Most people who discover zero-commission brokers think they’ve cracked the code on free trading. They haven’t. Every single trade carries a built-in cost called the bid-ask spread — and on certain securities, it dwarfs what anyone paid in commissions years ago. Understanding this one concept separates investors who know their real costs from those who don’t.
What the Bid-Ask Spread Actually Is
The Two Prices Behind Every Quote
When you look up a stock, you’ll see two prices: the bid and the ask. The bid is the highest price any buyer is currently willing to pay. The ask — also called the offer — is the lowest price any seller will accept. The spread is simply the gap between them.
If Apple (AAPL) shows a bid of $189.50 and an ask of $189.52, the spread is $0.02. Two cents per share. Small for a liquid mega-cap. But that number grows dramatically on smaller, less-traded securities. On thinly traded small-caps or penny stocks, spreads of $0.25, $0.50, or $1.00 per share are normal — a cost you absorb before the stock moves a single tick in your direction.
When you place a market buy order, you pay the ask. When you place a market sell, you receive the bid. The market maker — the intermediary sitting between you and the other side — keeps the difference. Every time.
Who Actually Profits From the Spread
Market makers are firms that continuously post bid and ask prices, standing ready to buy or sell instantly. They provide liquidity — the ability to exit a position right now without waiting for a matching buyer. That service isn’t free.
On US exchanges, dominant market makers include Citadel Securities and Virtu Financial. These firms process millions of trades daily, earning fractions of a cent on each — adding up to billions per year. That revenue comes from spreads. Your spreads. For liquid securities like SPY (the world’s most traded ETF), the spread is often $0.01. For a thinly traded biotech or a penny stock, the same mechanics produce spreads that can consume 5–30% of your position value on entry alone.
How Much the Spread Is Actually Costing You
When you buy at the ask and sell at the bid, you start every trade in the red by the full spread — before the stock moves at all. Here are real numbers across different security types:
| Security | Bid | Ask | Spread | Spread % of Price | Cost on 200-Share Trade |
|---|---|---|---|---|---|
| SPY (S&P 500 ETF) | $510.00 | $510.01 | $0.01 | 0.002% | $2.00 |
| AAPL | $189.50 | $189.52 | $0.02 | 0.011% | $4.00 |
| Mid-cap stock (avg) | $24.80 | $24.90 | $0.10 | 0.40% | $20.00 |
| Small-cap biotech | $8.20 | $8.50 | $0.30 | 3.5% | $60.00 |
| Penny stock | $0.85 | $1.10 | $0.25 | 23% | $50.00 on $220 invested |
That penny stock example is not hypothetical. Spreads on sub-$1 stocks routinely eat 10–30% of position value the instant you enter. Buy 200 shares at $1.10 ($220 total), and if the stock holds flat, you sell at $0.85 and recover $170. A 23% loss on a completely motionless market.
Day Traders Feel This Most Sharply
Make 10 round-trips per day in a moderately illiquid stock with a $0.20 spread, buying 500 shares each time, and you’re paying $100 per round-trip in spread costs — up to $1,000 per day just to participate. The stock needs to move significantly before you see a dollar of profit. This hidden drag is a primary reason most retail day traders underperform or lose money even when their directional calls are right. They account for commissions. They don’t account for this.
What Makes Spreads Wide or Narrow
Five factors determine how much a spread costs you on any given trade. Know these and you’ll spot expensive trades before you click buy.
- Trading volume. High volume equals tight spreads. SPY trades hundreds of millions of shares daily, with dozens of market makers competing for flow — spreads collapse to a penny. A stock trading 50,000 shares per day has far fewer competing market makers, so spreads stay wide and execution quality drops.
- Stock price. Always think in percentages, not absolute cents. A $0.30 spread on a $1 stock is 30%. On a $100 stock, that same spread is 0.3%. The dollar amount of the spread tells you almost nothing without knowing the stock price.
- Volatility. During earnings releases, Federal Reserve decisions, or broad market stress, spreads widen fast. Market makers holding inventory take on more risk in volatile conditions, so they charge more to provide liquidity. During March 2026, spreads on normally liquid ETFs blew out five to ten times their typical levels within hours of the open.
- Time of day. The first and last 30 minutes of the trading day carry wider spreads. At open, overnight news gets priced in with urgency. Near the close, institutions aggressively adjust positions. The tightest window is typically 10:00–11:30 AM Eastern — the most orderly, liquid part of the session.
- Asset type. Options carry spreads that routinely run 5–20% of contract value. ADRs (foreign stocks on US exchanges) and niche sector ETFs also carry hidden spread costs that don’t appear as a visible fee but hit your real returns on every transaction.
The Mistake That Costs New Traders the Most
Market orders on illiquid stocks are how traders lose money they never see leaving their account.
A market order executes at whatever the current price is. On liquid stocks like AAPL or SPY, that’s completely fine — the spread is negligible. But on a small-cap with a wide spread, a market order guarantees you buy at the ask and sell at the bid. Full spread. Every time. No exceptions.
