Bermuda’s role as a strategic reinsurance hub for major global insurers received another boost after AM Best upgraded the issuer credit rating of MS Amlin AG, now operating as MS Reinsurance, citing its growing importance to Japanese insurance giant Mitsui Sumitomo Insurance Co.

The ratings agency upgraded the company’s Long-Term Issuer Credit Rating to “aa” from “aa-” and affirmed its Financial Strength Rating of A+.

AM Best said the upgrade reflected the assignment of “full rating enhancement” from parent company MSI, pointing to the reinsurer’s increasing strategic and financial importance within the wider MS&AD Insurance Group.

“The company, with its operating hubs in Zurich, Bermuda and the United States, is a key platform for MS&AD’s strategy to increase its exposure to international markets and differentiate its premium and profit base geographically,” AM Best said.

The agency added that MS Re now accounts for a major share of the group’s international premiums and profits, writing approximately $4 billion in gross premiums in 2025.

AM Best pointed to the explicit support provided by MSI, including a full unconditional parental guarantee.

MS Re has steadily consolidated the group’s international reinsurance operations in recent years. The company previously absorbed Bermudian-based MS Frontier Re Ltd as part of a broader restructuring to streamline the group’s global platform.

The reinsurer recently rebranded from MS Amlin to MS Re.