Arkadiy Abramovich, who is the Russian oligarch’s oldest son, has bought a 26 per cent stake in Crosby Asset Management for £3m.
The purchase, undertaken through his investment vehicle ARA Capital, caused shares in the AIM-listed investment firm to rocket yesterday.
Abramovich bought the stock from Irish energy tycoon John McKeon, the entrepreneurial founding shareholder of Circle Oil, and investment banker Ilyas Khan.
The pair still hold significant stakes in the company, which is incorporated in the Cayman Islands.
Based in Hong Kong, the vehicle will focus on investments in natural resources in Australia, as well as North and South America.
Roman Abramovich built his Russian oil and gas empire during the early 1990s, amassing a fortune estimated at around £7.4bn.
Shares in Crosby closed up 48 per cent at 4.72p per share.