Santoli’s Friday market notes: S&P 500 snaps its downward trend and nears 4500, but will it stick?

A trader works on the floor of the New York Stock Exchange (NYSE) in New York, Sept. 20, 2021.
Michael Nagle | Bloomberg | Getty Images

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

  • Respectable follow-through to yesterday's strong rally, as the market works to make the case that a consequential seasonal bottom was made last week after a six-week testing phase that reset investor expectations and the average stock's valuation lower.