Strong Open Fades Into The Close

I don't like when markets gap higher, lose momentum, but hold a higher close; this leaves them vulnerable to more selling the next day - particularly if such action occurs at the end of a rally (in an overbought state). We don't have this as markets have been range bound for a couple of weeks, even if overbought on intermediate stochatstics, but we need to be watchful. The S&P has been lingering near its 200-day MA as the 20-day MA fast approaches. There is a 'sell' trigger in the MACD, but other technicals are positive, including a particularly strong volume trend. While I would be bearish under such scenarios, this index is still in a bullish setup.