Market on Close (MOC) Order¶
A market on close (MOC) order guarantees execution at the official closing price of a stock's primary exchange. The order enters the closing auction and fills at the single price that clears the maximum volume at 4:00 p.m. ET. MOC orders ensure a fill but surrender all price control — the execution price is whatever the auction clears at.
HOW IT WORKS¶
MOC orders are submitted during exchange-specific windows before the close. On the NYSE, the entry deadline is 3:45 p.m. ET and cancellations are blocked after 3:58 p.m. ET. On Nasdaq, the deadlines are 3:50 p.m. ET and 3:55 p.m. ET respectively. Orders submitted after the cutoff are rejected outright.
At 4:00 p.m. ET, the exchange aggregates all MOC orders alongside resting limit and market orders. The auction resolves at the price that crosses the maximum number of shares. Every MOC order fills at that single price — no bid-ask spread is paid. NYSE limits individual MOC orders to 500,000 shares or $2 million in value; larger orders require exchange approval.
Exchanges publish a closing imbalance indicator beginning at 3:30 p.m. ET showing whether buy or sell MOC interest dominates. A large buy imbalance typically pushes the auction price above the prevailing bid; a sell imbalance pushes it lower.
Key use cases include:
- Index funds and ETFs buying at the close to minimize tracking error against NAV
- Active traders exiting positions before overnight risk without relying on a limit fill
- Institutional desks reading the imbalance feed as a short-term directional signal
MOC orders differ from limit-on-close (LOC) orders. A LOC order sets a minimum acceptable price and may not fill if the auction clears worse than the limit. A MOC order always fills, regardless of price.
IN TAPEBOARD¶
Tapeboard surfaces the NYSE and Nasdaq closing imbalance feed in real time, updated throughout the 3:30–4:00 p.m. ET window. Traders can monitor net buy or sell imbalance by symbol directly in the terminal and set alerts when imbalance crosses a defined share or dollar threshold.
When reviewing a completed MOC fill, Tapeboard displays the official auction price alongside the last regular-session print, so traders can immediately measure auction slippage. Order entry deadlines for NYSE and Nasdaq are shown as a countdown timer on the order ticket when MOC is selected as the order type.