Chart courtesy of stockcharts.com
BPI - Bullish Percent Index is a popular market breadth indicator, which is calculated by dividing the number of stocks in an index with Point & Figure buy signals, by the total number of stocks. BP levels above 70% are considered overbought, whereas levels below 30% are considered oversold.
Strong buy signals occur when the Bullish Percent Index falls below 30% and then reverses up by at least 6%. Conversely, promising sell signals occur when it goes above 70%, and then reverses down by at least 6%.