BMO Financial Group is parting with its U.S. retirement services business.

The bank holding company will sell BMO Retirement Services, a division of BMO Global Asset Management, to mutual insurance company OneAmerica, the company announced in a press release last week.

The sale of the unit supports BMO's strategy to focus on its asset management business, according to Barry McInerney, co-CEO of BMO Global Asset Management. "The transaction will not change BMO's role in managing a portion of the investments in the plans moving over to OneAmerica as well as acting as the directed trustee and custodian of those plans," he said in the release.

BMO Retirement Services, which has more than 200 professionals with approximately 830 plans, will adopt the name OneAmerica Retirement Services. It will continue to operate from BMO's current locations and most clients will continue to work with their current service teams, according to the announcement.

"The addition of this business expands our award-winning service platform, enriches our professional services individually directed account capability and gives us additional sales expertise and geographic reach," Bill Yoerger, president of the retirement services division for OneAmerica, said in a statement.

The retirement services businesses of OneAmerica serve more than 11,000  plans and have more than $30 billion in assets under administration.  The acquisition will boost OneAmerica's assets under administration by approximately $26 billion, according to OneAmerica.

"Adding BMO's retirement services business enhances our already strong position as a leader in the retirement services industry and complements our high-touch, relationship-based service model," said Scott Davison, president and CEO of OneAmerica.

The transaction is expected to close during the third quarter of 2015. Terms of the agreement were not disclosed.

Read More: