Also found in: Dictionary, Thesaurus, Wikipedia.
An SEC rule that formerly prohibited a short sale except on a plus tick or a zero plus tick. That is, Rule 10a-1 disallowed short sales at a price below the price at which the security traded most recently. This rule was intended to prevent short sellers from artificially deflating a security's price so that it harmed other investors. It was also called the uptick rule. It was replaced by Regulation SHO in 2007. Some have argued for its reintroduction.
An SEC rule that prohibits the sale of borrowed stock when the last price change in the stock was downward. Part of the Securities Exchange Act of 1934, the uptick rule is designed to keep investors from manipulating stock prices downward by borrowing and selling shares in a declining stock. See also short sale.