Mike Santoli's market notes: New low for week, untrustworthy bounces, stay-at-home stocks fall

A stock trader wearing a mask walks near social distancing signs the day a new IPO is launched at the New York Stock Exchange as the city continues Phase 4 of re-opening following restrictions imposed to slow the spread of coronavirus on August 27, 2020 in New York City. The fourth phase allows outdoor arts and entertainment, sporting events without fans and media production.
Alexi Rosenfeld | Getty Images

This is the daily notebook of Mike Santoli, CNBC's senior markets commentator, with ideas about trends, stocks and market statistics.

  • The indexes drifting entirely within the week's range, until just now when the S&P 500 fell to a new low for the week. Overnight bounce attempts have been untrustworthy this month and late-day selling has been a feature — a switch that implies investors found themselves in September a bit too exposed to the popular big index stocks.
  • The daily low in the S&P 500 three of four days this week was within a few points of 3330. That's where the index close Aug. 11 – a handy date from which to mark the start of the acceleration into an upside overshoot, as TSLA announced a split and the call-options chase really got going. It's also less than half a percent above the 50-day average – something often hit/breached in a correction but also an area that in bull markets typically attracts and rewards dip-buyers.