Market-on-Close (MOC)

A Market-on-Close (MOC) order is an instruction to buy or sell a security at the best available price during the closing auction or at the official closing price of the trading session, rather than at any specific price during the regular session. MOC orders guarantee execution at the day's closing price but do not guarantee a specific price. In Indian equity markets, NSE and BSE conduct a closing price call auction session from 3:30 PM to 3:40 PM IST — during which orders accumulate and are matched at a single equilibrium closing price. Institutional investors — particularly index funds, ETFs, and mutual funds that track market benchmarks — use MOC orders to rebalance their portfolios at the official closing price used to calculate their NAV, ensuring minimal tracking error. For portfolio managers, executing at the closing price is important for benchmark alignment and performance attribution. MOC orders must be placed within the designated pre-close window and cannot be modified or cancelled after the session begins.