Elite New York firms Simpson Thacher & Bartlett and Sullivan & Cromwell have bagged plum roles on the $45bn (£23bn) leveraged buyout (LBO) of utilities giant TXU – potentially the largest LBO to date.

Simpson Thacher is lead adviser to the bidding consortium, comprising private equity giants Kohlberg Kravis Roberts & Co (KKR) and Texas Pacific Group, which is being advised by Cleary Gottlieb Steen & Hamilton.

TXU, meanwhile, has handed advisory roles to both Sullivan and Cravath Swaine & Moore, which is acting for the company's management board.

A host of additional firms including Covington & Burling, Hunton & Williams, Stroock & Stroock & Lavan and Vinson & Elkins have all landed further roles on the bid.

If successful, the deal – which was announced today (26 February) – would be the largest LBO to date, trumping Blackstone's $38.9bn (£19.8bn) acquisition of US property giant Equity Office Properties, announced earlier this month.

Simpson Thacher advised regular client Blackstone on that occasion, with the Chicago-based property company calling in Sidley Austin.

Other recent notable private equity mega-buyouts include the $33bn (£18bn) acquisition of hospital chain HCA last August, which saw Bain Capital, KKR and Merrill Lynch Global Private Equity club together to fund the acquisition.

Simpson Thacher was lead adviser to the buyers on that deal, while Sullivan and Shearman & Sterling also bagged advisory roles.

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