One Atlanta law firm, Needle & Rosenberg, is a small boutique operation looking for a big brother to give it stability during trying financial times. The other, Troutman Sanders, is a large silk-stocking Atlanta firm looking to grow both outside the city and into other practices.

The two law firms recently have merged with out-of-town firms, representing both ends of a trend of legal merger mania.

Troutman Sanders, a 650-lawyer firm started in 1897, announced Wednesday that it is merging with Ross, Dixon & Bell, a Washington-based firm with 100 lawyers. The move expands Troutman's footprint to 15 cities and three continents.

It was the nation's fourth-largest legal merger this year, according to Altman Weil, a legal consulting firm. The Troutman deal is the 43rd merger so far this year, compared with 60 all of last year, Altman Weil said.

"The pace of mergers has exploded this quarter," said Altman Weil principal Bill Brennan. He said corporations keep consolidating and want to be represented by big law firms.

Robert W. Webb Jr., Troutman's managing partner since 1993, when the firm had 167 lawyers, said the move doubles its Washington office to 105 lawyers. It also gives the firm an entry into fields such as defending insurers in large environmental lawsuits or when directors and officers are sued, two of Ross Dixon's specialities.

"It's much more difficult to build a practice from the ground up," Webb said of the additions.

The smaller Atlanta firm merging — the 25-lawyer Needle & Rosenberg — is a patent and intellectual property firm where many of the lawyers are also scientists.

It will become the intellectual property branch and Atlanta satellite office of Ballard Spahr Andrews & Ingersoll, a 550-lawyer firm based in Philadelphia.

Two years ago, founding partner Bill Needle said he resisted mergers because he didn't want to lose the culture of the firm he spent 25 years building. But Wednesday, he said small firms increasingly have a hard time attracting large clients and paying the salaries of lawyers with scientific specialties.

"Ballard allows us to present a more stable front," said Needle, who will stay with the firm. "This allows us to keep together our people here, a tried-and-true culture."