Uptick Rule
Also called: short sale rule, alternative uptick rule, Rule 201
The uptick rule restricted short sales to prices above the last trade, on the theory that unrestricted shorting accelerates declines. The original was repealed in 2007 and replaced in 2010 with an alternative version that only bites after a stock falls 10% in a day. Evidence that either version meaningfully dampens declines is weak, which hasn't reduced how often its reinstatement is demanded.