A limit-on-close (LOC) order participates in the closing auction only if the closing price is at or better than your limit — combining closing-auction execution with price protection. It’s the priced version of the MOC.

How it works

Like an MOC, an LOC is entered before the close cutoff and aims to execute in the closing auction — but it carries a limit price. If the official close is at or better than your limit, you fill; if not, you don’t. So you get the closing print only at an acceptable price, trading guaranteed execution for price control.

MOC vs LOC

An MOC guarantees you’re in the close at whatever the price is; an LOC guarantees your price but may not fill. It’s the same market-vs-limit tradeoff, applied to the closing auction. Institutions use LOCs when they want the close but won’t accept an adverse price.

MOC takes the close no matter what; LOC takes the close only if the price is right. Certainty of fill vs certainty of price, at the bell.

The takeaway

LOC orders are institutional tools for the closing auction with price protection — niche for a scalper, but part of understanding how the close and its imbalances work. The mechanics of the auction itself are covered in the closing auction explained.