Philippe Jabre is not a man a company wants shorting its stock. Yesterday the former star GLG hedge fund manager revealed that he had a £37 million bet that shares in HBOS would fall even further, having already lost 75 per cent of their value in the past nine months.

When the market closed it appeared that he was already on the money: shares in HBOS closed down almost 3 per cent at 261p each, well below the bank's rights issue subscription price of 275p.

That is exactly the kind of bet that the Financial Services Authority (FSA) is trying to deter. Jabre Capital Partners announced to the stock exchange that it had a short position on 0.27 per cent of HBOS only because new FSA rules force investors shorting more than 0.25 per cent of a company in a rights issue situation to reveal their hand.

It is difficult to judge yet whether the FSA's rules have had any effect. According to Data Explorers, which monitors stock lending, 9.82 per cent of HBOS's market capitalisation was on loan to short-sellers on June 23, the first day that investors were obliged to reveal their positions. Yesterday there was 7.59 per cent on loan. Investors' shorting of HBOS is above the FTSE 100 average of 4.42per cent but well below that of Bradford & Bingley, which has 18.23 per cent of its shares on loan.

HBOS is unlikely to welcome Mr Jabre's attentions. The 48-year-old Lebanese-born trader is well known for the speed at which he makes decisions and executes them, moving his funds more quickly than many other managers.

He is even better known for being fined a record £750,000 by the FSA in 2006 while working at GLG Partners. Mr Jabre was found guilty of selling short $16 million of Sumitomo Mitsui Financial shares after learning that the Japanese company planned to issue new convertible shares. The regulator could not prove that he had committed intentional market abuse.

After studying at the American University of Beirut, Mr Jabre earned an MBA at Columbia University in New York, trained at JPMorgan and then worked for Banque Nationale de Paris in London. He joined GLG in 1997.

Last year Mr Jabre, a keen off-piste skier, set up his own multi-strategy fund manager in Switzerland. He clearly has not lost his knack. Last year his flagship fund, into which investors have sunk $4 billion, was reported to have returned almost 10 per cent over 11 months. Mr Jabre is married with four children.