1. A list of securities being monitored closely by a brokerage or exchange in order to spot irregularities. Firms on the watch list might be suspected of regulatory violations, about to issue new securities, attracting usually heavy volume, etc. 2. A list of securities being monitored for potential trading or investing opportunities. An investor or trader may have a watch list of several, dozens or even hundreds of trading instruments. The investor waits for certain criteria to be met--such as trading over a certain volume, breaking out of a 52-week range or moving above its 200-day moving average--before placing trade orders.