Standard & Poor’s has upgraded Swiss-based insurer Ace Group’s counterparty credit rating from A to A+.

In a research update the ratings agency praises Ace’s “strong balance sheet and track record of superior operating performance”.

It has also raised its counterparty credit and financial strength ratings on Ace’s core operating companies in North America, Europe and Bermuda from AA- to AA, while the “highly strategically important subsidiaries” that include Australia and New Zealand move from A+ to AA-. The outlook on all of these companies is “stable”.

S&P expects Ace “will maintain [its] extremely strong capital and competitive position, supported by consistent and stable operating performance”.

The update notes Ace’s “very strong” profits in the five years to last year, with a combined operating ratio of 91%, a return on revenue of 21%, and 12% return on equity.

“Ace’s diversified platform has contributed to the group’s lower earnings volatility than many of its peers in recent years,” S&P says.

There is one caveat in the otherwise glowing report: “We could take negative rating actions over the next 24 months if the group is unable to maintain its historical levels of superior underwriting profitability or if capitalisation erodes.”