Two weeks ago, Zynga projected it would sell 100 million shares in its initial public offering for $8.50 to $10 a share. 

It did. That translates into a market capitalization of $7 billion. With unexercised options, the market cap rises nearly to $8.9  billion.

But the results of Thursday's IPO had to be something of a disappointment. There was chatter on CNBC that the IPO would price at $12 a share. And Zynga originally thought it would sell its shares at $20.

A better gauge of investor sentiment about the company will come Friday when shares open for trading on Nasdaq under the ticker ZNGA.

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So what happened? IPOs have been a disappointment this year. Groupon (GRPN) went public at $20, jumped to $31.14 and then fell to as low as $14.85 on Nov. 28. The shares have recovered a bit and finished Thursday at $23.08, a 15% gain over the IPO price.

Other IPOs have performed weakly as well. LinkedIn (LNKD) went public at $45 and zoomed up to $109.97 but has slumped, ending Thursday at $66.38.

And while Michael Kors Holdings (KORS) went public on Wednesday at $20 and ended up 21% Thursday at $24.20, it closed below its opening price of $25.

One company, Newgistics, pulled its IPO, citing shaky market conditions.

In fact, small-cap stocks have had a miserable year. The Dow Jones industrials ($INDU) are up 2.5% this year, with the Standard & Poor's 500 Index ($INX) down 3.3%. The Russell 2000 Index ($RUT), which tracks small-capitalization​ stocks, is down 8.8%.

So there was some wariness about Zynga, not the least of which is that 94% of its revenue comes from Facebook, which is expected to go public in the second quarter of 2012.

The company was founded in 2007 by Mark Pincus, who named the company after a pet, an American bulldog.

Zynga's sales more than doubled through September, to $829 million, and it has earned $121 million since the start of 2010, according to its SEC filing. What is more, the top five games on Facebook are Zynga titles: "CityVille," "CastleVille," "FarmVille," "Zynga Poker" and "Words With Friends."

But some analysts have noted that use of some of its older games has been dropping. Moreover, it collects money from only 3% of 227 million users.

Earlier this week, Sterne Agee analyst Arvind Bhatia rated the stock "underperform" even before it priced.

"We think growth is slowing," he told CNBC. "We think margins are under pressure, and we think free cash flow, this year, has come to a standstill."

Others believe the company has the chops to expand beyond Facebook. Pincus is known as a driven taskmaster.