Squire Sanders and Patton Boggs LLP are merging to create a law firm that will be among the 25 biggest in the world. The firm, to be called Squire Patton Boggs, will have about 1,600 lawyers in 21 countries.

The announcement of the merger comes two weeks after Patton Boggs agreed to pay $15 million to settle Chevron Corp.’s lawsuit over the firm’s involvement in obtaining a $9.5 billion judgment against the oil company in Ecuador for pollution in the Amazon rain forest. A federal judge in New York ruled on March 4 that an attorney from another firm used bribery and fraud in procuring the judgment in Ecuador.

Revenue and profitability at Patton Boggs, which has about 400 lawyers, had declined consistently over the past five years, law firm consultant Peter Zeughauser said May 23. Even after a restructuring improved its prospects, it “needed to combine with a stronger firm to be sustainable,” he said.

The merger will transform the brand of Squire Sanders, Zeughauser said, “from being an Ohio firm to being a Washington, D.C., firm.”

The combination is part of a trend of “continuing robust merger activity” in 2014 after a “banner year” in 2013, according to data compiled by law firm consultancy Altman Weil. The organization reported 88 law firm mergers last year, up from 60 in both 2011 and 2012.

The merger is expected to take effect by June 1, according to a statement from Squire Sanders.