what is the downtick uptick rule 
the downtick uptick rule also known as rule 80a was a rule that the new york stock exchange nyse had established to maintain orderly markets in a market downturn the rule was abolished in 2007 the rule stated that whenever the nyse composite index gained or lost more than 2 from the previous day that all sell trades on s p 500 stocks during an upturn in the market be labeled as sell plus and that all buy trades during a downturn in the market be labeled as buy plus these trades were flagged before execution in order to slow trading on s p 500 companies because it halted the use of program trades that usually trade in large volumes 6