Surge in 1 month lows

In the last few days, there has been a rapid increase in the percentage of stocks within the S&P 500 falling to their lowest level in a month. This is highly unusual with the S&P 500 index itself hovering within 1% of its high.

Going back to 1927, yesterday's reading is a record high. There has never before been more stocks sitting at 1-month lows with the S&P so close to its peak.

As for the "so what?" question, short-term returns following any day with more than a quarter of stocks hitting a month low were not great.

Not that this was not a good medium- to long-term sell signal. Six months later, the S&P was higher every time but once, and that was a tiny loss.