Regulated open banking in New Zealand officially started on Monday, the first step in a phased roll-out of open banking, under which customers' financial information will be shared by banks with third parties accredited by the Ministry of Business, Innovation and Employment, according to a statement by the country's Ministry of Commerce and Consumer Affairs.

New Zealand's Ministry of Business, Innovation, and Employment will provide regulatory oversight of the open banking regime, per the statement. Information sharing can only be done under the customer's explicit consent.

Four major banks, ANZ Group Holdings (ASX:ANZ, NZE:ANZ), Westpac Banking (ASX:WBC, NZE:WBC), Bank of New Zealand, and ASB Bank, which is owned by Commonwealth Bank of Australia (ASX:CBA), are required to have open banking systems in place by today, per regulations released in October. Other banks and deposit-takers can opt in voluntarily.

Kiwibank will be required to be ready by June 2026 for payments, and by December 2026 for other open banking services.

Shares of both ANZ Group Holdings and Heartland Group Holdings (ASX:HGH, NZE:HGH) fell over 1% in recent trading on the Australian bourse and almost 1% on the New Zealand bourse. Shares of Westpac Banking fell nearly 1% on both the Australian and New Zealand bourses.