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Order Types
What Is a Market-on-Close (MOC) Order?
The MOC order is how big money guarantees a fill at the official closing print — and the imbalances it creates can move the last minutes of the day.
NoVo Options Trading · 2026
A market-on-close (MOC) order executes at the official closing price, guaranteeing participation in the closing auction. It’s a tool used mostly by institutions to get the closing print.
How it works
An MOC is an unpriced order to buy or sell at the close. It must be entered before a cutoff (around 3:50pm ET on the NYSE) and is guaranteed to execute in the closing auction at the closing price. Funds, index trackers, and rebalancers use MOCs to trade at the official close rather than risk moving price with earlier orders.
Why it matters to a trader
The aggregate of MOC orders creates a closing imbalance — more buy or sell MOCs — which exchanges publish into the close. A large imbalance can push the last minutes of the day in that direction (a big buy imbalance can lift the close). It’s part of why the close can move sharply, on top of charm/gamma flows.
MOC orders are how institutions lock in the official close — and their imbalance is a real force on the final minutes of the tape.
The takeaway
You likely won’t use MOCs as a scalper, but knowing they exist explains end-of-day imbalance moves. The published MOC imbalance is a genuine late-day tell. Its priced cousin is the limit-on-close (LOC) order.
More on this: Buy to Open, Sell to Close, Sell to Open, Buy to Close: The Four Options Actions
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NoVo is a software tool for market analysis and for executing trades you initiate, not financial advice. This article is general education, not investment advice. Options trading involves substantial risk of loss, up to and including your entire capital. NoVo makes no guarantee of profit, win rate, or performance, and past results do not predict future outcomes. You are responsible for your own broker account, configuration, and trading decisions.