William Blair Investment Management has signed a definitive agreement to acquire boutique investment advisory firm Investment Counselors of Maryland (ICM).

The financial terms of the acquisition were not disclosed.

Established in 1972, ICM is a $3.2bn institutional US value equity investment firm focusing on value driven investing across domestic small and mid-cap companies. It is led by Bill Heaphy.

ICM employees own a significant interest in the firm, while the remaining stake is with BrightSphere Investment Group.

The acquisition will help William Blair in delivering specialised value-added strategies to its global clients.

William Blair Investment Management global head Stephanie Braming said: “We are thrilled to welcome Bill and the ICM investment team to William Blair as our US value franchise.

“ICM’s collaborative, rigorous investment process and client-focused culture aligns well with William Blair’s culture and mission. Moreover, the team has established deep relationships with some of the most sophisticated investors over time and has a well-documented track record of success.

“This team will broaden and deepen William Blair’s value expertise and will add another strong pillar to our well-known U.S., international, and emerging markets small-cap franchise.”

Heaphy said: “By leveraging the full strength of William Blair, we will be well positioned to continue delivering value to our clients prospectively.”

The deal is expected to close in the second quarter of this year, subject to customary closing conditions.

In September last year, William Blair opened an office in Singapore to bolster its footprint in Asia.