What Is the Ask Price?
Ask price is the lowest price a seller is currently willing to accept, and therefore the price a buyer pays when buying immediately. It sits above the bid price, and a position bought at the ask starts underwater by the width of the spread.
Every quote has two numbers. The ask is the one that applies to you when you are buying, and it is always the higher of the two.
How it works
Sellers post the prices they will accept and the lowest of those is the ask. Like the bid, it is a live standing offer with a real size behind it.
Buy at market and you lift the ask. A market order is an instruction to trade immediately at whatever is available, and what is available to a buyer is the ask.
Which means a new position begins at a loss. You bought at the ask; the position is now marked at the bid; the difference is yours to make back before anything counts as profit.
Walking up the book
The quoted ask is one line of a stack. Above it sit more sellers at higher prices, and a large buy order consumes them in order until it is filled.
So a big order moves the price it is trying to get. The act of buying consumed the cheapest sellers, and the next buyer faces a higher ask because of what you just did.
Which is why institutions break orders into pieces. Not to be clever, but because buying the whole amount at once means paying the price your own order created.
A worked example
Bid 99.95 for 500. Ask 100.05 for 400. Midpoint 100.00, spread 0.10.
Buy 400 at market: you pay 100.05. Mark the position at the bid and it shows 99.95 — down 0.10, or 0.1%, on a market that has not moved.
Buy 2,000 instead. 400 fill at 100.05, then the order eats 100.10, 100.15 and whatever sits above, and the average is materially worse than the quote.
The market did nothing during that. The entire cost came from wanting the full size immediately, and it is invisible on the confirmation because there is no fee line for it.
The alternative is waiting
A limit order posts a price rather than taking one. Bid 99.95 yourself and you join the queue of buyers; if a seller comes to you, you buy at the bid instead of the ask.
You now own the spread rather than paying it — a swing of the full 0.10 in this example, which is twice what the market order cost you.
The trade is certainty. A market order fills now at a known-bad price; a limit order fills at a good price or does not fill at all, and a limit order that misses a move costs far more than a spread.
Which way that trade goes depends on why you are trading. Somebody acting on information cannot wait; somebody rebalancing a portfolio can wait all day, and mostly should.
The original data
On this site’s shared series a round trip costs 0.0098, about 2% of the median bar range of 0.493. The ninetieth percentile bar is 1.101 and the largest is 2.338.
The ask side is half of that. You pay roughly 0.0049 crossing to buy, and the same again to get out.
And this site’s fee measurement shows what small recurring costs do over time: 5 basis points costs 1.5% of a thirty-year final balance, 20 costs 5.8%, 75 costs 20.2%, 150 costs 36.5%. A spread paid frequently behaves the same way — a small number compounding against you.
Why the ask widens
Uncertainty. A seller posting an ask has to price the chance that the buyer knows something they do not. The less visible the near future, the further from the midpoint the ask sits.
Thin participation. Fewer sellers means fewer competing asks, and the lowest of a small set is further from fair value than the lowest of a large one.
Inventory. A market maker already holding too much of something will post a keener ask to shed it, and one holding too little will post a worse one. The quote reflects their position, not only their view.
And event risk. Ahead of a scheduled announcement, spreads widen in advance because nobody wants to be the resting order that a repricing runs over. That widening is itself information: a quote that has gone wide is telling you something is expected.
And tick size. In markets with a minimum price increment, the ask cannot sit closer to the bid than one tick, so in a heavily traded instrument the spread is pinned at that floor and competition shows up as larger displayed size rather than a better price.
When it fails
The characteristic failure is backtesting at the midpoint. A strategy tested on closing prices or midpoints buys and sells at a number that was never available, and the results look fine. Applied live, every trade pays half the spread on entry and half on exit, and a system with a small edge per trade can lose all of it to a cost the test did not model. The strategy did not stop working — it never worked at the prices anybody could actually get.
A second failure is using market orders in thin conditions, where the ask sits far above the last trade and the fill is unpleasant.
A third is assuming the displayed ask applies to your size. It applies to the size shown beside it and no more.
A fourth is measuring execution quality against the midpoint, which was never obtainable.
And a fifth is trading frequently in something with a wide spread. The cost scales with how often you cross it, and a wide spread crossed often is a larger drag than almost any fee.
Related
Bid price covers the other half of the quote. Bid-ask spread covers the gap and what sets its width. And market order covers the instruction that pays it.
Buy at the ask and sell at the bid and you have lost the spread before the market has done anything at all. That is not a fee anybody charges you and it is not optional — it is the price of wanting to trade now instead of waiting.
— Michael Whitman
This page is educational, not financial advice. Test every idea on your own charts before risking money.