Mitsui Life Insurance Co. and Asahi Mutual Life Insurance Co. will book roughly ¥100 billion each in securities evaluation losses for the nine months ended in December because of the higher yen and plunging stock markets, sources said Tuesday.

The two insurers will announce their financial results for the period, including their net losses, on Friday, the sources said.

Mitsui is taking sizable equity writedowns, while incurring greater expenses linked to mandatory reserves it is putting up to brace for the benefit payments it must make on the variable rate annuity policies it has sold, they said.

Asahi is booking losses on its foreign securities, which are susceptible to drops in foreign-exchange rates, and taking losses on its mutual fund holdings, they said.

Both insurers recapitalized late last year to improve their financial standings.

But they also are scrambling to improve their operations, including sales, to raise their profitability, the sources said.

The two may book net losses for the full year to March 31 unless share prices at home and overseas rebound, they said.

If Mitsui books a net loss for business 2008, it will be its second consecutive year in the red.