A set of criteria used to help an investor narrow down which financial instruments or conditions of financial instruments are the most profitable. Taobiz explains Filter Most beginner investors feel overwhelmed by the large number of financial products available in each type of market. Filters help narrow down the investor's or trader's search, so the decision of which securities to trade is less complicated. Filters are not limited to finding companies by stock screeners; technical analysis tools can also help an investor or trader find a particular financial instrument. For example, if a trader wants to find financial instruments that are trading above their 200-day moving average, he or she can use a filter to find such instruments.