Uptick

See: Uptick Rule.

Stocks trade up and down all the time. That is, they "tick" up a skosh and down a skosh.

Why the "tick" there? Well, it comes from the old, pre-computer era ticker tape, where each tick generally meant that a stock had moved in price a tiny bit, i.e. one standard unit of Shmoop. Upticks matter, because in very bad markets, the market regulators don't want yet more selling to pile on top of a stock that is already "finding its level," or finding its way lower price after having just announced a badly missed quarterly earnings estimate.

So sellers follow the upticks...which imply that there are at least some buyers at that price out there who want to own the stock at that level, i.e. where that uptick happened from $40.37 to $40.38. It's only then at the $40.38 that short sellers can come in and short the crap out of the stock, betting that it's on its way to $35 or worse.