George Soros, in this extract from his latest book, does not claim short-selling makes no difference. He explains why it took off after 2007 - the ending of the "up tick rule". But first, his assymetric risk explanations are most interesting:
"...credit default swaps played a critical role in Lehman’s demise. My explanation is controversial and all three steps of my argument will take the reader to unfamiliar ground.
First, there is an asymmetry in the risk/reward ratio between being long or short in the stock market. (Being long means owning a stock, being short means selling a stock one does not own.) Being long has unlimited potential on the upside but limited exposure on the downside. Being short is the reverse. The asymmetry manifests itself in the following way: losing on a long position reduces one’s risk exposure while losing on a short position increases it. As a result, one can be more patient being long and wrong than being short and wrong. The asymmetry serves to discourage the short-selling of stocks.
The second step is to understand credit default swaps and to recognise that the CDS market offers a convenient way of shorting bonds. In that market the asymmetry in risk/reward works in the opposite way to stocks. Going short on bonds by buying a CDS contract carries limited risk but unlimited profit potential; by contrast, selling credit default swaps offers limited profits but practically unlimited risks. The asymmetry encourages speculating on the short side, which in turn exerts a downward pressure on the underlying bonds. When an adverse development is expected, the negative effect can become overwhelming because CDS tend to be priced as warrants, not as options: people buy them not because they expect an eventual default but because they expect the CDS to appreciate during the lifetime of the contract. No arbitrage can correct the mispricing. That can be clearly seen in US and UK government bonds, whose actual price is much higher than that implied by CDS. These asymmetries are difficult to reconcile with the efficient market hypothesis, the notion that securities prices accurately reflect all known information.
The third step is to recognise reflexivity – that is to say, the mispricing of financial instruments can affect the fundamentals that market prices are supposed to reflect. Nowhere is this phenomenon more pronounced than in the case of financial institutions, whose ability to do business is dependent on confidence and trust. That means that “bear raids” to drive down the share prices of these institutions can be self-validating. That is in direct contradiction to the efficient market hypothesis.
Putting these three considerations together leads to the conclusion that Lehman, AIG and other financial institutions were destroyed by bear raids in which the shorting of stocks and buying of CDS amplified and reinforced each other. Unlimited shorting was made possible by the 2007 abolition of the uptick rule (which hindered bear raids by allowing short-selling only when prices were rising). The unlimited selling of bonds was facilitated by the CDS market. Together, the two made a lethal combination. That is what AIG, one of the most successful insurance companies in the world, failed to understand. Its business was selling insurance and, when it saw a seriously mispriced risk, it went to town insuring it, in the belief that diversifying risk reduces it. It expected to make a fortune in the long run but it was destroyed in short order.
My argument raises some interesting questions. What would have happened if the uptick rule on shorting shares had been kept, in effect, but “naked” short-selling (where the vendor has not borrowed the stock in advance) and speculating in CDS had both been outlawed? The bankruptcy of Lehman might have been avoided but what would have happened to the asset super-bubble? One can only conjecture. My guess is that the bubble would have been deflated more slowly, with less catastrophic results, but that the after-effects would have lingered longer. It would have resembled more the Japanese experience than what is happening now.
What is the proper role of short-selling? Undoubtedly it gives markets greater depth and continuity, making them more resilient, but it is not without dangers. As bear raids can be self-validating, they ought to be kept under control. If the efficient market hypothesis were valid, there would be an a priori reason for imposing no constraints. As it is, both the uptick rule and allowing short-selling only when it is covered by borrowed stock are useful pragmatic measures that seem to work well without any clear-cut theoretical justification.
This graphic is not from George Soros. But, it provides further background. What about credit default swaps? Here I take a more radical view than most people. The prevailing view is that they ought to be traded on regulated exchanges. I believe they are toxic and should be used only by prescription. They could be used to insure actual bonds but – in light of their asymmetric character – not to speculate against countries or companies. CDS are not, however, the only synthetic financial instruments that have proved toxic. The same applies to the slicing and dicing of collateralised debt obligations and to the portfolio insurance contracts that caused the stock market crash of 1987, to mention only two that have done a lot of damage. The issuance of stock is closely regulated by authorities such as the Securities and Exchange Commission; why not the issuance of derivatives and other synthetic instruments? The role of reflexivity and the asymmetries identified earlier ought to prompt a rejection of the efficient market hypothesis and a thorough reconsideration of the regulatory regime."
For more see FT article: http://www.ft.com/cms/s/0/49b1654a-ed60-11dd-bd60-0000779fd2ac.html