The former prime minister will offer hedge fund's executives a macro view about international geo-political situation and future trends.
According to some reports, Blair will be paid over £200,000 by Lansdowne Partners for delivering the speeches.
A spokesman for Blair said: "Mr Blair remains one of the most popular international speakers around. These talks for Lansdowne were organised by the Washington Speakers Bureau in the usual way. Mr Blair has not taken a job with Lansdowne Partners."
Mayfair-based Lansdowne Partners is one the City's biggest hedge funds, taking care of about $16bn of investments.
The fund profited from Britain's recent banking crisis by sensing in advance that bank shares would fall drastically. It is believed to have made hundreds of millions of pounds by short-selling them. The company also successfully bet on the collapse of Northern Rock.
Blair is one of the highest paid speakers on the international lecture circuit, commanding up to £150,000 for a single lecture. He has reportedly earned around £14 million since he stepped down as prime minister.