Is the party over? Has this winter’s sell-off, set off by inflation and rising interest rates, finally slowed the bull market that has pumped up private-company valuations, initial public offerings (IPOs), and stock prices since the late 2000s? The S&P 500 is off a modest 5% from its peak late last year, but the hottest sectors look much worse: Software indexes are down 20% in the same period. And the S&P 500 Biotech Index has dropped by more than 40% since its high a year ago. And yet there is still so much investor money chasing profits that 2022 could still prove a fertile year for new stoc…