Bronfman Rothschild is being acquired by NFP Corp. and will be combined with Sontag Advisory to create a $10 billion registered investment adviser, the companies announced this morning.

NFP Corp. describes itself as an insurance broker, consultant and provider of wealth management, retirement and estate planning.

The mega transaction involving Rockville, Md.-based Bronfman Rothschild, which is expected to close by the end of June, will create a combined RIA entity led by the management teams of New York-based Sontag and Bronfman Rothschild.

Sontag, which NFP acquired in stages between 2005 and 2014, has nearly $5 billion under management and 10 financial advisers.

Bronfman Rothschild manages nearly $6 billion with 45 advisers.

David DeVoe, managing director at the investment bank DeVoe & Co., said the deal “shows the power of having a strong partner behind you.”

“NFP has the M&A acumen and deep pockets to be able to merge two firms of this size together,” Mr. DeVoe said. “It is part of a broader sub-acquisition trend, where consolidators share their M&A expertise and capital with their affiliate, enabling them to execute transactions that they couldn’t have done on their own.”

The deal is unique in that it marks Sontag’s first acquisition in its 23-year history.

Eric Sontag, whose titles of president and chief operating officer will not change once the deal is final, said that the advisory firm founded by his father, Howard, in 1995 had only recently started considering growth through acquisitions.

“Over the last couple of years, we became very open to the idea of acquisitions and we were actively searching, but it had to be the right place and at the right time,” he said. “We were never looking for just buying a succession plan. We wanted a strategic partner.”

Acknowledging the importance of scale in the financial advisory space, Mr. Sontag added that the Bronfman Rothschild deal could be followed by other acquisitions.

“We’re not setting a goal to make a set number of acquisitions, but we are interested in growth through acquisitions,” he said.

Daniel Seivert, chief executive at the investment bank Echelon Partners, was surprised to see a known acquirer like Bronfman Rothschild become a seller.

However, he said, the involvement of private-equity-backed NFP could signal some buying ahead for the combined firm.

“This gives NFP a more formal RIA platform to build off,” Mr. Seivert said. “This deal also shows that as you get larger, there are fewer buyers and you have to factor that into the thinking of your own liquidity event.”

For Bronfman Rothschild, which made four acquisitions in 2017 and one last year, the sale to NFP occupied a big part of the last six months of last year, said Mike LaMena, who is president and chief operating officer of Bronfman Rothschild and will become chief executive of the combined firm.

“It was definitely the primary focus during the back half of last year,” he said.

Sontag’s current CEO, Michael Delgass, who stepped into the role five years ago as part of the succession plan for Howard Sontag, will remain on the executive committee and focus more of his efforts on financial planning and business development in the Northeastern region.

“[Mr. Delgass] has a substantial client base that he serves, and his forte is really gaining and serving clients,” Howard Sontag said. “He had taken the CEO role because he was the logical person, but he is more than happy to take on his new role.”

Howard Sontag, who will remain as chairman of the executive committee, said the one piece not yet in place is the rebranding of the combined firm, which will be addressed after the deal closes.

“This rebrand will be an effort by both firms to work our way through,” he said. “I’m open to all suggestions.”