Aug 26 (Reuters) - Axel Springer will acquire Politico in a deal that valued the U.S political news website at over $1 billion, according to a source familiar with the matter. The companies announced the deal on Thursday but did not disclose the terms. This marked the biggest acquisition for Axel Springer to date, as the German publisher stitches together a global network of digital news operations. The deal, in which Springer will also buy the remaining 50% share of its joint venture Politico Europe, follows its 2015 deal to buy Business Insider and a 2020 deal to buy a majority stake in business newsletter platform Morning Brew. Robert Allbritton, the owner of Politico, will continue as the publisher of the website following the deal, which is expected to close by end of this year. Politico was founded ahead of the 2008 U.S. presidential elections by defectors from the Washington Post with an aim to cover Washington and politics with the pace, analysis and rigor of sports journalism. Springer owns a rich portfolio of news outlets including Bild, Welt and Insider, and is active in more than 40 countries. U.S. private equity investor KKR, which owns around 48% of Springer, has been building up its portfolio of digital and media assets though the German media conglomerate. Separately, two people familiar with the matter told CNBC that Springer was no longer in talks to buy digital-news outlet Axios, which was founded by Politico co-founder Jim VandeHei. Springer and Axios declined to comment.