Elite US firms Sullivan & Cromwell, Shearman & Sterling and Simpson Thacher & Bartlett have bagged the lead roles on the $33bn (£18bn) buy-out of Tennessee-based hospital chain HCA.

The deal is the largest-ever private equity transaction and involves buy-out giants Bain Capital, Kohlberg Kravis Roberts (KKR), and Merrill Lynch Global Private Equity in the acquiring consortium.