The average closing price of a stock over a specified period. For instance, the 10-day MA is the average closing price for the past 10 days. Stocks are said to be in an uptrend when above their MA and in a downtrend when below. The most widely followed MAs are 50 days and 200 days. Long-term investors tend to look at the 200-day MA while active traders are more likely to pay attention to the 50-day MA. Many investors look at both. As a general rule, it’s best to avoid stocks trading below both their 50- and 200-day MAs.