Citigroup and Lehman Brothers are advising Welsh, Carson, Anderson & Stowe on a $1.8bn (€1.4bn) acquisition after the US private equity firm used different banks to advise on a $850m deal last month.

Welsh Carson has agreed to acquire United Surgical Partners International, a provider of surgical facilities, for $31.05 per share in cash, a 13.4% premium above the last closing price.