38.2% retracement of the move up from the July 30 swing low and 100 hour moving average
As trading heads in the last hour for US stocks, the S&P index just made a new session low at 3442.25. That took the price is just below its 100 hour moving average at 3447.92, but stayed just above its 38.2% retracement of the move up from the July 30 swing low (just before the start of the next run higher). That retracement level comes in at 3441.72.
Meanwhile the NASDAQ index is also trading at new session lows (down -5.36%). It has fallen below the 50% retracement of the move up from the August 11 swing low at 11418.387. It's 100 hour moving average is up at 11481.98. The last time the price traded below its 100 hour moving average was back on July 30.