The NYSE Saw Its First 80% Downside Day Since December Last Week. What Comes Next?
As noted in last Thursdayâs evening update (AI Rout Sends the Tech Sector to Its Worst Day Since the Covid Crash), the 4.4% drop in the S&P 500 brought the first 80% downside volume day on the NYSE in nearly a year. That means at least 80% of NYSE volume was in declining stocks. It ended a 243-session streak without one, which BTIGâs Jonathan Krinsky says was the longest in at least 30 years (via Daily Chartbook).
Krinsky notes that an 80% downside day is often part of a bottoming process, but itâs rarely a one-off. Since 1996, there have been 15 previous times when the NYSE had its first 80% downside day in at least three months. In 11 of them, at least one more came within the next 30 sessions, and in five there were five or more. His bottom line is that âwe should not be surprised to see another one, if not several.â

Near-term returns havenât been great. The S&P 500 was lower on average one and two weeks later, down 1.0% and 0.6%, and higher only 40% and 47% of the time. A month later it was up just 0.3% on average, and higher 53% of the time. Two months out, the median gain was 4.2%, but the average was just 0.4%, dragged down by January 2020, just before the COVID crash.
Going through the cases, though, what mattered was whether more 80% days followed. In the five cases with five or more within 30 sessions (March 2004, January and October 2018, January 2020 and March 2025), the S&P 500 was higher 50 sessions later just once, with an average loss of 6.9%. The exception was March 2025: five more came during the tariff selloff, and the S&P 500 was still up 8.2% 50 sessions later. In the other 10 cases, it was higher 30 sessions later nine times (an average gain of 3.5%) and 50 sessions later eight times (4.8%).

One caveat is Thursdayâs drop was bigger than the day-of drop in any of the 15 earlier cases; the largest previously was 3.3% in October 2018. The S&P 500 is up 2.3% from Thursday’s close through Tuesday. The thing history says to watch is whether more 80% days show up in the 30-session window, which runs through December 18.
Note: Whether volatility remains high is also the swing factor for the spot-down, vol-down signal I noted earlier (see below), which has pointed to gains a month out.







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