The 601 Tower at Carlson Center in Minnetonka has found a buyer.

Newport Beach, California-based KBS Real Estate Investment Trust II, Inc., will purchase the building for more than $54.4 million.

According to a U.S. Securities and Exchange Commission (SEC) filing, KBS entered into an agreement last week to buy the 15-story building for $54.4 million plus closing costs.

The tower-which has an estimated market value of $42 million, according to Hennepin County tax records-was put on the market in August by its owner, New York-based Teachers Insurance and Annuity Association of America-College Retirement Equities Fund.

The building did not have an asking price when it was put listed by Minneapolis-based C.B. Richard Ellis.

According to the SEC filing, the office building has 288,458 rentable square feet and is on about 2.3 acres. It is currently 90 percent leased to 43 tenants-including HQ Global, RBC Capital Markets, Conopco, Inc., and Wachovia Securities.

The 601 Tower, better known as one of the “Carlson Towers,” features a two-story polished marble atrium capped with a 55-foot rotunda, with an exterior of reflective glass and polished burgundy granite. It was built in 1989.

The 601 Tower's twin tower-the 701 Tower-wasn't put up for sale. It is owned by Carlson Real Estate Company and houses the headquarters of Carlson, one of Minnesota's three-largest private companies.