Investors accepted negative returns to lend to the EU\'s bailout fund on Tuesday, according to the German central bank, which organised the auction of three-month debt. The EFSF fund sold 1.99 billion euros ($2.57 billion) of three-month paper at an average rate of -0.04 percent, the Bundesbank said, roughly the same yield as at a similar auction last month. A negative yield means that overall and over the life of the loan, investors agree theoretically to pay the EFSF to lend it money. But despite the poor returns, investors were keen to snap up the debt. The Bundesbank received bids worth 5.63 billion euros, giving a healthy cover ratio -- a closely watched measure of demand -- of 2.8. The EFSF, which was established with a total lending capacity of 440 billion euros, is due to be replaced shortly by a permanent rescue fund called the European Stability Mechanism, with 500 billion euros of firepower. The ESM was due to come into force on July 1, but was delayed due to legal challenges in Germany. With legal hurdles out of the way, the ESM is now poised to come into force officially on October 8.