There were 13 law firm mergers during the third quarter of this year, up from seven deals recorded during the second quarter, according to a new report from Altman Weil Inc.

Most of the quarter's mergers were tiny acquisitions, reflecting "the continuing caution of law firms in response to the recent economic turmoil," said Bill Brennan, principal of Altman Weil.

The meatiest deal reported was Boston-based Bingham McCutchen’s acquisition of McKee Nelson, a 120-lawyer firm with offices in Washington and New York. The merge formed a 1,100-lawyer firm called Bingham McCutchen LLP.

Also during the quarter, Washington-based Howrey LLP acquired Day Casebeer Madrid and Batchelder, a Silicon Valley intellectual property boutique.

While those two deals involved large firms, eight of the quarter’s 13 deals were all small regional combinations. Brennan explains that law firms are not looking to assume the risks inherent with big mergers right now and are instead scooping up small firms or groups of lateral partners with portable business.

There were 25 law firm mergers and acquisitions reported in the first quarter of 2009.