I am trying to understand the difference between FOK and IOC orders. If I send a market FOK or IOC order to sell 100 shares of StockX - what would happen if the orderbook looked like this?

50 @ 300
25 @ 301
100 @ 302
  • 2
    $\begingroup$ 1. You have to specify the price in IOC order, although this can depend on the trading venue. 2. If you want to sell, you should be more concerned about the bid side of the orderbook. Also, it seems to me that the title of question is misleading compared to the question you are asking $\endgroup$
    – nimbus3000
    Feb 3, 2021 at 16:57
  • $\begingroup$ (I suppose it is matter of taste, but I find it confusing to see a limit order book with the prices increasing downward. I feel I should turn my computer upside down ;) to see what is going on). $\endgroup$
    – nbbo2
    Feb 3, 2021 at 17:15

1 Answer 1


Generally FOK means Fill Entirely or Cancel. IOC means "Fill what you can and then cxl the remainder"

  • $\begingroup$ yup what I wanted to know is in the case of the order book that I posted above, how would FOK and IOC behave? $\endgroup$
    – assangar
    Feb 8, 2021 at 11:52
  • $\begingroup$ You are showing the sell side of the book. That doesn't matter. What matters is the bid side of the book. Your order will sweep the market (or route to away markets if they have better prices) $\endgroup$
    – JoshK
    Feb 8, 2021 at 22:15
  • $\begingroup$ Practices can vary in different markets too. I've seen in several energy markets that brokers/everyone says FOK when they mean IOC (and have never heard of IOC). It can be rather frustrating. $\endgroup$
    – RomnieEE
    Jul 26 at 0:24

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