IDEX Corporation

The seasonal story is really one month's story — November. It has closed higher in all 10 Novembers, a concentration the rest of the calendar can't touch.

The strength looks broad-based rather than freakish: its average (+5.4%) and median (+6.1%) sit close together, so no single blow-out year is flattering the figure. No month is steadier: November's returns vary by just 2.7% year to year, and even its worst November in 10 years lost only 0.3% — the gentlest downside anywhere on its calendar. Better still, that strength is the stock's own and not just a buoyant market — November has outpaced the S&P 500 by +3.1 points on average. Few peers keep such company in November — the typical stock clears it just 62% of the time.

It doesn't stand entirely alone — March, May, and July have leaned firm as well, if less emphatically. At the other end of the calendar, June is the year's low point, though even there the stock has stayed positive on average (+0.8%), a sign every month leans up, and the edge isn't year-round — the stock has trailed the S&P 500 in October, December, and February. Its roughest month on record was a −15.8% October in 2018 — a reminder of how hard even a seasonal name can fall.

November has now closed higher 10 years running. Reassuringly, the tendency has held its shape: the recent five years still track the years behind them.

For a stock this dependable in November, the sharper question is the rest of the year — outside its strong stretch, the calendar gives far less to lean on.