In a very pleasant corner of San Francisco, Nasdaq is quietly expanding its West Coast operations. But it is not in town merely to persuade Silicon Valley’s hottest tech companies to prepare their initial public offerings. Far from it.

In March last year, the New York-based stock exchange quietly established a private platform for “pre-IPO” companies to raise capital and trade secondary shares. Some 60 companies now sit on the Nasdaq Private Market. And Nasdaq officials admit that some of these tech groups plan never to list at all.

This is a striking quirk of today’s American “markets” — and it should give investment groups and regulators pause for thought. Back in the last tech boom at the end of the 20th century, when a tech company swelled it usually tried to list swiftly on an exchange. Getting on to a public market gave a young company credibility — and it was essential if a company needed large chunks of capital for investment, or a mechanism to enable its early employees to cash in their options.