heavy-weight; heavy; heavyweight; behemoth(The economist: For good or for ill, multidisciplinary behemoths like Deloitte seem to be the future of professional services. nosorog)
extraweight; heavily-loaded train; heavy hitter(a person or company that has a lot of power, especially in business or politics. LDOCE. She spoke to a room full of political heavy hitters. Their company is one of the industry's heavy hitters. MWALD Alexander Demidov)