A downward movement of one tick or more in the price quote. Many stock exchanges have an uptick rule that states that a stock can only be sold if the stock price has ticked higher than the last price at which a transaction has taken place. This is aimed at traders who want to sell short, and is designed to prevent snowballing declines in the market. Other exchanges have tick test rules that are essentially the same as the uptick rule: Stocks may only be shorted on so-called zero-upticks, which means that the transaction price is either higher than the last transaction price, or that the transaction price is unchanged but higher than the transaction price that preceded it. This is known as a zero uptick or zero plus tick. CFDs are advantageous for traders that are bearish on a stock, because there are no uptick or tick test rules associated with CFDs.