UPDATE 1-IAG cuts insurance margin f'cast on storm claims

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SYDNEY, Dec 19 (Reuters) - Insurance Australia Group Ltd (IAG.AX) (IAG), Australia's biggest home and car insurer, cut its insurance margin forecast for fiscal 2008 to 9-11 percent from 11-13 percent due to storm damage claims, sending its shares down.

IAG said it had received about 21,000 claims from storms which lashed New South Wales state earlier in December, with an expected impact of A$105 million ($90.5 million).

This is the third event in less than two years which has resulted in total claim costs exceeding A$100 million.

IAG Chief Executive Michael Hawker said about 60 percent of the claims were from hail-damaged cars. He said Sydney was experiencing the wettest year since 1998, which has increased the frequency of claims within IAG's major portfolios.

Other insurers are yet to give details about the financial impact from the storm, though Suncorp Metway Ltd (SUN.AX) said it had received about 17,500 claims by Monday.

In October, IAG lowered its gross written premium growth estimates for the current fiscal year due to difficult conditions in the UK car insurance market.

IAG is Australia worst performing major financial stock this year, having fallen about 34 percent compared with a 10 percent rise in the benchmark S&P/ASX 200 index .AXJO.

Shares in IAG lost as much as 3.6 percent in early trade, and by 2309 GMT were off 2.9 percent at A$4.08. ($1=A$1.16) (Reporting by Denny Thomas; Editing by James Thornhill)