The BATS Exchange, the New York Stock Exchange and the NASDAQ Stock Market jointly issued a letter to the Securities and Exchange Commission urging it to adopt a “modified uptick” rule that includes a “circuit breaker” feature to combat abusive short selling. The SEC is currently considering a number of measures in the short sale area including a re-adoption of the uptick rule it removed in 2007. The exchanges argued that the old uptick rule “would likely prove difficult to implement and enforce” in today’s current rapid trading and penny increment market environment. As such, the exchanges called for a simple uptick rule that would be triggered after the price of a stock has experienced a precipitous decline (e.g., a 10 percent drop) and would allow short sales only at a price above the highest prevailing national bid in combination.  

http://www.batstrading.com/JointShortSaleLetter