Moving Day Average: CNBC Explains  Getty Images  The term moving
average is frequently used in relation to the stock market. But
what is it exactly and how important is it to investors? CNBC
explains.  What is a moving average?  It's a technical analysis
term referring to the average closing price of a security over a
specified time. The most common time frames used are 20, 30, 50,
100 or 200 days.  Here's how it works. A 50-day moving average
is calculated by adding up the closing prices of a stock over 50
days and then dividing the result by 50.  A 200-day moving
average is calculated the same way—by adding up closing prices
over 200 days—and dividing the result by 200. And the same
formula is used for 20, 30 or 100 day averages.  What do moving
averages tell investors?  Moving averages are used to spot
pricing trends—up or down—for stocks. This is supposed to, in
theory, help investors determine when to buy or sell a
stock.Moving averages are the most commonly used piece of
technical analysis for securitie