alt Hacker NewsThe initial buyers of the shares sold by Anthropic are institutional investors (mostly). That matching process is done by an investment bank they hire.
The trading price you see on the screen is - shortly afterwards the shares become publicly tradable on the exchange (or on all US equities exchanges, for US stocks). So in effect, the price shooting up on the public markets is actually bad for the company in that they might have left money on the table.
Sort of. IPOs are always undervalued because the entire block of shares gets purchased by the investment bank at the banks decided IPO price but then bears the risk of selling them at or above that price.