These are very powerful bullish and bearish long-term signals that every trader should know. I posted this in the PCX thread but believe it is deserving of its own thread.

A golden cross is a very bullish long-term indicator that happens when the 50dma (short-term data) crosses above the 200dma (long-term data). A lot of stocks are getting these golden crosses because the 200dma incorporates data going all the way back 10 months while the 50dma is a collection of just the last 2 and a half months. Are you sure the 200dma goes back 10 months? Yes! This is so because there are 4 weeks in a month and 5 trading days in a week so only 20 days of data is collected per month on average). So as of today (mid-July 2009) the 200dma takes data going back all the way to mid-September 2008 while the 50dma is a collection of data going back just to beginning of May. A death cross is the same thing except when the 50dma crosses below the 200dma. The golden cross is coming very soon for PCX (a stock I currently own). Here is the chart for PCX with just the 50dma/200dma for easy reading: