Orrick Herrington & Sutcliffe is close to securing the biggest West Coast link-up in US legal history with a merger vote expected from Silicon Valley suitor Cooley Godward in a matter of weeks.

The ambitious merger bid looks set to create a top 10 US firm with more than $700m (£425m) in revenue and 1,150 lawyers – bringing together Cooleys’ respected corporate and litigation practices with Orricks’ profitable finance and public law teams.