An eight-partner team has resigned from Clyde & Co's San Francisco office, the firm has confirmed, making it the second mass resignation in a month for the firm, following partner departures from the London office.

The U.S. team, which focuses on insurance coverage and monitoring within the firm's California practice, is setting up its own boutique law firm called Atheria Law, according to a person with knowledge of the situation.

The firm has confirmed that it received resignation notices from partners Joan D'Ambrosio, Bill Casey, Christina Terplan, Julie Hawkinson, Jamie Narbaitz, Christina Marshall, Eric Moon and David Jordan.

Several associates and other non-partners are also expected to join from the Clydes office, although no number has yet been confirmed, according to the person.

In a statement to Legal Week, a Clydes spokesperson said: "We can confirm that a San Francisco-based partner group, led by Joan D'Ambrosio and Bill Casey, focused on insurance coverage and monitoring work, is leaving our US practice.

"We wish the team well as they set up an independent law firm and are working amicably and constructively with them to achieve as smooth a transition as possible for all parties."

D'Ambrosio's team specialises in tech errors and omissions and cyber coverage and monitoring work, while Casey's group focuses on coverage and monitoring in the architects, engineers and lawyers space, according to the firm.

The two teams joined Clydes in 2008 from U.S. firm Duane Morris, having previously practised as a group at legacy Hancock Rothert & Bunshoft.

Earlier this week, Legal Week revealed that a six-partner team had resigned from the firm's marine practice in London. The departing partners also intend to set up their own boutique law firm, Preston Turnbull.