CNOOC Limited filed its Monthly Return with Hong Kong Exchanges and Clearing Limited for the period ended 31 March 2026, indicating no movements in either Hong Kong-listed or Shanghai-listed share classes.

• Issued share capital remained unchanged at 44.54 billion ordinary shares listed in Hong Kong and 2.99 billion RMB-denominated shares listed in Shanghai; the company held no treasury shares in either market.

• CNOOC confirmed that it satisfied the applicable public-float threshold—5 percent of total issued shares for PRC issuers with dual listings—as of the month-end close.

• No share options, warrants, convertible securities, or other arrangements affecting the share count were reported for the month.

The return, signed by Joint Company Secretary Xu Yugao on 1 April 2026, fulfills Main Board Rule 13.25C disclosure requirements.