Massachusetts Mutual Life Insurance Company says it now owns all of the stock of Winmark Equipment Finance L.L.C., a large, 3-year-old equipment-leasing finance company.

MassMutual, Springfield, Mass., founded Winmark, Foxborough, Mass., with CrossHarbor Capital Partners L.L.C., Boston, in 2004, and the company now has 150 customers and $725 million in assets under management, according to MassMutual.

MassMutual and CrossHarbor each started with half of Winmark’s stock.

MassMutual is not saying how much it has paid CrossHarbor for CrossHarbor’s share of the company, but MassMutual says it will keep Winmark’s management team and change the name of the company to MassMutual Asset Finance.

MassMutual will be providing the resources to help Winmark expand its operations to enter the dealer floorplan, federal leasing and corporate aircraft finance markets, according to Winmark executives.

Winmark has been focusing mainly on arranging transactions with a value of $5 million to $25 million for investment-grade public companies and private companies with good credit profiles.