In February of 2010, the SEC voted to instate the rule, which would temporarily limit short sales on a stock after it fell 10 percent in one day. Dissenting commissioners doubted the move would end debate on the issue. The rule required short sellers to exceed the highest bid for the remainder of that trading day and the following in short sales of that security.
SEC Chairman Mary Schapiro backed the rule. The SEC had solicited comment on five different proposals designed to prevent short sellers from dominating trading in a stock to drive the price down, under pressure from lawmakers.
The restrictions also involve instituting a circuit breaker to curb the widespread and legal practice of borrowing a company's shares, selling them and then purchasing them back when the stock declines, then returning to the lender, keeping the difference. 
- SEC votes 3-2 for alternative uptick rule. MarketWatch.