ASX update to Open/Close

ASX has made a number of changes to its Operating Rules that are scheduled to come into effective on 23 June 2025. These include:  

Block and Late Trade reporting simplification – Procedure 3500

ASX currently requires that block trades are reported using different trade report codes depending on which tier the instrument is allocated e.g. S1, S2 and S3. In order to simplify the reporting of block trades for equity market products, CGS depository interests and ETFs, these trades will now be reportable to the ASX under a single code ‘SC’. ASX will continue to validate the notional value of the trade and reject the trade if required.

Facilitated Special Size Block Special Crossings (FSSBSC) (to be known as Large Principal Transactions (FSSBSC)) will also utilise the ‘SC’ trade report code.

Late Trading

ASX will be consolidating Late Trade reporting codes to LT and L5 which will help reduce complexity for participants entering these trade reports.

Removal of Open Stagger/ New Opening Single Price Auction (OSPA) Session State

ASX is introducing a new Opening Single Price Auction (OSPA) Session State to enable the orderly consumption of the burst of messages during the single opening auction.

ASX has published a video that explains this in detail: https://www.asx.com.au/markets/trade-our-cash-market/equity-market-working-group

Post Close Session State

ASX is introducing a new Post Close Session State.

ASX has published a video that explains this in detail: https://www.asx.com.au/markets/trade-our-cash-market/equity-market-working-group

Miscellaneous Changes

A number of miscellaneous changes have been made to Procedures including an update to Fair and Orderly Markets to ensure that Authorised Signatories of Participants are available to receive communications from the commencement of the OSPA Session State through to the completion of the Post Close Session State.