Twitter is in talks to buy mobile news app Circa (TWTR)

Twitter is in serious acquisition talks with mobile news app Circa, sources with knowledge of the discussions told Business Insider. No deal has been finalized and Twitter is just one acquisition route that Circa is exploring, the sources said. It’s unclear what Circa’s valuation is; the startup has raised nearly $6 million since its 2011 launch. Circa, which produces brief news stories for mobile devices, was founded by Matt Galligan. It has a long list of early-stage investors including Path CEO David Morin, Wordpress founder Matt Mullenweg, and Quotidian Ventures. Fortune’s Dan Primack previously reported that…