Merrill Lynch’s top-rated banks analyst has quit the firm along with several senior colleagues to form his own independent research boutique, in the latest high-profile departure to have followed the US investment bank’s takeover by Bank of America last month.

Stuart Graham, head of European banks research at Bank of America-Merrill Lynch, and the top-rated UK banks analyst, has quit the bank to form an independent research business along with senior colleagues Manus Costello and Ed Alchin, previously in specialist sales, according to two sources with knowledge of the situation.