Opera Software is making another acquisition to build out its mobile advertising business: It has either purchased or is close to purchasing mobile video advertising startup AdColony, according to sources with knowledge of the companies.

We’ve contacted both companies asking for comment. Opera spokespeople in the U.S. and Europe have told us that the company will not comment on market rumors, and AdColony has not responded to requests for comment.

One source said that they’d last heard the negotiations were nearly complete. The other said the deal had closed at a price in the low hundreds of millions (up to $275 million). Now, we don’t want to downplay the difference between a deal that’s done and almost done, but for what it’s worth, the “not quite done” source did acknowledge that their information might be a little out-of-date, and that a completed deal would be consistent with the timing that they’d be hearing about.

From what we understand, AdColony employees were told about the acquisition over the weekend.

Norway-based Opera is known for its web browser software for mobile handsets, PCs, and TVs, with its search results and content recommendations based around visual, tile-style interfaces. On mobile devices, one of Opera’s main selling points is its compression algorithms that the company promises give faster download speeds that use up less data, and therefore cost less to use.

But, as with other companies that make web browsers, Opera has developed other lines of business to help monetize that software. Those efforts include an app storefront and a mobile advertising network.

The latter business, which operates under the Opera Mediaworks brand, also includes AdMarvel, which Opera acquired in 2010, and other, more recent additions like apprupt, a German startup focused on rich media advertising. In all, prior to AdColony, Opera has made eight acquisitions in the past four years, with several of those to further its advertising business.

It looks like AdColony could be used in Opera’s effort to expand that network even further into video ads. 

Read more on this story at TechCrunch.