There’s no question that mobile has been the most buzzed about sector in the advertising market this year. Global spending is expected grow from $1.3 billion this year to $13.5 billion by 2015. Most of the mobile search and display market is controlled by Google, but smaller firms are showing some muscle as evidenced by Millennial Media’s successful IPO earlier this month.

Millennial Media, an ad network based in Baltimore, MD, had hoped to go public at between $9-$11 a share. Investors began buying at $13 a share. By the end of its first day on the public market, share value rose to $25 which gave the company a valuation of $2 billion. Since then, the fervor has settled a bit and the firm’s shares are trading in the $18 range which is still good news. This kind of market activity shows investor anticipation of future growth in the mobile ad market.

This firm specializes in mobile display and holds about 17.7% of the market. Google and Apple are the top competitors with a 24.8% and 18% share, respectively. Millennial Media, with annual revenue last year of $103.7 million has captured plenty of attention.  The firm boasts relationships with impressive partners such as The New York Times, Zynga and Pandora.

Many advertisers perceive the mobile market as difficult to penetrate and manage. As a result, partners such as Millennial Media, which help remove the complexities of delivering ads to the myriad mobile devices and operating systems out there, are a welcome development. At the same time, these market complexities make  it difficult for competitors to quickly ramp up to scale which gives Millennial Media a first-mover advantage.

Industry observers note that investment activity has just started in this sector. Well-known venture capitalist firm Kleiner Perkins has funded InMobi and SessionM. And, Facebook recently rolled out mobile advertising.

It’s early yet in the life cycle of the mobile market and too soon to determine which players will be the biggest winners. But, as consumers continue to use their mobile devices more and their desktop computers less, there’s plenty of growth to come.

[Sources: United States. Securities and Exchange Commission. Millennial Media: 10-K.  Edgar Online. 2012. Web. 10 Apr. 2012; Patel, Kumur. Millennial Media’s Market Cap. Adage.com. 29 Mar. 2012. Web. 10 Apr. 2012; Kharif, Olga. Millennial Media. Businessweek.com. 30 Mar. 2012. Web. 10 Apr. 2012]