The advance decline line(ADL)  is a very useful tool in judging whether the market is running out of steam. I look at the ADL and compare it to the S&P 500 or Dow over a period of six months. If the S&P or the Dow is doing well compared to the ADL then I would conclude that the market is running out of steam because the market is being held up by the large cap stocks and there is probably distribution of most of the other stocks in the market.  I have read in a few places that it is better to use the WEEKLY ADL rather than the daily ADL because the daily ADL has a downward bias.