As we have been discussing for weeks, supply continues in the S&Ps. Last week ended poorly, and the news media is beginning to report it (e.g., Dow falls below 12,000).
The rally on Thursday to 1288.50 (labled A on the chart) showed a distinct lack of demand.
The next level of support comes in at 1237.75 basis the June contract (now the front month). You can see on the weekly chart that if this level holds, a trading range will form. Lower support comes in between 1200 and 1150 should the 1237 area fail to hold.
The chart shows volume for June 9th of just under a million for the September contract (front month as of that day) however June was still being actively traded that day and its volume was 1.7 million.