The Scenario That Surprises People
A stock shows a bid of $5.00 and an ask of $5.40. You place a market buy for 200 shares. You pay $5.40 per share — $1,080 total. The stock holds flat all afternoon. You sell. You receive $5.00 per share — $1,000 total.
You lost $80 on a completely flat stock. No commission. No fee. Just the spread. That’s 7.4% of your capital gone before the market moved against you at all. New traders often blame the stock. The order type is what did it.
Limit Orders Solve This — With One Real Tradeoff
A limit order specifies the maximum price you’ll pay. Limit buy at $5.15 on that same stock and you’ve cut the spread impact significantly — if it fills. The tradeoff is genuine: sometimes the order doesn’t fill and the stock moves without you.
For patient investors, that tradeoff almost always favors limit orders. Missing a trade costs you opportunity on one position. Consistently eating the full spread on every trade costs you real dollars compounding across hundreds of transactions. Those two outcomes trend in opposite directions over time.
Market Orders vs. Limit Orders: Your Questions Answered
Should I always use limit orders?
For high-volume stocks and ETFs — SPY, QQQ, AAPL, MSFT — market orders are perfectly fine. The spread is $0.01 and the main risk is failing to fill during a fast-moving session. Switch to limit orders for anything trading under 1 million shares per day, and for all options trades without exception.
What about options specifically?
Always use limit orders on options. Always. Bid-ask spreads on options routinely run $0.10–$0.50 wide. On a $1.00 contract, that’s 10–50% of the position’s value lost on entry. Market orders on options at the open are one of the fastest ways to overpay in all of investing.
The thinkorswim platform — now part of Charles Schwab following the TD Ameritrade acquisition — displays “Natural” and “Mid” prices directly in the options chain. The midpoint between bid and ask is your starting limit price. Place the order there, wait 30 seconds, nudge toward the ask if no fill. Active options traders who adopt this habit routinely save $200–500 per month on execution costs compared to hitting market orders reflexively.
Does the spread matter for long-term investors?
Mostly no. Buying SPY or VOO and holding for 15 years? A $0.01 spread is statistically invisible against 15 years of compounding. But if you hold a thinly traded bond ETF or niche thematic fund with a $0.15 spread and rebalance quarterly, those costs accumulate across years of transactions.
The cleanest fix for long-term investors: stick to high-volume ETFs — SPY, VOO, and VTI all trade at penny spreads. Or go one step further with Fidelity’s FZROX (total US market) and FZILX (international). These are zero-expense mutual funds priced at end-of-day NAV. No bid. No ask. No spread. You get in and out at fair value, full stop.
When the Spread Is Simply Not Worth Thinking About
If your strategy is buying SPY, VOO, or VTI and holding for years, the spread genuinely does not matter. That’s not hedging — it’s math. A one-time $0.01 cost across a decade of compounding is immeasurable. Reserve your attention for spreads when your spread-to-price ratio exceeds 0.5%, or your average holding period is under six months.
How to Check the Spread Before You Trade
Step 1: Pull the Bid and Ask Before Placing Any Order
Every brokerage platform shows Level 1 quotes: current bid price, ask price, and last trade. In Fidelity’s Active Trader Pro, these update in real time on any watchlist. In Interactive Brokers’ Trader Workstation (TWS), bid and ask are default columns in every view. Even Robinhood surfaces bid and ask in the stock detail screen if you scroll to the market data section — it’s there, just not front and center.
Step 2: Calculate Whether the Spread Is Significant
Divide the spread by the ask price. A $0.10 spread on a $50 stock = 0.2%. Acceptable. That same $0.10 spread on a $3 stock = 3.3%. Significant. If the ratio is above 0.5%, use a limit order. If it’s above 2%, reconsider whether this trade makes sense at current prices at all.
Step 3: Check Volume With a Free Tool
Webull’s free mobile app (iOS and Android, no account deposit required) shows average daily volume on every stock’s detail screen — no login friction. Under 500,000 shares per day means you’re in wider-spread territory. For deeper visibility, Interactive Brokers offers free Level 2 market data for active traders, showing the full order book — who’s bidding what, at which price levels, and how many shares deep. Knowing the actual depth of liquidity tells you whether your order fills smoothly or sits waiting in a thin market.
Step 4: Place the Limit Order at the Midpoint
For a buy, start your limit at the midpoint between bid and ask. Stock with a $24.80 bid and $24.90 ask? Try $24.85. Wait 30–60 seconds. No fill? Move up one cent. This approach regularly gets fills at or near the mid rather than at the full ask — on a 500-share order, that’s $25 saved in a single trade. Done consistently across an active year of investing, the savings are meaningful and real.
Trading costs have never been more invisible — and that invisibility is exactly why they matter more now than when brokers charged $9.99 a trade. With commissions gone, the spread is where the real economics of execution live. As retail access to markets deepens and more assets become tradeable — crypto, fractional shares, micro-futures — bid-ask spreads will only grow in importance as the friction that separates disciplined traders from everyone else.
Disclaimer: The information on this page is for educational purposes only and does not constitute financial advice. Rates, terms, and eligibility requirements are subject to change. Always compare multiple lenders and consult a licensed financial advisor before borrowing.
