M&A roundup: Plante Moran, Sax and GHJ expand

Plante Moran, a Top 25 Firm based in Southfield, Michigan, has added Tonneson + Co, a firm based in Wakefield, Massachusetts, expanding its footprint on the East Coast to the Boston area, effective July 1.

Tonneson is one of the largest accounting firms in Boston and has been recognized on Accounting Today's Best Accounting Firms to Work For list for seven years in a row. It has a team of over 100 professionals.

"For 100 years, Plante Moran has prioritized long-term stability and client success, which has fueled the firm's steady growth," said Plante Moran managing partner Jason Drake in a statement Monday. "Tonneson's shared values and vision for the future make them an ideal partner. We're excited to welcome their talented team and expand our presence in Boston."

Plante Moran ranked No. 14 on Accounting Today's 2025 list of the Top 100 Firms, with over $1.1 billion in annual revenue and a staff of nearly 4,000 professionals, including over 350 partners.

"We're excited to join forces with Plante Moran — a 100-year-old, staunchly independent firm known for its award-winning culture," said Tonneson CEO Rick Mastrocola in a statement. "This partnership allows our combined firms to further enhance the capabilities we offer both clients and staff while preserving the unique culture and relationships that have defined Tonneson and Plante Moran for decades."

Last year, Plante Moran opened its first office in New York City. In 2023, after Drake was elected as the eighth managing partner in the firm's history, he told Accounting Today he planned to build Plante Moran into a $2 billion firm. In 2019, Plante Moran acquired Planning Perspectives in Birmingham, Michigan, and in 2018 it merged in EKS&H in Denver.

Sax, a Top 75 Firm based in Parsippany, New Jersey, has acquired Sewald & Anastasia CPAs, based in Morganville, New Jersey, effective June 1.

The deal expands Sax's presence in Monmouth County and strengthens its real estate and private client service capabilities by adding founders Charlie Anastasia and Steven Sewald.

Financial terms of the deal were not disclosed. Sax ranked No. 66 on Accounting Today's 2025 list of the Top 100 Firms, with $109 million in annual revenue.

Steven Sewald & Co. merged with Charles Anastasia to form Sewald & Anastasia in 2023.  After nearly two years of growing their firm in South New Jersey, the two lifelong tax professionals and softball teammates saw the opportunity of joining Sax. For 30 years, they have served small to midsized businesses in markets such as construction, trucking, health care, and retail. This acquisition will bolster Sax's capabilities in these vital sectors.

Anastasia, who has been managing partner of Sewald & Anastasia, will join Sax as a partner, helping to strengthen Sax's real estate practice. Sewald will be joining Sax's private client services practice as a director. 

"This acquisition is strategic, as both Sax and Sewald & Anastasia are equally aligned in our service philosophies and our dedication to continued growth to best serve our clients," said Sax managing partner Joseph Damiano in a statement. "We are excited to welcome Charlie and his team to Sax. This partnership is a significant milestone for Sax, as our firm looks forward to leveraging this partnership to deliver enhanced value and innovative solutions to its clients across the region."

"I am thrilled to join Sax and contribute to the firm's already impressive legacy," Anastasia said in a statement. "This acquisition represents a unique opportunity to combine our strengths and deepen our commitment to delivering exceptional service to our clients. I look forward to working with Sax's real estate practice and helping our clients navigate the complexities of the industry with innovative solutions and personalized guidance."
As a result of the deal, Sax is now a 62-partner firm with 367 total employees and has five offices between New Jersey, New York, and Mumbai, India, and a remote team spanning 22 U.S. states. 

Will Walsh of 1LifeConsulting LLC consulted on the transaction.

In 2023, Sax merged in Schall & Ashenfarb CPAs, a firm based in New York. In 2022, Sax acquired David Weiss CPA, also in New York.

GHJ, a Top 100 Firm based in Los Angeles with clients in the movie and TV industry, has merged in Hacker, Douglas & Co., a firm that specializes in profit participation and entertainment accounting and is also based in Los Angeles.

GHJ's profit participation services practice has provided services to over 80 of the top 100 grossing films and over half of the 100 biggest TV shows, according to the firm, and it anticipates its reach will grow as a result of the addition of Hacker Douglas.

"We are thrilled to welcome the exceptional team from Hacker Douglas to GHJ," GHJ profit participation services practice leader Peter Klass said in a statement Tuesday. "Their decades-long legacy of servicing leading television series and major motion pictures aligns perfectly with the high standard of service our clients expect from us."

Hacker Douglas dates back to 1970 and has handled motion picture and television audits, merchandising, publishing and estate valuation, and expert witness and litigation support services for the entertainment industry.

"With GHJ's added depth and resources, our team is better positioned to support our clients' goals without sacrificing the high-quality service that has always defined our work," said Elaine Douglas, a partner at Hacker Douglas, in a statement Tuesday. "I am confident this will serve our clients well for years to come."

"GHJ's reputation and knowledge base are top tier in this industry," stated Wendy Mills, a partner at Hacker Douglas. "Both firms strongly believe in providing the best client service to drive the most successful outcomes on all audit engagements, so we feel confident that GHJ is the perfect home for Hacker Douglas."  

Hacker Douglas' team will join GHJ's profit participation services practice this month. The deal was facilitated by law firm Sklar Kirsh.

"This strategic decision — founded in the right cultural fit and top-class services — positions GHJ to continue to lead as a premiere provider of expertise in the entertainment industry," said GHJ entertainment practice leader Ilan Haimoff in a statement. "This allows our firm to enhance the support we provide to clients while remaining focused on delivering personalized attention."

Financial terms of the deal were not disclosed. GHJ ranked No. 100 on Accounting Today's 2025 list of the Top 100 Firms, with $62.17 million in annual revenue. It has 270 professionals and 23 partners across the U.S.

Five Hacker Douglas (acquired firm) team members are joining GHJ including its entire senior leadership team. GHJ has been a global leader in film/tv profit participations and contractual accounting, and now it has about 80% of the market share in the related services.

Last November, GHJ added GGF, another firm based in LA.