A Bermudian-based specialist marine insurer has taken a major step towards merging with one of the world's leading protection and indemnity clubs, prompting AM Best to place its credit ratings under review while the transaction moves through the approval process.

Through Transport Mutual Insurance Association Ltd, the Bermuda parent of TT Club, and the United Kingdom Mutual Steam Ship Assurance Association Ltd, known as UK P&I Club, have signed a framework agreement committing to complete a merger on February 20, 2027, subject to regulatory and member approvals.

The announcement marks the next stage in a process first disclosed late last year, when the two mutual insurers confirmed they were exploring the deal.

The organisations also announced that their joint offer to acquire Thomas Miller Holdings, the management company that oversees both clubs as well as a number of other mutual insurers and specialist insurance businesses, is backed by a majority of the company's shareholders. The acquisition is expected to be completed during the fourth quarter of 2026, pending regulatory approval.

In response, ratings agency AM Best has placed the financial strength rating of A- (excellent) and the long-term Issuer Credit Rating of “a-” (excellent) of Through Transport Mutual Insurance Association Ltd and its subsidiaries under review with developing implications.

The ratings action does not reflect any deterioration in TT Club's financial position. Instead, AM Best said it would assess how the proposed merger and acquisition affect the group's balance sheet strength, operating performance, business profile and enterprise risk management before deciding whether the ratings should be affirmed, upgraded or downgraded.

The ratings will stay under review until the merger and acquisition are complete and the agency has evaluated the impact.

TT Club specialises in insurance and risk management for the international transport and logistics industry. The group's parent company is domiciled in Bermuda, while its insurance subsidiaries operate from the UK and the Netherlands.

The proposed transaction comes at a time when the global marine mutual insurance sector is seeing more consolidation. Notably, in 2023, the North of England P&I Club and Standard Club completed their merger to form NorthStandard, creating one of the world's largest marine insurers.

If approved, the merger would bring together two long-established marine mutual insurers while also bringing Thomas Miller, their longtime manager, under common ownership. The combined group is expected to begin operating in its new form in early 2027.

TT Club has been approached for comment on the transaction and whether it will have any implications for the group’s Bermuda operations.