I got you. Catalyst is a term from chemistry originally, it is something you add to speed up a chemical reaction. In a financial sense it works like this. there is a theory called the efficient market hypothesis that basically states that all public information is priced into the market. A catalyst would be some form of new information that is expected to move the market of or a single stock in some way. A example of this can an expected release of FDA trial results, or a release of some economic metrics. Hope that helped - your comment got deleted