Early backers of AI startup Anthropic have seen enormous gains, a windfall for venture investors but a reminder of how closed off these deals are to ordinary people.

• A stake in Anthropic bought five years ago is worth roughly 1,500 times what it cost today.
• That turns $100,000 into about $150 million, and $10 million into billions.
• The gains are locked up in private shares, so only early venture investors and insiders captured them.
• The run-up reflects how fast money has poured into AI companies since 2020.

Outlook: Expect more pressure for ways to let regular investors buy into private AI companies before they go public.