(Adds details on outlook)
May 2 (Reuters) - Genworth Mortgage Insurance Australia GMA.AX posted a 71 percent slump in first-quarter underlying profit on Wednesday, and said it would buy back up to A$100 million ($75 million) of its shares.
Australia's largest mortgage insurer said the buyback would be subject to shareholder approval at the annual general meeting scheduled for May 10.
The company recorded a quarterly underlying net profit after tax of A$19.9 million, down from A$68.3 million posted a year ago when it realised a gain on rebalancing its investments.
The reported loss ratio, the percentage of premiums spent on claims, jumped 21.1 percentage points to 55.9 percent in the first quarter.
The firm left its full year guidance unchanged, saying that it continues to target a dividend payout in the range of 50 percent to 80 percent of underlying profit. ($1 = 1.3353 Australian dollars)