SpaceX stock closed Friday at $160.95, sitting 19% above its $135 IPO price—a number that looks like easy money to anyone watching from the sidelines.

But for investors eyeing a Monday purchase, the real story isn't Friday's pop. It's what history says happens next.

University of Florida Professor Jay Ritter, who has tracked IPO performance for decades, notes that 75% of IPO stocks rise on their first day of trading. That statistic feels reassuring—until you look at what happens over the following months and years.

Ritter's data, spanning IPOs from 1975 to 2021, tells a far less rosy story for anyone buying at the close of day one. The average three-year return was 21%—but that figure is heavily skewed by a handful of spectacular winners. The median return tells the real story: a loss of 25.7%.

Even shorter holding periods offer little comfort. Investors who bought at the first-day close and held for just six months saw an average return of negative 0.6%.

The pattern is consistent: buying at the IPO price itself produces meaningfully better outcomes than buying after the first-day pop, though even then, the median investor still loses money.

For SpaceX, the analysis comes with an added twist. Musk-related stocks have historically traded somewhat disconnected from traditional valuation logic, driven as much by narrative and ambition—Mars missions, reusable rockets—as by near-term fundamentals.

The takeaway for anyone tempted by Friday's 19% pop: history suggests the smart money was at the IPO price, not the day-one close—and patience, measured in years rather than months, may be the only strategy that has historically worked.