CHATTANOOGA, Tenn. – The fired president and chief executive of UnumProvident, the nation’s largest disability insurer, contends in a lawsuit that his $17 million severance and retirement package should be bigger.

J. Harold Chandler, who oversaw a $20-per-share drop in stock value during four years as the Chattanooga-based company’s top executive and left amid investigations of how it handled claims, wants another $3.4 million.

No hearing has been set on Chandler’s lawsuit, which was filed July 15 in Hamilton County Chancery Court.

UnumProvident, created by the 1999 merger of the Unum Corp. of Portland, Maine, and The Provident Cos., based in Chattanooga, claims about 30 percent of the nation’s disability insurance business.

The suit contends the company promised Chandler the same $20.4 million termination benefit it gave the former chairman and chief executive officer of Unum Corp. in 1999.

Chandler’s attorney, William H. Horton of Chattanooga, declined to comment Wednesday about the suit.