fill or kill

A fill or kill (FOK) order is "an order to buy or sell a stock that must be executed immediately"—a few seconds, customarily—in its entirety; otherwise, the entire order is cancelled; no partial fulfillments are allowed.{{cite web|title=Fill-Or-Kill Order|url=https://www.sec.gov/answers/fokord.htm|publisher=U.S. Securities and Exchange Commission|accessdate=22 March 2013|date=10 March 2011}}

Characterized as "extreme orders", FOK orders are "most commonly used when your order is for a large quantity of stock and is usually a market or limit order that requires immediate execution".{{cite web|title=Extreme Orders for Everyday Investors|url=http://research.scottrade.com/public/knowledgecenter/knowhownews/intheknow.asp?nlid=633ec37e00b5404eba061447da9b5b34|publisher=Scottrade Knowledge Center|accessdate=22 March 2013|date=May 2009}} They are also used when several unlinked markets are available for the same asset, in which case the trader will try to get the whole order filled in each market sequentially, without having to manually cancel each order if it is unfilled.{{Cn|date=August 2021}}