Hunton & Williams is opening a Boston office with a 14-attorney team that is splitting from litigation boutique Manion Gaynor & Manning, the firms' leaders announced Monday.

The team joining Hunton & Williams represents corporations in high-stakes litigation matters throughout the country, with clients such as American conglomerate Koch Industries and food services giant Sodexo. The group also represents ownership and management of some of Boston's top professional sports teams, as well as athletes, agents and coaches.

The lawyers will join Hunton & Williams on April 2, the same day the Virginia-founded firm is set to complete its merger with Texas-based Andrews Kurth Kenyon.

Harry Manion III and Martin Gaynor, founding partners of the 100-attorney litigation boutique, are among the lawyers joining Hunton & Williams. Gaynor, who was head of the firm's commercial litigation practice, will become managing partner of Hunton & Williams' Boston office.

Others joining Hunton & Williams include former Massachusetts Attorney General Tom Reilly, joining as special counsel; partners Christopher Cunio and Michael Perry; counsel attorneys Lawrence DeMeo, Timothy Fazio and Nicholas Stellakis; and six associates.

In an interview, Manion said client conflicts between the torts side of the boutique and the commercial litigation side contributed to his decision to leave the firm. “It was really conflicts-driven,” as the two sides of the firm were “knocking each other out of cases,” he said, adding he is leaving on good terms.

“It's really a business decision,” Manion said.

The majority of the lawyers staying at the firm focus on asbestos and other torts litigation, Manion said. The remaining firm, whose name will change, is led by John Manning, who directs the defense of more than 200,000 asbestos lawsuits, according to his firm profile.

Manning did not immediately respond to messages seeking a comment about the split.

Manion said another factor in the move to Hunton & Williams was the group's large, high-stakes litigation cases. “It became more and more clear to Gaynor, who runs the practice, and I, the chief trial lawyer, [that] we need more resources,” Manion said. “We could continue where we were going, with contract attorneys,” or join with another firm, he said.

While Manion said the boutique had been approached by other large firms, it entered talks with Hunton & Williams about a year ago because the two firms and key partners have worked with each other closely for two decades and have some of the same clients.

They had often referred cases to one another and worked together as co-counsel. For instance, the two firms together represented Invista B.V., a subsidiary of Koch Industries, in a Southern District of New York lawsuit brought against DuPont. The suit settled after seven weeks of trial in 2012.

The group's clients are moving to Hunton & Williams, Manion said, adding they received the personal endorsement from the general counsel of Koch Industries and Sodexo to make the move.

'Phenomenal Opportunity'

Wally Martinez, Hunton & Williams' managing partner, said the litigation group has already referred some transactional business to Hunton & Williams in the last four months, including M&A, labor and energy finance matters. “We really do think this will be a two-way street,” Martinez said.

At Hunton & Williams, about 60 percent of the firm is transaction-focused and 40 percent is disputes-based. “We're not a predominately litigation shop,” Martinez said, “so you have to look and find those people who work really well” in a collaborative environment.

In 2016, Hunton & Williams grew its gross revenue 2.5 percent to $541 million, with its revenue per lawyer at $820,000 and profits per partner at $1.1 million. The firm's 2017 revenue—reflecting a fiscal year ending March 31—will be reported in The American Lawyer's May issue.

“It's not going to be in the least dilutive in terms of economics,” Martinez said about the litigation team's addition, declining to provide an estimate of their book of business.

The firm had been eager to establish a foothold in Boston, Martinez said. “Not having something in New England is a glaring hole,” Martinez said. “The thing about Boston is that it's highly competitive, with great law firms there.”

“You try to be patient, so when the right talent comes up,” he said, “you have to move on it. This is a phenomenal opportunity.”

Hunton & Williams has taken over one floor of the boutique's offices in Boston and wants to grow the office with other practices, Martinez said.

The litigation boutique goes back to 1984, when the late Earle Cooley and Manion left Boston firm Hale and Dorr, now known as Wilmer Cutler Pickering Hale and Dorr, to found a firm that became Cooley Manion Jones.

In 2013, the litigation firm split into two practices, Manion Gaynor & Manning, and Jones Kelleher, with the latter focusing on personal injury and medical malpractice. At the time, Manion also cited conflicts for driving the split.

Manion has represented owners or management of major Boston teams, including the Celtics, Red Sox and the Bruins. According to his firm profile, he has also represented corporate clients Nike, Deltech Corp. and A.W. Chesterton.