Norway\'s sovereign wealth fund lost $15 billion last year as European stock prices fell over uncertain growth prospects amid the debt crisis, the country\'s central bank said Friday. Investments made by the oil and gas rich country\'s sovereign wealth fund suffered a 2.5 percent loss in 2011 worth 86 billion kronor ($15 billion, 11.4 billion euros). \"The result reflects substantial declines in share prices in 2011 and increased uncertainty about government debt in the euro area,\" Yngve Slyngstad, chief executive officer of Norges Bank Investment Management (NBIM) which manages the fund, was quoted as saying in a central bank statement. \"Because more than half of the fund is invested in Europe, it is of great importance to us that authorities are successful in solving the considerable structural and monetary challenges faced by the euro countries,\" he added. The fund\'s stocks portfolio, half of which was invested in Europe, suffered an 8.8 percent loss. Fixed income investments brought a 7 percent return. Due to currency fluctuations and additional contributions by the Norwegian state the market value of the fund rose by 234 billion kroner to to 3.3 trillion kroner.