Investors ploughed into the ASX-listed shares of Genworth Mortgage yesterday after the company declared a bumper special dividend.The country's largest LMI provider reported a bottom line of A$88.1 million for the six months to the end of June - up from $41.9 million in the corresponding period last year.While the latest half year result was inflated by a $45 million unrealised investment gain, investors were buoyed by a surge in new insurance written, which rose by almost 21 per cent to $12.5 billion.The unfranked special dividend of 29 cents per share surprised shareholders who will also receive a fully franked ordinary half year dividend of nine cents.Genworth has partly funded the special dividend with capital funds that were originally intended to be used to support its latest share buyback.The buyback was recently terminated with $36 million of surplus funds.Chief executive Georgette Nicholas announced the launch of a new LMI product that allows borrowers to pay insurance premiums in monthly instalments rather than as a single upfront payment."It provides borrowers with the option of not capitalising the premium into the loan, as many do today, or paying the entire LMI premium upfront. Instead, they can pay the LMI premium in instalments over time," she said."This means a greater portion of their loan can be utilised to support the purchase of the property. "Importantly, our new monthly premium LMI provides borrowers with the flexibility to refinance at a later date - without the need for a refund of LMI premium - and lenders with the option of structuring this offering to enable borrowers to cease paying the LMI premium when their loan achieves a certain LVR." Genworth's share price closed up 44 cents or 15 per cent to $3.39.