California engineering design firm AECOM Technology Corp. said on Sunday that it would pay $6 billion to acquire its engineering and construction rival URS in San Francisco. The purchase will make AECOM the second-largest engineering and construction company in the country.

AECOM turned to Gibson, Dunn & Crutcher for legal representation on the deal, while URS sought counsel from Wachtell, Lipton, Rosen & Katz and Cooley.