Terms of the deal are not being disclosed, said Franklin Templeton spokeswoman Rebecca Radosevich.
Athena Capital, which has about $6 billion in assets under management, provides impact investing and outsourced chief investment officer services for both tax-exempt institutions and family offices.
Ms. Radosevich said Athena Capital's services will be under the Fiduciary Trust brand at some point in the future. The deal is expected to close in the second quarter, a news release said.
Athena Capital is privately owned. The firm was founded in 1993 by Lisette Cooper, the firm's managing partner and chief investment officer. Any changes in titles or personnel have yet to be determined, Ms. Radosevich said.
Fiduciary Trust Co. International has $75 billion in AUM and is a wholly owned subsidiary of Franklin Templeton, which has $691 billion in AUM.