NEW YORK (CNNMoney) — Twitter has acquired TweetDeck, an application for organizing the display of tweets, for more than $40 million in a mix of cash and stock, according to sources close to the deal.

TweetDeck has been the subject of speculation about deals for months. TechCrunch surfaced reports, citing a $40 million-$50 million acquisition. The deal has yet to be announced, but papers finalizing the deal were signed Monday.

Although Twitter reps weren’t available for comment, the company’s PR account tweeted, “For all those who might be curious, we continue to not comment on rumors.” Betaworks, a key investor in TweetDeck, was not immediately available for comment.

Twitter has been known to either downplay third-party apps or acquire them. In the past, Twitter has scooped up popular Twitter iPhone app Tweetie, and partnered with photo add-on TwitPic as it launched its new interface.

After a management shakeup, with co-founder Ev Williams out and Jack Dorsey back as head of product, the company is focusing on building and owning Twitter’s most compelling features and interfaces.