The sale of two arms of its operation is set to boost the undeployed capital at White Mountains Insurance Group to $2.5 billion.

Bermuda-domiciled financial services group Symetra has been bought over by Sumitomo Life Insurance of Japan, while reinsurance firm Sirius has been sold to CM International (CMI) the Singapore-based arm of China Minsheng Investment Corporation.

White Mountains chairman and chief executive Ray Barrette said: “It was a big quarter, driven by the agreements to sell Sirius Group and Symetra.”

The news came in the third quarter financial report for White Mountains, released yesterday.

The firm also reported adjusted comprehensive loss of $77 million in the third quarter, compared to $13 million for the same quarter last year.

Net loss attributable to common shareholders was $59 million, compared to net income of $51 million in the same period of 2014.

The report said White Mountains had repurchased and retired 215,540 of its common shares at an average price of $738.51, a total of $159 million, in the third quarter of this year.

It added that White Mountains had received a special dividend of 50 cents per share in Symetra in the third quarter and expected to get $32 per share in cash when the deal with China Minsheng Investment closes in the first quarter of next year.

The report said that Sirius third-quarter included losses of an estimated $15 million from the massive explosion in the Chinese port of Tianjin in August.

Allan Waters, chairman of Sirius, said: “In the third quarter we experienced an unusually high amount of non-catastrophe large loss occurrences, including the Tianjin loss.

“Excluding currency effects, Sirius Group’s adjusted book value per share grew three per cent over the first nine months.

“The CMI transaction was announced on July 27 and we continue to work towards regulatory approvals. We still anticipate the transaction to close in the first quarter of 2016.”