The UK-based group reported revenue of £250m between November 2013 and March 2015 and profits of £243.6m – £191.2m of which was distributed to the firm’s 20 members.
One of the firm’s so-called members is listed as MS ARS Holding, a subsidiary of Morgan Stanley, according to US regulatory filings.
US bank Morgan Stanley owns a 19 per cent stake in Lansdowne, which it is reported to have put up for sale earlier this year.
Lansdowne was co-founded by Sir Paul Ruddock and Steven Heinz in 1998. The reins of the firm have since been handed to Stuart Roden and Peter Davies, who managed its flagship fund.
Lansdowne declined to comment.