Investing term
What is Market order?
Buy (or sell) now at whatever the ask (or bid) is.
A market order buys or sells immediately at the best available price right now — the ask if you're buying, the bid if you're selling. It prioritises speed and certainty of execution over price control: you're telling the broker 'get me in (or out) now, whatever the current price.'
On liquid stocks with a tight spread, that's perfectly fine — the fill will be within a cent or two of what you saw. But on thinly traded securities a market order can fill at a surprisingly bad price by sweeping through the order book, taking each available level until it's filled. Speed is guaranteed; the exact price is not.
A market order takes the best available price immediately — the ask when buying. Fast and certain, but on a thin stock it can sweep the book and fill at a surprisingly bad price.
For example
You place a market buy and it fills instantly at the $20.05 ask — fast and certain, but you took whatever price the market offered.
Learn it by doing
That's Market order in theory — it clicks when you use it. Practise it hands-on in a free, interactive lesson (Stage 5, How Markets Work Globally).
Try the free lesson →Why it matters to you
Market orders matter because their simplicity hides a trade-off: you get guaranteed execution but surrender control over price. For a liquid ETF or a big-company stock, that's a fine bargain — the spread is trivial. For anything thin or fast-moving, a market order can quietly cost you through slippage. Knowing when speed is worth the price uncertainty, and when a limit order is safer, is core order-handling literacy.
⚠ Using market orders on thin stocks
A market order on an illiquid security can fill far from the last quoted price, eating through several order-book levels as it goes — the slippage can dwarf any commission. Reserve market orders for liquid stocks and funds with tight spreads; on thin or fast-moving names, a limit order caps what you'll pay or accept.