What's going on?

Social media platform Pinterest made its stock market debut to much investor applause on Thursday � its share price immediately ballooned 25% (tweet this).

What does this mean?

In raising $1.4 billion, Pinterest hit the stock market with a share price of $19 � higher than the range it proposed earlier this month, which had valued the entire company below what private investors last determined it was worth.

Pinterest�s apparent success in initially �lowballing� its valuation � perhaps generating additional demand for its shares, since new investors thought they might get them at a discount to the Pin�s previous price � may interest Uber-watchers. The ride-hailing giant pulls up to the market in May, but at a lower valuation than investment banks mooted last year. Those banks may be hoping investors see Uber�s stock as a bargain too.

Why should I care?

The bigger picture: Zoom also hit the stock market.

Teleconferencing firm Zoom Video Communications has a rare trait among tech initial public offerings (IPOs): it�s profitable. Zoom�s Thursday debut saw tech-hungry investors send it 80% higher in early trading � and, like Pinterest, its initial share price had already topped previous proposals, thanks to rampant investor demand. Zoom�s valuation, however, was nine times greater than at its last private funding round.

For markets: Day one in such a big way�

A new stock�s first-day performance often determines whether investors see its IPO as a success, especially in the US. But buyer beware: while the average day-one rise of a new stock in the US is 18%, according to Bloomberg, most of that benefit accrues to existing investors as the clamor from new backers drives up the price of admission. What�s more, five years down the line, 60% of IPO stocks will be trading below their initial price. And there�s also a danger investors get a little muddled in their excitement: an unrelated company called Zoom Technologies saw its stock mysteriously jump 67% on Thursday…