// GLOSSARY

IOC order (immediate-or-cancel)

An order that fills whatever it can against the book right now and cancels the remainder — it never rests. The standard way to take liquidity with a price cap: you get immediacy without leaving a stale order behind.

An immediate-or-cancel order is a limit order with no patience: it matches against whatever the book offers at or better than your limit, and anything unfilled is cancelled instantly instead of resting.

Worked example

The book shows 300 contracts at 44¢ and 500 at 46¢. You send an IOC buy for 1,000 limit 45¢. You fill 300 at 44¢; the 46¢ level is beyond your limit, so the remaining 700 are cancelled. You took the liquidity you were willing to pay for and left nothing exposed.

When to use it

IOC is the taker's tool of choice when you want immediacy with price protection — a market order gives immediacy with none. It's also the natural primitive for cross-venue routing: probe one venue's book at your cap, see what fills, route the remainder elsewhere. Support and exact semantics vary by venue (Kalshi and Polymarket each document their time-in-force options — verify against current docs); the landscape is mapped in rate limits and order types.