Market on Close (MOC)

A MOC order is just a market order with a clock on it: fill me at the end of the session, whatever the market is doing then. The one trap the exam sets is confusing "at the close" with "at the settlement price," so hold those two apart.

What a MOC Order Is

A MOC order takes the plain market order and times it to the final moments of trading.

• Market on close (MOC) order: a market order that is executed at or near the close of the trading session, within the closing range (at prevailing prices during the final moments of trading).
• Guarantees participation, not a price: MOC guarantees the order takes part in the close. It does not guarantee a specific price. The customer is choosing to trade at whatever the market is doing at the end of the session rather than naming a price.
• Fills within the closing range: because it fills at prevailing end-of-session prices, a MOC order lands somewhere in the closing range, close to but not necessarily equal to any single reference number.

At the Close Is Not the Settlement Price

This is the whole reason a MOC question is on the exam, so make the distinction sharp.

• The close is a window; the settlement is a number: MOC fills at the prevailing price during the closing range, which is a span of trading at the end of the session. The official settlement price is a specific figure the exchange determines for the day.
• The fill may or may not equal settlement: because a MOC order fills at whatever the market offers in the closing range, the executed price may or may not equal the official settlement price. Trading "at the close" (participation) is not the same as being filled "at settlement" (a specific price).

Think of it this way: a MOC order is like telling a taxi driver "just get me there by closing time, at whatever the meter says when we arrive." You are guaranteed to arrive before the doors shut, but you have handed the meter the power to set the fare. The official settlement price is like the posted average fare for that route, a single published number. What you actually pay lands near it, in the same neighborhood, but it is set by the trip you took, not by the posted figure.

Exam Tip: Gotchas

• MOC guarantees the close, not the settlement price. It is a market order timed to the end of the session, so the fill can differ from the official settlement. If a choice says MOC "locks in the settlement price," it is wrong.
• MOC is still a market order. Like any market order, it guarantees a fill, not a price. The "on close" part only controls the timing (the end of the session); it does not turn the order into a promise of one specific price.

Why Traders Use It

MOC exists for traders who want their fill to reflect the session's ending level and want to be sure they are in or out by the close.

• Be in or out by the end of the day: MOC ensures a position is entered or exited by the end of the session at the market's closing level, without leaving an unfilled limit order that might expire.
• Fill at the session's final level: it suits traders who want their execution to reflect the closing price action rather than an intraday level partway through the day.