On May 18, 2010, the German Minister of Finance announced that naked short sales of euro-denominated government bonds, credit default swaps based on those bonds, and shares in Germany's ten leading financial institutions will be prohibited. This ban went into effect that night and was set to expire on March 31, 2011. On May 28, German financial market regulator BaFin announced that this ban would be permanent. The ban became effective July 27, 2010. The International Monetary Fund issued a report in August 2010 saying that the measure succeeded only in impeding the markets. It said the ban "did relatively little to support the targeted institutions’ underlying stock prices, while liquidity dropped and volatility rose substantially." The IMF said there was no strong evidence that stock prices fell because of shorting.