Unum headquarters in downtown Chattanooga.

Unum Group beat Wall Street estimates by three cents per share in the second quarter, posting after-tax income of $232 million, or 75 cents per share.

The Chattanooga-based disability insurer exceeded second quarter 2010 results by $3.4 million, when the company posted after-tax income of $228.6 million, or 69 cents per share.

Earnings per share were bolstered by a $1 billion share buyback program the company announced in February, said Tom Watjen, president and CEO of Unum.

"We benefited from solid operating and investment performance as well as the share repurchases we began last year," Watjen said. "We also continued to see modest growth in most of our target markets, primarily within our U.S. businesses."

Of Unum's three primary segments, Unum US posted quarterly operating income of $218.1 million, up $2.1 million, or 1 percent, from the second quarter of 2010.

Unum UK grew operating income to $54.7 million, a 3.4 percent increase over the $52.9 million that the division earned in the second quarter of 2010.

The company's Colonial Life segment saw income grow 1.8 percent from the second quarter of 2010 to $75.2 million, up from 73.9 million.

Growth was modest as the slow economy continues to hold back customer growth, with sustained high levels of unemployment, Watjen said.

Unum reported its quarterly results after the company's stock dropped 2.6 percent, or 63 cents per share, to close Tuesday at $23.59 -- its lowest price since December.

"Although the economy and current employment trends continue to challenge our top-line growth, our disciplined approach to the business is serving us well," Watjen said.

The company will continue to seek growth, but in a "disciplined, responsible way," Watjen said.