CHATTANOOGA, Tenn. – UnumProvident, the nation’s largest disability insurer, will pay a $15 million fine and reconsider about 200,000 denied claims in response to a multistate investigation, company executives said Thursday.

Including the penalty, a proposed agreement with insurance regulators in all 50 states would change claims handling and other operations at a total before-tax cost of $127 million in the fourth quarter, a spokeswoman said.

Insurance regulators in Tennessee, Maine and Massachusetts, the lead states in the investigation, signed the agreement, as did officials in New York and the U.S. Department of Labor, spokeswoman Mary Clarke Guenther said.

In trading Thursday on the New York Stock Exchange, UnumProvident shares fell 36 cents to close at $13.73.

The company insures more than 25 million people and has about a quarter of the disability insurance market.

Paula Flowers, commissioner of the Tennessee Department of Commerce and Insurance, said that while problems were noted in a very small percentage of claims there were enough that “corrective action was warranted.”