<P> When the current market price is less than the average price, the stock is considered attractive for purchase, with the expectation that the price will rise . When the current market price is above the average price, the market price is expected to fall . In other words, deviations from the average price are expected to revert to the average . </P> <P> The standard deviation of the most recent prices (e.g., the last 20) is often used as a buy or sell indicator . </P> <P> Stock reporting services (such as Yahoo! Finance, MS Investor, Morningstar, etc .), commonly offer moving averages for periods such as 50 and 100 days . While reporting services provide the averages, identifying the high and low prices for the study period is still necessary . </P> <P> Scalping is liquidity provision by non-traditional market makers, whereby traders attempt to earn (or make) the bid - ask spread . This procedure allows for profit for so long as price moves are less than this spread and normally involves establishing and liquidating a position quickly, usually within minutes or less . </P>

What do black tuesday dow jones industrial average 16 million trades pertain to