Divergences, excesses (like GNT, which we had on both exchanges today) and lopsided selling or buying (short term RSI getting excessive as it did today, all three major indices went under 30%). In end stage bear market you need few strings of these, since I still think we are in the middle of the cyclical bull for few more months, one or two days should be enough. If major support do not bring buying, if indicates that "smart money" is not ready for a bounce.