By Joseph A. Giannone

NEW YORK (Reuters) - MetLife Inc (MET.N: Quote, Profile, Research) executives on Thursday told investors the subprime mortgage crisis has inflicted minimal damage to its portfolio of investments and loans, and that the insurance giant remains comfortable with its exposure to mortgage markets and bond insurers.

Subprime mortgages, or home loans extended to the riskiest borrowers, represent less than 1 percent of the insurer's $345 billion portfolio, or $2.2 billion at the end of 2007, the company said in a conference call. There were no write-downs and less than $1 million of realized losses during the fourth quarter.

"We remain comfortable with both the amount and quality of our subprime residential mortgage-backed securities," said Steven Kandarian, MetLife's chief investment officer, in the call to discuss fourth-quarter results reported on Wednesday.

Shares of MetLife rose $1.74, or 3.1 percent, to $58.09 in morning trading on the New York Stock Exchange. The shares are down 14 percent over the past three months.

Total unrealized losses at MetLife increased to $222 million during the quarter, due to widening interest-rate spreads.

MetLife also assured investors that the quality of its holdings were high: 97 percent of its mortgage holdings are rated triple-A or double-A, while the remaining holdings come from earlier vintages when underwriting was stronger.

Kandarian disclosed that its holdings of collateralized debt obligations (CDOs) backed by subprime mortgages were "very small." Paper losses on its subprime CDOs were $15 million at the end of December.

TROUBLING TRENDS