The S&P closed the week on the 21 day moving average (the yellow line on the chart). It was down 5% this week, which started on a full moon. Back in March, when the index went above the yellow line, it has stayed above it(21ema), during this 2 month rally. If it goes below this line, that will trigger a short term sell signal, and next support will be at 850/825. If we stay above this yellow line, the rally will continue to 935/950.