By Robert Hof After a long wait for Facebook shares to start trading today, ticker symbol FB initially leaped past the $38 a share the company set last night for its initial public offering. Shares opened shortly after 11:30 a.m. Eastern at $42 a share, up about 10%. That made Facebook worth $118 billion, more than any other newly public company. But shortly after the opening, shares slumped back toward $40, up only 5%, then headed further back to $39. And there are still hours left to go before the market closes. The lack of a big pop doesn't affect the $16 billion-plus that Facebook raised in the IPO. Indeed, if shares close only a bit above $38, that means Facebook got almost every bit of the money it could get from the IPO, leaving little on the table for investors looking for a quick profit. As Benchmark Capital venture capitalist Bill Gurley noted in a tweet: "Well-executed IPO by both the mgmt team and i-banks. Media loves "POP," but "POP" cost company $$ and increases LT risk." But IPOs aren't just about raising money. They are a publicity event intended to cement a company's arrival as a solid corporate citizen and, at least when it comes to technology companies, a growth stock. A first-day pop, even a relatively small one, often provides a signal that a company is indeed a hot commodity. So the lack of a pop will have implications for the value of its stock as currency for acquisitions, and perhaps even more important, for other, if lesser, IPOs still to come. Underwriters and companies generally try to set prices so they leave room for a 10% to 20% jump at the opening. The lack of sizzle in Facebook's IPO appears to be weighing on other Nasdaq stocks. Zynga, LinkedIn, Pandora, and Groupon are all down.