Ericsson lost a quarter of its market value after reporting a surprise drop in third-quarter profits on the back of weak network upgrade sales. Shares in the world's biggest supplier of mobile networks at one point fell 30 percent, the biggest ever intraday fall, before recovering slightly late in the day. Ericsson was due to release results next week but rushed them out a day after directors saw them and learned of an unexpected erosion in both profits and margins. Matt Cowan reports for Reuters.