Tokio Marine Holdings Inc., Japan’s largest insurer by market value, is withdrawing from the Net Zero Insurance Alliance, the latest in a wave of defections from the world’s biggest climate alliance for insurers.

The company declined to give a reason for its withdrawal. A spokesperson said Tokio Marine will continue to consider measures to realize a decarbonized society such as the use of renewable energy and emphasized it will keep a close eye on social and environmental causes.

Allianz SE, Axa SA and Lloyd’s of London left the NZIA last week, following earlier defections by several founding members including Munich Re. The alliance is a sub-group of the Glasgow Financial Alliance for Net Zero, known as GFANZ, a coalition of global financial institutions “committed to accelerating the decarbonization of the economy.”

MS&AD Insurance Group Holdings Inc. announced on Monday it has withdrawn from the NZIA and pledged to continue with its plan to reach net zero emissions by 2050. Japan’s Sompo Holdings Inc. also quit the group last week.

Insurance companies have been explicitly targeted by the US Republican Party’s escalating anti-ESG campaign, and the mass defections have posed an existential question for NZIA. Convened by the United Nations Environment Programme in 2021, the group at its peak represented about 15% of global insurance premiums.

The political attacks are interfering with insurers’ independent efforts to price climate risk, which will harm policyholders, main street investors and local economies, a GFANZ spokesperson told Bloomberg last week.

Michael R. Bloomberg, the founder of Bloomberg News parent Bloomberg LP, is co-chair of GFANZ together with former Bank of England Governor Mark Carney.

--With assistance from James Poole, Jason Scott and Alastair Marsh.

(Updates with MS&AD and Lloyd’s departures in third and fourth paragrahs.)