The Bid-Ask Spread: The Fee Nobody Puts on Your Statement

The Bid-Ask Spread: The Fee Nobody Puts on Your Statement

You buy 100 shares. The confirmation shows $0 commission. You check the price a minute later and you’re already down money, and nothing happened in the market. No news, no drop, no reason. You just bought and sold at two different prices, and the difference went to someone else.

That someone else is usually a market maker, and the gap you paid is the bid-ask spread. It doesn’t show up as a line item anywhere on your statement. It’s baked into the price itself, which is exactly why most new traders don’t notice it until they add up a few dozen trades and wonder where the money went.

What the bid and ask actually are

Every tradable security has two live prices at any moment, not one.

The bid is the highest price someone is currently willing to pay for the security. The ask (sometimes called the offer) is the lowest price someone is currently willing to sell it for. If you want to sell right now, you get the bid. If you want to buy right now, you pay the ask. The ask is always higher than the bid — that gap is the spread.

Say a stock shows a bid of $50.00 and an ask of $50.10. Buy at market and you pay $50.10. Turn around and sell at market one second later, with the quote unchanged, and you get $50.00. You just lost ten cents a share without the stock moving at all. That’s not a fee your broker charges you. It’s the cost of demanding immediacy in a market where someone else has to be willing to take the other side.

Who collects it, and why

Market makers and other liquidity providers post both the bid and the ask. They make money on the spread itself, buying at the bid and selling at the ask, over and over, across thousands of trades a day. It’s compensation for standing ready to trade with you instantly, in either direction, whenever you show up. The SEC’s Office of Investor Education and Advocacy publishes material explaining how orders route and execute in modern markets, and the spread is a core part of that mechanism, not a glitch in it.

Widen the lens and the logic makes sense. A market maker holding inventory takes on risk. The stock could move against them before they offload it. The spread is their payment for absorbing that risk on your behalf, right now, instead of making you wait for a matching buyer or seller to show up on their own.

A worked example

Assume a trader buys 100 shares of a mid-cap stock with a $50.00 bid and $50.10 ask, then decides to sell out of the position five minutes later with the quote unchanged.

Ten dollars on a $5,010 position is about 0.20%. That doesn’t sound dramatic until you notice it’s a cost you pay just for entering and exiting, before the stock has to move a single cent in your favor for you to break even. A trade needs to gain roughly 0.2% just to cover the spread, on top of whatever profit target the trader actually has in mind.

Now compare a thinly traded small-cap with a wider spread: a $10.00 bid and a $10.15 ask.

Same dollar amount invested, roughly. But the spread cost jumps to about 1.5% of the position, seven times worse than the mid-cap example, purely because the stock is less liquid. These figures are illustrations built from assumed quotes, not live market prices, and real spreads move throughout the trading day.

What widens or narrows a spread

Spreads aren’t fixed. A handful of things push them around:

Liquidity. Heavily traded names with millions of shares changing hands daily tend to have spreads measured in pennies or fractions of a penny. Thinly traded names can have spreads that are a meaningful percentage of the price.

Volatility. When a stock is swinging hard, market makers widen spreads to protect themselves from getting caught on the wrong side of a fast move. Spreads around earnings announcements or major economic releases are routinely wider than on a quiet Tuesday.

Time of day. Spreads tend to be tighter during the core trading session and wider right at the open, right at the close, and especially in pre-market and after-hours trading, when fewer participants are active.

Market cap and float. Smaller companies with fewer shares available to trade generally carry wider spreads than large, widely held ones.

How the spread interacts with order type

A market order accepts whatever the current bid or ask happens to be the instant it executes. A limit order lets you name your price instead, which means you can choose to buy somewhere inside the spread, or even at the bid, rather than paying the ask outright. The trade-off is that a limit order isn’t guaranteed to fill; if the market moves away before someone takes the other side, nothing happens. The Financial Industry Regulatory Authority publishes investor education material on order types that covers this trade-off between execution certainty and price control in more depth than a single article can.

Most trading platforms show the current bid, ask, and spread on the quote screen before you place an order. Checking it takes five seconds and tells you exactly what a round-trip trade will cost you before you commit to it.

What this does not tell you

This article covers the mechanical cost of crossing the spread on a single round trip. It doesn’t cover several things that matter for a real trading decision.

It doesn’t account for commissions, exchange fees, or regulatory fees, which some brokers still charge on top of the spread even when the advertised commission is zero. It doesn’t cover slippage, which is the additional cost of an order moving the market against you when the order size is large relative to available liquidity at the quoted price — a separate problem from the spread itself, though related. It doesn’t address whether trading frequently is a sound strategy in the first place; that depends on goals, time horizon, and risk tolerance that vary by individual and aren’t something a mechanics article can evaluate for you. And it uses static, assumed quotes for illustration. Real bid-ask prices update continuously, sometimes many times a second in liquid markets, so an actual trade’s spread cost will differ from any example built on frozen numbers.

FAQ

Does the bid-ask spread apply to mutual funds?

No, not in the same way. Traditional open-end mutual funds transact once a day at net asset value, so there’s no live bid and ask to cross. Exchange-traded funds, however, trade throughout the day like stocks and do have a bid-ask spread, which can be wider or narrower depending on the ETF’s own trading volume and the liquidity of its underlying holdings.

Is a zero-commission broker really free?

Commission and spread are two separate costs. A broker can charge no commission while you still pay the spread on every trade, since the spread exists in the market itself, not in the broker’s fee schedule. Some brokers also generate revenue through payment for order flow, which is a separate topic worth understanding on its own; the SEC’s investor page is a reasonable starting point for how order routing works.

Can the spread ever work in a trader’s favor?

Not directly for someone placing individual market orders, no. The spread is structurally a cost to whoever needs immediate execution. A trader using limit orders can sometimes get filled at a price better than the prevailing market order price, effectively capturing part of the spread instead of paying it, but that requires patience and isn’t guaranteed to fill at all.

Why do options often have much wider spreads than stocks?

Options generally trade less frequently than the underlying stock, and there are far more individual contracts (different strikes and expirations) splitting that trading activity. Less volume concentrated in each specific contract usually means wider spreads, sometimes substantially wider than the underlying stock’s own spread.

How do I find the current spread on something I’m watching?

Most brokerage platforms display live bid and ask prices, often labeled “Level 1” data, right next to the last traded price on a quote screen. Checking that before placing an order shows the exact cost of trading immediately versus using a limit order.

What to look at next

Anyone curious about this might look at how their own broker displays bid and ask prices before an order goes in, and compare the spread on a large, widely traded stock against a smaller, thinly traded one to see the difference firsthand. It’s also worth reading about how limit orders and market orders differ in execution guarantees, since that choice directly determines whether the spread is paid in full or partly avoided.

This article is general information, not financial advice. See our disclaimer.