Millennial Media is currently the largest independent mobile ad network; its competitors have long been bought out by Google, Apple and other big fish looking to strengthen their hold on respective mobile ecosystems. That, however, will no longer be the case after the company’s upcoming initial public offering, which looks to surpass all expectations.

Reuters reports that the company is hoping to sell 10.2 million shares for $9 to $11 each, and has upped its previous maximum estimate of $75 million to $129 million. Millennial, currently the largest privately-held ad network operator in the market, will be listed under the ticker ‘MM’ in the New York Stock Exchange.

“The company, which is backed by Bessemer Venture Partners and Columbia Capital, said it will offer 9.2 million of the total 10.2 million shares in the IPO while the rest would be offered by certain senior executives.

Morgan Stanley, Goldman Sachs and Barclays Capital are acting as lead underwriters for the offering.”

Millennial will be using the capital it will receive from the public offering to strengthen its R&D operation and expand globally. We’ll likely see some very big updates in the latter category, considering the company’s existing development efforts have resulted in a lot of new innovations throughout the past new months.

One of the latest Millennial announced is their Engagement Program. While the name of the new service may not be particularly original the concept behind it is: marketers can use it to recognize individual viewers and avoid wasting screen real-estate if they’ve already seen a certain ad. Instead, a brand can display a different ad based on whether or not a user has seen the previous one, engaged with it, and so on.