Giga-IPOs are a symptom of public markets’ giga-problem

AMERICAN STOCK indices’ record highs mask a problem: getting firms to list is getting harder. The number of initial public offerings (IPOs) fell from an annual average of over 400 in the 1990s to 115 in the past decade. This plus attrition and more firms going private has reduced the ranks of public companies in America from a peak of 8,000 in 1996 to 3,900 last year. Jamie Dimon, boss of JPMorgan Chase and Wall Street wise man, would like to see 15,000 or more. If companies steer clear of public markets, as so many now choose to, ordinary investors miss out on their dynamism.