PORTLAND – Colin Hampton, the former Unum Corp. CEO who orchestrated the disability insurer’s groundbreaking switch in 1986 from mutual ownership to a stock company, has died at age 79.

Hampton died July 24 in Amelia Island, Fla., after heart surgery.

From the time he became CEO in 1970 until his retirement in 1988, Unum’s assets grew from $270 million to more than $7 billion.

Hampton joined Union Mutual Life Insurance Co. in 1956 as a security analyst. He quickly advanced in the company and became CEO and chairman of the board in 1970.

Under his tenure the company gained a reputation as the leading seller of long-term disability income and the only insurance company with a dominant position in both group and individual disability income.

The company changed its name to Unum during the 1986 demutualization, which sparked an industrywide trend. Many other large insurers have since gone public, including Equitable Cos., John Hancock, Met Life and Prudential.

After Unum became listed on the New York Stock Exchange, its surplus was distributed to policyholders in cash and stock totaling roughly $652 million.

During his 18-year tenure, the insurer’s annual profits grew from $2.5 million to more than $125 million.

A New Haven, Conn., native, Hampton graduated from Vanderbilt University. He served in the Air Force during World War II.

In 1951, he married Marjorie Alice Brown of Savannah, Ga.

He was active in civic organizations and served on the board of several large companies and nonprofit institutions in Maine.

More than a decade after Hampton’s retirement, Unum merged in 1999 with insurer The Provident Cos. UnumProvident Corp. is now based in Chattanooga, Tenn.

Hampton is survived by his wife; his son Colin Hampton Jr. of Sea Ranch Lakes, Fla.; his daughter Carolyn Hampton LoRusso of Medfield, Mass.; and four grandchildren.