UPDATED DATE: New Delta Adjusted at Close fields in OPRA Flex messages Opra Notice <opra-notice@opraplan.com> 9:59 AM (1 hour ago) to Opra, OPRA July 16, 2020 To: OPRA Multicast Subscribers Subject: UPDATED DATE: New Delta Adjusted at Close fields in OPRA Flex messages What You Need To Know New Last Sale Delta on Close Flex messages will be reported to OPRA. Delta Adjusted at Close Message Description: A Delta Adjusted at Close (DAC) trade will include delta per leg and an underlying reference price. The execution will take place during the regular trading hours and be adjusted by multiplying the delta by the difference between the underlying reference price and the official closing price of the underlying. An initial matched trade will be sent to the OCC and a last sale to OPRA upon the initial execution. Upon receipt of the official closing price of the underlying, the execution price will be restated. Upon restatement, a delete for the original matched trade and a new matched trade add will be sent to the OCC. A new report will be sent to OPRA in text format. Changes Being Made Participants can report information in additional fields in the Administrative message (Category C, Type=space filled), denoting new Delta at Close pricing in Last Sale Equity and Index Flex messages. The new fields are as follows: Delta Adjusted at Close (Initial): Price Type: DAC Delta: .50 Reference Price: 3345.75 Delta Adjusted at Close (Adjusted): Price Type: DAC Delta: .50 Reference Price: 3345.75 Closing Price: 3351.25 OPRA specifications have been revised to include the new fields in Flex message samples. When will it take effect? OPRA will disseminate the new Flex message fields as early as Monday, September 14, 2020.