Progressive Corp. (PGR) returned to the black in the third quarter after being hurt last year by $1.37 billion of investment losses.

The auto and home insurance company said claims costs were also lower, as earnings handily topped analysts' expectations. Shares rose 5.8% premarket to $17.40.

The results come as insurers have been battling for market share amid an ever-competitive environment in which consumers are more interested in price comparisons.

Progressive's earnings were $269.9 million, or 40 cents a share, compared with a year-earlier loss of $684.2 million, or $1.03 a share. Net premiums written rose 1.2% to $3.55 billion.

The mean estimates of analysts surveyed by Thomson Reuters were earnings of 33 cents and net premiums written of $3.56 billion.

The combined ratio, a measure of premiums received to claims paid, fell to 92.7% from 95.1%.

The number of auto policies in effect was up 4.6% at 7.4 million while other consumer policies, mainly homeowners, climbed 2.7% to 3.5 million.

-By Kevin Kingsbury; Dow Jones Newswires; 212-416-2354; kevin.kingsbury@dowjones.com