Marcus Merz is retiring as chief executive at PreferredOne, the Golden Valley-based health insurer that offered rock-bottom premiums on the MNsure exchange before announcing this fall it would exit the government-run marketplace.

Merz has been CEO at the company since 1984 and will continue in the job until year's end, according to a prepared statement released by PreferredOne on Monday. He will be replaced by interim-president Paul Geiwitz, who is currently the company's chief marketing officer.

Merz turned 67 in May and said in an interview he's retiring for personal reasons. It's not driven, he said, by the company's troubles this year in the "individual" market, where individuals buy non-group coverage for themselves and immediate family members.

"I'd pretty much made my decision when I turned 67," Merz said. "You want to have some time to get off the train, and do something different."

During the first year of Minnesota's health insurance exchange, PreferredOne sold individual market coverage at premiums that in many categories were the lowest in the nation. Rates in the Twin Cities were particularly low, and the company won about 60 percent of the business through MNsure, as a result.

But in September, PreferredOne announced it would not return to the marketplace in 2015, saying its business through the exchange was "not sustainable." The company is increasing individual market premiums next year by an average of 63 percent.

During the first three quarters of 2014, the company had incurred $1.40 in claims for every dollar of premium revenue in the individual market, according to a regulatory filing in November. The individual market includes both policies sold through MNsure, and those sold directly by health insurers.

Beyond the individual market, PreferredOne sells health insurance to small and large employer groups and serves as a third-party administrator for large companies that "self-insure" against medical costs. More than 2,000 groups have insurance or administrative services from PreferredOne, the company said in its statement.

"During his tenure, Marcus has made significant contributions to the organization's success," said board chairman Dan Fromm. "The board thanks Marcus for his leadership over the past years."

The company did not make Fromm available for an interview.

PreferredOne is owned by Minneapolis-based Fairview Health Services, Robbinsdale-based North Memorial Health Care and a physicians group.

Christopher Snowbeck • 612-673-4744

Twitter: @chrissnowbeck