Most traders obsess over direction and ignore execution. That is a mistake. The price you pay to enter and exit is a real cost. Spreads, slippage, and poor fills slowly bleed an account even when your idea is right.
The Core Idea
Every market has two prices.
- Bid: the highest price buyers will pay.
- Ask: the lowest price sellers will accept.
The gap is the spread. Cross the spread and you pay a toll. Do it often and it adds up.
What Moves the Spread
- Liquidity: more volume and tighter order books mean smaller spreads.
- Volatility: fast markets widen spreads.
- Time of day: open and close are jumpy. Midday is usually calmer.
- Product: mega caps and liquid option expiries are tight. Thin names are not.
Why Slippage Happens
Slippage is the difference between the price you wanted and the price you actually get.
- Market orders eat through the book.
- News spikes pull quotes away from your limit.
- Large size in a thin market pushes price against you.
How Fills Really Work
- Market order: fastest, worst control. You take whatever is there.
- Limit order: price control, patience required. You post liquidity and get paid in tighter costs.
- Mid-price tactics: start near the midpoint, then nudge in small steps if you are not filled.
Simple Math That Hurts
- Stock example: spread is 2 cents. You buy 5,000 shares by crossing. Cost is $100 in spread. Do that 20 times a month and it is $2,000.
- Options example: a contract is $1.00 by $1.10. Cross the spread on 10 contracts and you pay $100 just to get in. Round trip is $200 if you also cross to exit. Your PnL must beat that before you see a profit.
Better Fills, Step by Step
- Choose liquid tickers and expiries. Tight spreads save more than clever entries.
- Use limits. Start at mid. If no fill, improve by small increments.
- Trade during liquid hours. Avoid the first and last minute unless you must.
- Scale in and out. Split orders. Partial fills reduce slippage risk.
- Avoid chasing. If price runs, let it go or reset the plan. Chasing is how spreads tax you twice.
- Size to the book. Do not slam 2,000 shares into a thin ladder. Work the order.
- Know event risk. Spreads balloon into earnings and news. Consider waiting or using spreads in options to sell part of the premium.
A Quick Playbook for Options
- Prefer strikes with tight spreads and real size at bid and ask.
- If IV is elevated, consider debit or credit spreads to reduce effective slippage.
- When closing, try working a limit toward mid rather than smashing the bid.
What to Track
- Average spread paid per trade.
- Average slippage from intended to actual fill.
- Win rate after costs.
If your edge disappears after costs, adjust execution before you change the strategy.
Final Thoughts
Execution is not exciting, but it is where real traders separate from gamblers. Tighten the spread you pay, control slippage, and work your orders with intention. Do that, and the same ideas you already trade start paying more with less drama.