UPDATE 1-Millennial Media's revenue forecast disappoints

May 14 (Reuters) - Mobile advertising firm Millennial Media Inc forecast second-quarter revenue below analyst estimates, sending its shares down 9 percent after the bell.

The company forecast revenue of $37 million to $38 million. Analyst on average were expecting $41.4 million, according to Thomson Reuters I/B/E/S.

Revenue for the first quarter rose 53 percent to $32.9 million, but fell short of estimates of $33.2 million.

Net loss widened to $4 million, or 32 cents per share, from $23,000, or 8 cents per share, a year earlier.

Excluding items, the company, which went public in March, posted a loss of 5 cents per share, in line with estimates.

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.

Shares of the company closed at $15.45 on Monday on the New York Stock Exchange.