Mayer Brown’s merger with leading Hong Kong firm Johnson Stokes & Master was the largest of three merger deals involving US law firms to be announced over the Christmas break, in the latest moves by America’s top practices to expand beyond their domestic heartland.

Mayer Brown unveiled the news shortly after Paul Hastings Janofsky & Walker made its long-awaited German debut after brokering a deal to absorb a respected 27-lawyer Frankfurt boutique, while Kirkpatrick & Lockhart Preston Gates Ellis sealed a domestic merger with Dallas firm Hughes & Luce.