The Mather Group (TMG), a fee-only wealth management firm in Chicago, has acquired a multifamily office with more than $1 billion in assets under management as part of the launch of a new family office unit.

The acquisition of Astraeus Advisers in Park Ridge, Ill., marks the launch of a new division of Mather that has been named TMG Family Office, according to a Tuesday press release.

This follows TMG’s purchase about three months ago of Berman Investment Advisors, a San Francisco-based multifamily office with $1 billion in AUM. Berman and Astraeus have been combined to form the new family office unit, according to the press release.

“Acquiring Berman Investment Advisors and Astraeus Advisers, two well-respected multifamily offices, has allowed us to build TMG Family Office on a proven, strong foundation," TMG founding partner Stewart Mather said in a prepared statement. "The two firms have been working with families of significant wealth for decades and will bring invaluable experience to this new business unit.”

TMG Family Office serves 18 families with more than $5 billion in collective assets under advisement, the press release said. The new unit's services include financial planning, tax advisory and investment management, as well as concierge and lifestyle services such as basic bill payment and private aircraft management.

Mather, which also has offices in Houston, Dallas, Atlanta and the San Francisco area, was founded in 2011 and serves affluent and ultra-affluent families and individuals. It has 60 employees and more than $7 billion in assets under advisement.