Allstate Corp.’s shares tumbled in late trading after the insurer’s third-quarter profit missed analyst estimates.

Operating earnings of $452 million, or 83 cents a share, were down 16 percent from the same period a year earlier as Allstate’s homeowners unit reported an underwriting loss on costs tied to settling a class-action lawsuit. Analysts surveyed by Thomson Reuters had expected an operating profit of 98 cents a share.

The stock fell 4.7 percent to $30.95 in after-hours trading. Results were released after markets closed on Wednesday.

The class-action case had alleged that Allstate had failed to properly pay general contractors who oversaw construction work on its customers’ damaged homes. While the case hasn’t yet formally settled, Allstate’s settlement offer “appears acceptable to the plaintiffs,” which prompted the company to set aside $70 million in its reserves, the firm said in a regulatory filing.

The company’s auto-insurance operation, its largest unit, also reported less favorable results. Underwriting income fell 8.8 percent to $281 million as a decrease in claims costs failed to offset a decline in premium revenue. The company continued to lose auto policyholders, as new customers were outnumbered by those who dropped coverage for the 11th straight quarter.

Reversing the decline in auto policyholders has become one of Chief Executive Officer Tom Wilson’s main goals at Allstate. The company has tied its employee-incentive programs to customer loyalty and increased its spending on advertising in an effort to boost its policy count.

“We have to get to higher customer-service standards,” Wilson said in an interview. “We’ve been pushing that hard. We did not make progress on that in this quarter” based on the company’s own measures of loyalty.

But the auto results were also affected by price increases in Florida and California that caused some customers to leave when their policies were due to renew, Wilson said.

While analysts most closely follow operating results, the company’s net income, which includes investment gains and losses, surged 66% to $367 million on markedly improved investment results.

Furthermore, the company said it expects to hit its 2010 target of a 10- to 12-cent profit margin for every dollar it collects in premiums from its home and auto customers. That figure excludes catastrophe costs and the sort of reserve reestimate that cost the homeowners unit money in the third quarter.

On that basis, the company earned 10.8 cents on every dollar after paying claims and expenses in the quarter.