Oct. 9 has loomed large in stock-market history. Why investors still shouldn’t buy into an October jinx.

Two major market turning points since 2000 have landed on Oct. 9. In 2002, the S&P 500 closed at a bear-market low before beginning a multiyear recovery; in 2007, the index peaked on that date before the financial crisis. The coincidence has given the date a reputation among market watchers, but it reflects two very different economic backdrops rather than any recurring seasonal force.

That is the key point for investors: a calendar date has no causal link to prices. Markets move on earnings, interest rates, inflation and credit conditions. October’s history of volatility — 1929 and 1987 are the best-known examples — stems from the fact that major shocks happened to occur then, not because the month itself changes market mechanics.

What to watch this October is the same as any month: the path of corporate profits, central-bank policy signals and bond yields. Those are the inputs that actually drive valuations. A memorable date is a useful reminder of how quickly regimes can shift — not a signal to act on.