Thomas Middleton has joined Blackstone, the alternative investment group, as a senior managing director in New York, 18 months after being dropped as Merrill Lynch's head of telecoms banking.

Middleton joins Blackstone, which is one of the world's largest investors in buy-outs and manages real estate and hedge funds, as a senior managing director in its mergers and acquisitions advisory group. He will be working for Tony James, who joined Blackstone earlier this year and is seen as a possible successor to the firm's founders.