Hedge-fund legend Stanley Druckenmiller, who has never had a losing year in his three-decade career, told his 100 clients Wednesday that he's shutting his firm, according to a media report.

Druckenmiller said he was tired of the stress of managing clients' money and having to match his own near-peerless record, according to a report by Bloomberg. Druckenmiller's Duquesne Capital Management, which oversees $12 billion in assets, has averaged a 30% annual return since 1986 but is off 5% in 2010.

"Managing more than $10 billion seems to challenge my long-term standard" for investment performance, Druckenmiller told Bloomberg in an interview. "For 30 years, I've been responsible for managing client money, and it's been a joy, but at some point I need to move on. Thirty years is enough."

Druckenmiller, 57, is perhaps best known for generating $1 billion for hedge-fund icon George Soros by forcing a devaluation of the British pound in 1992.