NEW YORK (Reuters) - MBIA Inc, the world's largest bond insurer, posted a quarterly loss of $2.4 billion yesterday as it took charges on billions of dollars of exposure to bonds linked to sub-prime mortgages.

But MBIA's beaten-down shares rose more than four percent as adjusted results beat expectations and the company said new business volumes appear to be rising from the first quarter.

MBIA is suffering as the US housing market deteriorates, lifting expected payouts on repackaged sub-prime mortgage bonds that the company insures.

The insurer expects the housing market to get worse before it gets better, but it has enough capital to withstand the market getting much worse.

US housing prices have dropped by more than 15 percent from their peaks in June by some measures and mortgage portfolios are performing much worse than expected.

"I don't know what's happening in the mortgage market and that's why we're taking a very cautious approach to the bond insurers," said Jim Ryan, an analyst at Morningstar in Chicago.

Earlier this year, the US stock market tumbled amid concerns the bond insurers would suffer big losses and be stripped of their top credit ratings.

Standard & Poor's and Moody's Investors Service affirmed the top ratings at MBIA's main insurance unit in February and although the agencies said the outlook for those ratings is negative, the market's concerns about bond insurers seem to have abated. Standard & Poor's said yesterday it was not taking any action on MBIA after the results.

The charges announced yesterday wiped out 40 percent of MBIA's net worth, but MBIA said most of the changes it recorded in the value of its exposure will not translate to actual payouts on insurance.

The first-quarter loss amounted to $13.03 per share, compared with a profit of $199 million, or $1.46 per share, in the same quarter last year.