Shares, which also opened at $25, traded as high as $27.90 during the day.

Baltimore-based Millennial Media priced its shares Wednesday night at $13, at the high end of the expected $11 to $13 range. Earlier this week, Millennial raised its expected range, from an original $9 to $11. The company sold 9.2 million shares, while selling shareholders sold 1 million shares.

Millennial Media helps mobile developers and advertisers come up with advertisements catered specifically to smartphones, tablets and other mobile devices. It is the largest independent player in the space, where it competes with offerings from Apple Inc and Google Inc. Millennial holds a roughly 17 percent share of the mobile advertising market in the U.S., according to market research firm IDC.

Millennial Media's IPO underwriters included Morgan Stanley, Goldman Sachs and Barclays. Shares are trading under the ticker "MM."