If you buy a stock, any stock and the next 2 days market is up more than 0.5% each day but your stock hardly moved or went down, then it is time to dump that stock and look for another one. Similarly, if the market is down more than 0.5% but your stock is down less or slightly up, then it is time to add more to the position as the stock is showing strength. If your stock is Tech related, compare it to QQQQ and if it is small cap compare it to IWM and if it is large cap compare it to SPY to find the relative strength.