Bob Pisani - Downtick Rule

http://seekingalpha.com/article/135644-why-not-a-downtick-rule

"Bob Pisani was right: if you want an uptick rule for shorting, why not a downtick rule for buying? Or someone would say that all buyers are just plain long term investors and there are no bull speculators? Unlike many, I think that honest speculation is what makes markets work, whether it's done on the long or the short side."

Yes, speculators should exist on both the long and short side!