One of the reasons I think this is an interesting pattern is what the momentum indicators are telling us. Both the MACD and RSI have been making lower highs while also making higher lows throughout the formation of the diamond. Shown graphically, this results in a wedge, with both indicators working themselves into a corner precisely at their respective midlines. Which way will they decide to break?
Another reason I find this interesting is that we are almost to the point of resolution. In other words, the S&P can only trade within this pattern for a few more days, at most, before a breakout occurs. A breakout (or breakdown) could even occur today...which brings me to my next point.
Later today we have the FOMC announcement. As you well know, FOMC days bring immense volatility, even if the announcement is perfectly in line with expectations. So what happens if the announcement fails to meet expectations and disappoints? Conversely, what happens if they become unexpectedly dovish? Today's meeting could very well be the catalyst that brings resolution to our little diamond pattern. While I don't know which way it will break, I do know that when it does, it will be powerful and last for many weeks.