Based on your financial expertise, provide your response or viewpoint on the given financial question or topic. The response format is open.

Why do moving average acts as support and resistance?
It's not stopped. Crossing a moving average is considered a signal to buy or sell. Yahoo stock charts offer the ability to add moving averages to the charts, and you can observe all stocks cross the line regularly.   As a contrast to Victor's charts, you can see that Apple, over the last two years, has traded above and below the 50 day MA. A believer in technical analysis using MA will observe a buy signal in Dec '11 just under $400, with a sell in mid-$500s in May. Moving averages are a form of following the trend, and work well when either trend is strong. It's when the stock is too close to the line that's it's tough to call whether it's time to be in or out.