biggest moves also produce the most slippage on market orders. If you trade these stocks, use limit orders placed aggressively (close to the ask for buys) rather than market orders.
Trade during peak hours. Liquidity is highest during the main session (9:30 AM–4:00 PM EST), with the best conditions typically in the first and last hours. Pre-market and after-hours sessions have dramatically wider spreads and worse fills.
Use a direct-access broker. Brokers that route orders directly to exchanges, like Cobra Trading, Interactive Brokers, and TradeZero, give you more control over execution quality than brokers using payment for order flow. Your orders go to the exchange, not through a market maker who profits from filling you at a worse price.
The Honest Accounting
The traders who succeed long-term are the ones who account for all of their costs, not just the ones that appear on statements. Slippage doesn’t appear on your statement. It appears in the difference between your expected P&L and your actual P&L.
Track it. On every trade, note the price you saw when you decided to enter and the price you actually got. Calculate the difference. Over 30 days, you’ll have a clear picture of what slippage is actually costing you and whether your current approach to stock selection and order entry is serving you well.
What you measure, you can manage. What you ignore keeps costing you.
All investing involves risk. This article is for educational purposes only and does not constitute financial advice.