This stock market comeback is unprecedented by one measure

The S&P 500 is connected the verge of doing thing it hasn't done successful astatine slightest 2 decades, according to Susquehanna.

Chris Murphy, Susquehanna's co-head of derivatives strategy, noted that 97% of S&P 500 stocks are up for the 3rd clip successful the past 5 trading days. If that holds done the close, it would beryllium the archetypal clip since astatine slightest 2000 that the broader marketplace scale has seen specified spot astatine the banal level.

Investors ticker the 97% marker due to the fact that the scale typically pulls backmost aft a time with that percent of its components up, Murphy said.

He besides noted that anterior to past week, this week marked the archetypal clip since Aug. 25, 2015 that 97% of S&P 500 components were up successful 2 of the erstwhile 5 trading days. After that, the S&P 500 rebounded astir 13% earlier making a caller debased six months later, helium said.

The alleviation rally seen this week follows a hard past period and 4th for the banal market, arsenic the large indexes slid and jittery investors grew progressively acrophobic astir the Federal Reserve's involvement complaint hikes and the probability of an incoming recession.

Through the week's archetypal 2 trading sessions, the S&P 500 is up much than 5%, connected way for its biggest two-day summation since 2020.

—CNBC's Michael Bloom contributed to this report.