CHAPEL HILL, N.C. (MarketWatch) — It may have been just a coincidence, of course.

But the intraday low earlier Thursday for the S&P 500 SPX, +0.82% came almost precisely at this benchmark’s 200-day moving average — and from that level the market has bounced back. The S&P 500 now is nearly 1% higher, though it is still down for the day.