On This Page
Key Takeaways
- The listing exchange’s closing auction combines eligible orders to establish its official closing price.
- Market-on-close orders target the auction price; limit-on-close orders add a price boundary.
- Read indicative price, paired quantity and imbalance together.
- At the worked $88.40 candidate price, 420,000 buy shares pair with 420,000 sell shares, leaving 90,000 sell shares.
- Compare the final auction with closing volume, the day’s price action and options activity.
What is a closing auction?
A closing auction is a single-price match of eligible buy and sell orders at the end of regular trading. The listing exchange uses its auction to establish the official closing price, a benchmark for funds, indexes, valuations and trading performance. Market-on-close orders target that auction price, limit-on-close orders add a price boundary, and other eligible orders join under the venue’s matching rules.
How to read a closing auction imbalance
At each candidate price, compare eligible buying with eligible selling. The smaller quantity sets paired size. The difference identifies the unmatched side and quantity.
The worked snapshot has 420,000 eligible buys and 510,000 eligible sells at $88.40. It pairs 420,000 shares, worth $37,128,000, and leaves 90,000 shares of sell imbalance.
New orders and changes in candidate price update those quantities. A $50 buy LOC is price-eligible at $50 or below and drops out above $50. Track the fields together as the auction develops.
Formula
Closing matched quantity at a candidate price = min(eligible buy quantity, eligible sell quantity)- The official price follows the listing exchange’s auction algorithm, collars, and tie breakers.
- Unmatched quantity equals the absolute difference between eligible buy and sell interest at the measured price.
Worked Example
At an indicative closing price of $88.40, the auction contains 420,000 eligible buy shares and 510,000 eligible sell shares.
- Paired quantity: min(420,000, 510,000) = 420,000 shares
- Sell imbalance: 510,000 − 420,000 = 90,000 shares
- Matched notional: 420,000 × $88.40 = $37,128,000
At the $88.40 candidate price, 420,000 shares pair for $37,128,000 of matched value, leaving a 90,000-share sell imbalance. Track the next auction update to see how added orders and price eligibility change the match.
Closing auction times at Nasdaq and NYSE
Use the listing exchange’s calendar and order deadlines. On a standard session, Nasdaq starts closing-imbalance dissemination at 3:50 p.m. Eastern. NYSE's MOC and LOC entry cutoff is also 3:50 p.m., with specified offsetting orders accepted afterward. NYSE begins its closing-auction process at 4:00 p.m.
The exchange applies its price-selection rules, collars and tie breakers, then executes paired orders at the selected price. Use the official closing-price field when benchmarking the result.
How traders use the closing auction
Compare auction size with the stock's usual closing volume and the full session. Identify how the final price relates to the day’s range and the levels in your plan.
Carry the closing level into the next session’s plan as a precise price reference. Options flow shows the ticker’s contract activity by strike and expiration, and the options profit calculator compares entry cost and payoff for a structure at your target prices.
Limitations of the closing auction
- Track each update until the auction executes. Indicative price, paired quantity and imbalance are snapshots that new orders and changes in candidate price keep moving, so the final price can differ from any earlier update.
- Read an imbalance as unmatched interest at one candidate price. Benchmark tracking, rebalances, portfolio transitions and hedge adjustments all feed the close, so the imbalance carries no single motive.
- Use the listing exchange’s rules. Times, entry cutoffs, collars and tie breakers follow each venue’s rules, and the 3:50 p.m. times above apply to a standard session.
- Choose the order type for the risk you accept. A market-on-close order has no price boundary and accepts the auction price; a limit-on-close order can go unfilled when the auction prices beyond its limit.
- Track after-hours trades separately. The official close does not include them, so the next session can open away from it.
Bottom line
The closing auction matches eligible orders at one price to set the official close that funds, indexes and performance measures rely on. Read its indicative price, paired quantity and imbalance together as the auction develops, use the listing exchange’s official closing-price field as the benchmark, and track after-hours trades separately.
Clear answers
Frequently Asked Questions
Sources and Further Reading
How entries are sourced, calculated and updated: editorial methodology.