One of Charlotte's largest law firms is merging with a national powerhouse this month, creating one of the three biggest law offices in town, the firms said Wednesday.

Helms Mulliss & Wicker, which has more than 145 lawyers in Charlotte, Raleigh and Wilmington, is combining with McGuireWoods, a 750-attorney firm based in Richmond, Va.

McGuireWoods, which is among the 50 biggest law firms in the country, opened its Charlotte office in 1998.

When the merger takes effect March 31, the firm will keep the McGuireWoods name and will have about 160 attorneys in Charlotte, including 120 from Helms Mulliss & Wicker.

"We've been watching the market, and everything going on, and we're just doing what any business would do," Helms Mulliss Chairman Peter J. Covington said Wednesday from a conference room on the 30th floor of the firm's uptown office tower.

The merger is the latest sign of Charlotte's changing legal landscape, with national law firms flocking here for the big banks and businesses. Some attorneys worry the competition, along with clients' increasingly sophisticated legal needs, has put pressure on local firms, sparking talk of mergers.

Helms Mulliss had flirted with the idea of a merger with Charlotte's Kennedy Covington Lobdell & Hickman, but the firms decided to maintain separate practices in 2004.

Helms Mulliss has done well in the changing market, said Covington, who will become McGuireWoods' vice chairman. Its clients include Bank of America, Wachovia, the Charlotte-Mecklenburg Board of Education and The Charlotte Observer.

"We also know our clients are growing, and for our best interest and the interest of our clients," the merger made sense, he said.

The new firm will rank third in size in Charlotte, behind Kennedy Covington and Moore & Van Allen.

Helms Mulliss started talks with McGuireWoods several months ago, drawn to the firm because it shared clients, expertise and Southern roots, Covington said.

Last week, after discussions with clients and lawyers at both firms, the firm's owners and partners voted overwhelmingly to move forward with the merger, he said.

Both firms are expected to hold a final vote in coming weeks.

Richard Cullen, McGuireWoods' chairman, said partners there respect Helms Mulliss and support the merger.

McGuireWoods, which was established in 1834 and now has 15 offices worldwide, has a long history of growth through mergers, it said.

McGuireWoods merged with Blakeney & Alexander to establish a presence in Charlotte and a year later merged with Fennebresque, Clark, Swindell & Hay.

The merger with Helms Mulliss will boost the firm's presence in Charlotte and throughout North Carolina, Cullen said Wednesday.

"We have an aspiration to be a great national law firm," he said. "This is a giant step toward that."

Changing names

Helms Mulliss & Wicker was formed in 1922, when Fred B. Helms, a Wake Forest Law School graduate, opened his law office in Charlotte. Soon, William F. Mulliss, a Harvard Law School graduate, joined him.

Later, the firm became Smith Helms Mulliss & Moore and grew to be one of the biggest in the state.

In 2002, the firm split into two firms, and Helms Mulliss & Wicker was established in Charlotte. The new name reflected the addition of former N.C. Lt. Gov. Dennis Wicker, who joined the firm's Raleigh office in 2001.