A deal that helped AIG repay US taxpayers last week may come at MetLife shareholders' expense, or so at least JP Morgan, itself a beneficiary of Treasury largess, contends.

In fact, a JP Morgan research note published on Monday contends that MetLife may have overpaid for its $15.5 billion acquisition of Alico, an American International Group's life insurance unit, and that could endanger the company's credit ratings.

Although the transaction will bring MetLife into foreign markets, especially Japan, JP Morgan analysts believe the company is overpaying, they wrote Monday.

They calculate that the transaction values Alico at over 10 times earnings and above 1.2 times book value. And while they say these multiples seem reasonable, they note they are considerably higher than the sector's current valuation of 8 times 2011 earnings per share and 0.9 time book value.

If nothing else, the analysts say, MetLife's credit profile is likely to suffer. "Based on recent ratings agency commentary, it is possible that MetLife could be downgraded by one or more agencies," JP Morgan continued.

While Fitch Rating has already and affirmed MetLife's A rating based on long-term financial and strategic benefits of the acquisition, other agencies think differently.

Moody's Investors Service affirmed the company's rating, but changed its outlook from stable to negative. Standard & Poor's put MetLife's ratings on watch with negative implications last month and kept the credit watch today. It also said it would likely lower its rating by one notch once the acquisition closes, as the announced transaction would result in capitalization below its expectations for the rating.