Monday, January 19, 2026
It took just 33 days for the S&P 500 to plunge 34% during the COVID crash in early 2020. It was the fastest breakdown of its kind in modern U.S. stock market history. The swiftness stunned even the most seasoned investors.
Scott Minerd was the Chief Investment Officer at Guggenheim Partners and a Wall Street veteran who lived through the 1987 crash, the dot-com bust in 2000, and the 2008 financial crisis. In March 2020, he told CNBC, “In my entire career, I’ve never seen anything like the speed of this decline.”
The S&P 500 usually moves about 0.8% a day. These drops were nearly 10 times larger and happened in minutes.
During the tariff flash crash last April, we saw another quick selloff, with the market plunging by about 19%. Individual stocks were hit even harder. Some fell 70% in a matter of days.
The lesson is markets can be swiftly brutal.
So, what’s causing today’s volatility to accelerate?
This bull market is one of the narrowest on record, with popular AI stocks like NVIDIA and Google parent Alphabet accounting for about a third of 2025’s total S&P 500 gains.
When a handful of giant stocks carry the load, the entire market becomes fragile.
Also, algorithmic trading accounts for up to 80% of U.S. volume. These systems execute multiple orders in microseconds, pouncing on weakness instantly. Perhaps that’s why when you exclude the 2008 financial crisis, the 10 biggest daily percentage moves in the S&P 500 over the past 30 years have all occurred since 2020.
That’s what happens when machines run rampant and rookie traders react to social media posts.