Former BlackRock manager Mark Lyttleton has pleaded guilty to two counts of insider dealing at Southwark Crown Court.
He will be sentenced on 21 December.
At the end of September, the FCA announced Lyttleton had been charged with three counts of insider dealing between 2 October 2011 and 16 December 2011.
The two stocks concerned are EnCore Oil and Cairn Energy and were traded by Lyttleton through an overseas asset manager trading on behalf of a Panamanian registered company.
At the time Lyttleton worked in the fundamental equity team at Blackrock.
Formerly a star manager, he ran the BlackRock UK Absolute Alpha fund from its launch in April 2005 until April 2013, at one point managing £2bn in assets.
He was privy to inside information by both working on deals concerning the stocks or via conversations with colleagues.
He purchased shares a short time before information became public.
The offence is punishable by a fine or up to seven years imprisonment.