A record wave of giant IPOs is being aimed at ordinary investors, and the pitch may be less about opportunity than about finding someone big enough to buy.

• Companies like SpaceX are preparing stock sales at the largest valuations ever seen.
• The only pool of money big enough to soak up that much stock is the trillions sitting in 401(k)s and index funds.
• Index funds buy whatever is in the index — they don't judge whether the price is fair.
• So getting added to a major index guarantees demand, no matter what the company is worth.
• That means regular savers end up owning these shares automatically, without ever deciding to.

Outlook: Expect more huge listings pushed toward index inclusion, with passive money doing the buying.