The post-IPO rout for SpaceX (SPCX) is offering up a painful reminder to the average investor on two fronts. 

One, a hyped-up IPO is more of an exit moment for investors who got in early. And two, share prices are often volatile after the public listing, as investors dig in on near-term performance potential and anticipate insiders dumping their stock when lockups expire.

Quick analysis: SpaceX stock is trading at a record low, down about 31% from the first day’s closing price. Over the past 15 years, the one-year decline from the first-day closing price has been 52%, per Creative Planning (chart below). 

Only five companies from the list notched a positive return one year after going…