When financial services company Square priced its IPO at $9 a share last November, well under the $15+ price that private investors paid the year before, it was a cold shower of reality for the 6-year-old company. The share price did rise during the IPO, but at the end of the day the firm’s value leveled off to around $4 billion, just two-thirds of the $6 billion Square supposedly had been worth. Until the IPO, Square had been one of more than 130 unicorns: privately owned tech companies valued at $1 billion or more.