For Square, the pricing decision has ramifications beyond the obvious. By going public at a lower-than-expected valuation — a down round — the company has triggered what is known as a ratchet, which requires it to give one class of investors more shares at the expense of others.

Image Jack Dorsey, the chief executive of both Square and Twitter. Credit... Justin Tallis/Agence France-Presse — Getty Images

The I.P.O. price is disappointing for the six-year-old Square, which has faced questions over the years about whether it can grow into — and ultimately beyond — its lofty valuation. More broadly, the company’s pricing is a test both of the appetite for technology offerings and of the disconnect between the boundless optimism of private company valuations and the realities of a scrutinizing public market.

“A big name like Square going public at a down round paves the way to wonder what Silicon Valley unicorns will do so now,” said Kaylan Tildsley, a partner at Triton Research, which researches private companies.

Still, potential investors are digging into the company’s prospectus and setting up meetings with management during the firm’s road show to market its stock, according to people briefed on the company’s plans. And from Square’s perspective, it may be better to take its chances in the public arena now than to wait until next year, when it could be competing for attention with other unicorns — start-ups valued at $1 billion or more — going through the same issues.