Sometimes a strategy gives a positive return albeit a very small one. Therefore, a manager can use leverage to magnify his return. For example, a long-short manager can deposit 100M with his
prime broker in order to buy 200M of shares and simultaneously sell another 200M of shares, which gives a leverage ratio of (200M+200M)/100M = 4. As another example, a manager can borrow money from a country at an interest rate of 2% and reinvest the amount in another country that pays 4%, thus earning the spread 4\%-2\%=2\% (this is called
carry trade). If the manager has a leverage ratio of (say) 5 then his return is not 2% but 5\times 2\% = 10\%. However, leverage also amplifies losses: if a manager has a market loss of 3% in his portfolio and a leverage of 4 then his total losses are 4\times 3\% = 12\%. Therefore, even small market losses can be disastrous when there is a huge leverage. According to the
OECD, prior to the 2007 crisis, hedge funds in 2007 had an average leverage of 3 whilst investment banks had a leverage above 30. With a leverage of 30, a market loss of 3.3% wipes out the entire portfolio whilst a leverage of 3 gives a total loss of 10%. ==High turnover==