Lerach Coughlin, the law firm that broke from Milberg Weiss in a high-profile split last year, officially returned to New York City this week and opened an office in TriBeCa.

In May 2004, Milberg Weiss Bershad Hynes & Lerach, then the largest firm specializing in class action shareholder lawsuits, split in two after a dispute between William Lerach and Melvyn Weiss.

Mr. Weiss leads the East Coast half, now called Milberg Weiss Bershad & Schulman. The firm led by Mr. Lerach, based in San Diego, Calif., is Lerach Coughlin Stoia Geller Rudman & Robbins.

Lerach Coughlin already has offices in Melville, N.Y., and its lawyers frequently travel to the city.

“We’ll be using the office all the time because we have people in New York almost every day,” Mr. Lerach said.

No attorneys are here full-time yet, but they will be “in the near future,” Mr. Lerach said. A partner, Samuel Rudman, is in charge of the New York region, and another partner, Patrick Daniels, will lead the Manhattan office.

“It’s the financial center of the universe, so not only do we have cases here, but we have really important clients here that we advise and meet with. You just have to be present to take care of your clients,” Mr. Daniels said.

Mr. Daniels said he will spend about half his time in New York. He lives in California.

Mr. Lerach said he did not think the move would heighten the competition between Lerach Coughlin and its former firm.”I don’t think it would be possible to heat it up any more than it is,” he said. He added, “I don’t think this will make a big difference in the way we compete with each other. But we needed an office in Manhattan. It’s the financial capital of the world.”

“We continue to grow and increase the number of clients we advise, and the number of actions we’re involved in. This is just a reflection of that growth,” Mr. Daniels said.

Milberg Weiss could not be reached for comment.

An attorney with the Washington Legal Foundation, Paul Kamenar, said the new office makes sense.

“These are the two titans in the securities class action bar who are vying for lead counsel in securities cases,” Mr. Kamenar said. “Even though they’ve separated, they are obviously still competing. So it’s no surprise that Lerach would want to stake out territory in New York, in the backyard of Melvyn Weiss.”

Hanging over both firms, Mr. Kamenar noted, is the investigation into whether Milberg Weiss, before the breakup, paid clients to serve as lead plaintiffs in class action suits. Earlier this year, a California grand jury indicted Seymour Lazar, who allegedly accepted $2.4 million in kickbacks from Milberg Weiss. Attorney Paul Selzer was accused of funneling the payments to Mr. Lazar.

With more than 200 lawyers, Milberg Weiss was the largest firm specializing in class action shareholder lawsuits before it broke in two. Both firms have grown since then, Lerach Coughlin to 150 attorneys and Milberg Weiss to more than 120.

The firm’s unwieldy size was a factor in its dissolution, but stylistic differences between Mr. Lerach and Mr. Weiss were the primary cause.

“There was a difference in style between them, and that more than anything else led to the split,” an attorney who represented Lerach Coughlin during the parting negotiations, Robert Friese, said. He added, “Bill is a very, very aggressive lawyer, and Mel is, too. I think it’s fair to say Bill has more of a tendency to be stronger in expression of his feelings.”

When the firms divided their cases, Lerach Coughlin took the shareholder lawsuit against Enron and its banks, auditors, and lawyers. The plaintiffs have collected more than $7 billion so far, with some parties yet to settle.