John Barber, who was chair of 1,700-lawyer Lewis Brisbois' employment practice, said as many as 140 lawyers could eventually join the new firm, Barber Ranen.
He said about 60 Lewis Brisbois lawyers are slated to join as partners.
Los Angeles-founded Lewis Brisbois did not immediately respond to a request for comment on Tuesday.
A 32-lawyer cybersecurity group left Lewis Brisbois to join Constangy, Brooks, Smith & Prophete in several cities in January.
Read More:Partner group leaves Lewis Brisbois to launch new law firm44-member Lewis Brisbois cybersecurity team jumps to Constangy firmOur Standards: The Thomson Reuters Trust Principles.