Every day on CNBC-TV they show a 200-day moving average line superimposed on the stock price history. It seems they give great credence to this manufactured line as it represents 10 months of price action. What is it? Does it really mean anything?

The line represents the addition of the closing prices of that particular stock, mutual fund or index for the past 200 trading sessions that have been added up and divided by 200. That is then placed on the chart at that point. For example if the price of the equity started at zero and went up exactly one point for 200 days the average would be 100. A dot is then place on the chart at 100 even though the equity price is now at 200. Each day the new closing price is added after dropping off price number 1 and the new group is added up and divided by 200. This is done each day. Nothing complicated.

Does this mean anything?

This is considered to be a very useful technical indicator, but like all technical indicators you must understand how to use it. There is one rule for any technical indicator: no single one is a Holy Grail for predicting future price action of a stock, fund or index. WAIT! Don