June 4, 2009
Without the uptick rule, I believe it is easier to manipulate price. Sell short a large number of shares and reinforce the short sale on a down day with less shares. Then buy back the large sale. It is just a little bit more difficult to drive down price when you need an uptick in a falling market. Without the uptick, it becomes easier to panic regular investors because they only see the market dropping, and selling doesn't reflect a short-sale until after the fact.