Global asset management company Affiliated Managers Group (AMG) announced today the acquisition of pure play ESG fund manager Parnassus Investments.

Launched in 1984, Parnassus was a pioneer in active responsible investing, with each of its equity and fixed income strategies using ESG criteria. The firm’s investment approach aims to invest in companies that build wealth for clients, while having a positive impact on society. According to AMG, Parnassus is the largest pure-play ESG mutual fund company in the U.S., with approximately $47 billion assets under management (AUM).

Following the acquisition, Parnassus partners will continue to own a substantial portion of the equity of the firm, and the investment team will remain fully independent. AMG employs a partnership approach, aimed at preserving  the operating and investment independence of its Affiliates, while providing benefits including global distribution.

Benjamin E. Allen, Chief Executive Officer of Parnassus, said:

“Since our founding, we have been committed to remaining independent and investing based on both Principles and Performance. AMG’s unique partnership approach preserves our firm’s entrepreneurial and investment-centric culture, which is essential to our clients and team; the cultural alignment between Parnassus and AMG, with our firms’ respective long-term partnership orientations and strong shared belief in sustainable investing, made our decision clear.”

The acquisition follows an agreement earlier this year to acquire a stake in Boston Common Asset Management, a women-owned and led global equity manager dedicated to integrated ESG impact investing. The Parnassus transaction marks a significant step forward for AMG in its ESG investing business, bringing the firm’s ESG-dedicated AUM to $80 billion. Parnassus will be AMG’s third Affiliate wholly dedicated to responsible and impact investing.

Jay C. Horgen, President and Chief Executive Officer of AMG, said:

“For nearly four decades, and across numerous market cycles, Parnassus has integrated fundamental financial and ESG research with the goal of achieving attractive risk-adjusted returns for its clients. As our third Affiliate wholly dedicated to responsible and impact investing, AMG’s partnership with Parnassus further enhances our strategic participation in ESG investing, one of the fastest-growing segments in the investment industry, and an area of increasingly significant focus for clients globally.”