Market order
An order to buy or sell immediately at the best available price. It fills fast but you accept whatever price the book offers, including slippage.
Market orders make you a taker, crossing the spread for an instant fill. In a thin Kalshi book that immediacy can be expensive, since you may sweep through several price levels.
A market order is an instruction to trade immediately at the best available price, taking whatever liquidity the order book currently offers. It prioritizes certainty and speed of execution over price: you will get filled right away, but at whatever prices are resting in the book, which may be worse than the last quote if the market is thin.
The appeal is immediacy. When you need to act on time-sensitive information, or to exit a position quickly, a market order guarantees you are done now. The cost is that you take liquidity (paying taker fees) and accept slippage: a large market order in a thin book walks through progressively worse prices, so your average fill can drift well off the top of the book.
Market orders are best reserved for liquid markets or genuinely urgent situations. In thin markets, the same goal is often better served by an aggressive limit order that caps the worst price you will accept, trading a little certainty for protection against a bad fill.
You send a market buy for 300 contracts. The book offers 100 at 60, 100 at 62, and 100 at 65. You are filled instantly across all three levels for a blended price near 62 cents, rather than the 60 you saw at the top, the cost of demanding immediate execution.
Frequently asked questions
What is a market order?
An order to trade immediately at the best available prices in the book. It guarantees a fast fill but not a specific price, so it can cost more than the last quote in thin markets.
When should I use a market order?
When immediacy matters more than price, such as acting on urgent news or exiting quickly, and ideally in liquid markets where slippage is small.
What is the risk of a market order?
Slippage. A large order in a thin book fills across worse and worse prices, so your average fill can be well off the top of the book. An aggressive limit order can cap that risk.