DAX is going crazy due to VW

Last week has been unique in the history of Germany's most important stock exchange, Deutsche Börse. Although the shares of other companies were in free fall due to the financial crisis, the price of VW shares rose in the first two days of the week by 225% to more than 1000 Euro. This caused the DAX to raise instead to fall. As a consequence, Deutsche Börse was forced to change its rules, which now allow for an extraordinary diminution of a company's weight in the composition of the DAX. Although the reasons for the spectacular rise of VW shares have yet to be investigated, it seems that short sellers, especially hedge funds, needed to cover bets that had gone awry. There have been rumors that Porsche, the majority shareholder, itself has sold stocks to these funds. Legally speaking, this is a problem of “market abuse”. But has the market indeed been abused or have some market participants just bet on the wrong horse? And how much does an index need to be legally protected against transactions like these? It seems that these questions must be answered from an economic perspective.