An investment group led by retired Best Buy founder Richard Schulze has purchased a 25 percent stake in Meristem Family Wealth, the Minnetonka-based firm that provides investment-and-trust services to more than 150 affluent families.

Meristem, which manages about $2.35 billion in assets, will invest the unspecified capital infusion in expansion of its Naples, Fla., and Scottsdale, Az., offices, its South Dakota-based trust company and people and technology, said Meristem CEO Charlie Maxwell.

"We only serve individuals and families and we're an independent fiduciary," said Maxwell, who owns the 16-year-old firm with four other employees. "We've got a track record of steady growth. And we also wanted to create opportunity for the 40 men and women we have in the firm."

Meristem is a local pioneer in the growing business of "multi-family" offices. In 2004, Sargent Management, formed in 1961 to manage the affairs of the Pillsbury family that founded the flour-and-food company now part of General Mills, merged into the predecessor of Meristem.

The trend is driven by wealthy, extended families with assets of several million to hundreds of millions, who want one-stop assistance in everything from choosing investment managers to financial planning, estate and tax help. Family offices may assist with financial education for children and help establish philanthropic plans.

Multi-family offices also can operate more efficiently and spread costs across a broader base, allowing affluent families to often pay less than 1 percent of assets annually for services.

They compete largely with bank trust-and-wealth management departments.

"We believe Meristem has a strong platform…focused people and clear purpose," Schulze said in a prepared statement. "We are excited about the opportunity to help them extend these qualities to new clients and contribute to their growth. We share many of the same financial and philanthropic values."

Schulze's investment group includes Kevin Bergman, chief operating officer of Olympic Ventures, the Schulze family office based in Minneapolis; and Naples wealth consultant Michael Benson.

Schulze, 75, through his Richard M. Schulze Family Foundation, also has become one of Minnesota's big philanthropists. He has pledged to donate $1 billion of his accumulated wealth to charitable causes.