Shares of MGIC Investment Corp. tumbled more than 20 percent Wednesday after the private-mortgage insurer posted a wider-than-expected fourth-quarter loss and said it can't predict when it will become profitable again.

The Milwaukee-based company reported a narrower fourth-quarter loss than it did a year earlier: $186.7 million, or 93 cents per share, compared with $280.1 million, or $2.25 per share, in the year-ago quarter.

Still, the latest quarter's loss was wider than the consensus estimate of analysts surveyed by FactSet, who expected a loss of 57 cents, on average.

Shares of MGIC dropped $2.39 to close at $9.26. The stock has traded in a 52-week range of $5.78 to $13.80.

For the full year, MGIC reported a loss of $363.7 million, or $2.06 per share, compared with a loss of $1.32 billion, or $10.65 per share, in 2009.

The earnings news release included a warning that the company doesn't see a return to profitability anytime soon: "We have reported net losses for the last four years, expect to continue to report annual net losses, and cannot assure you when we will return to profitability," the company said.