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The Closing Single Price Auction (CSPA)

The CSPA is conducted after the completion of ASX’s continuous trading session at 4:00pm. Bids and offers are allowed to be entered, amended or cancelled in the order book during the pre-CSPA period up to 4:10pm. No overlapping bids or offers are matched during the pre-CSPA period.The closing auction’s matching algorithm, based on a series of rules (see below), operates at a random point between 4:10pm and 4:11pm. The algorithm’s primary purpose is to ensure the maximum amount of trades are settled at the most competitive level to produce the closing auction price.The auction algorithm uses four sequential decision rules to determine the auction price. If a clear result cannot be achieved when the first decision rule is applied, the model progresses to the next decision rule and so on.