The Palo Alto, Calif.-based online payments firm sold 5.4 million shares at $13 each, within the expected price range of $12 to $14 each. Lead underwriter was Salomon Smith Barney.

The stock opened Friday at $15.41 and by mid-morning had climbed to $18.51, up more than 42 percent.

PayPal, which enables any business or consumer with an e-mail address to send and receive secure online payments, was forced to delay its initial public offering last week after being hit with a patent infringement lawsuit from New York-based CertCo. Since then, it has filed updated SEC documents denying its technology infringed on CertCo's patent.

Then, new disclosures surfaced that banking regulators in Louisiana are ordering the service to stop brokering payments between online buyers and sellers there until the company receives a state money transmission license. Other states have expressed similar concerns.

PayPal, of course, gets a little piece of each transaction, so any state actions are direct threats to its revenue stream.

Venture capital firms that have invested in PayPal include Sequoia Capital, Nokia Ventures L.P., Clearstone Venture Partners and Madison Dearborn Partners.