Traders and analysts cited several factors for the rebound, including data showing a slight rise in the performance of Man Group's AHL funds and the fact Man Group's funds may have benefited from a commodity price recovery.

They added the stock was helped by an upbeat note from Bank of America Merrill Lynch, which advised investors to buy Man Group's shares ahead of its interim results later in July.

"They are 'long' on commodities which have bounced, benefiting the stock," said Beaufort Securities' sales trader Basil Petrides.

Shares in Man Group -- in which the firm of leading hedge fund manager Crispin Odey has a stake -- rose as much as 11.1 percent to an intraday high of 155.30 pence, their best level in more than a week.

The stock was up by 8.9 percent at 152.20 pence by 1135 GMT, the best-performance in percentage terms on the pan-European STOXX 600 index <.STOXX>. Man Group was also set for its best one-day gain since February 2014.

Man Group's shares had fallen by around 10 percent over the last week, with global stock markets hit by worries over Greece's debt crisis and a sell-off in the Chinese stock market.

A Man Group spokeswoman declined to comment when asked about the stock's rally on Thursday.

Despite the gains, Man Group's shares remain down by around 5 percent since the start of 2015.

Man Group issued a cautious outlook in May, which took some of the shine off the company's record funds under management levels.

According to Thomson Reuters StarMine data, the majority of analysts have a "hold" rating on Man Group's shares, while a minority rate the stock as a "buy".

Man Group's top shareholder is fellow hedge fund Odey Asset Management, with just over 6 percent, followed by TIAA-CREF with just over 4 percent, according to Thomson Reuters data.

(Additional reporting by Nishant Kumar and Alasdair Pal; Editing by Keith Weir and Mark Potter)

By Sudip Kar-Gupta