BUZZ-Sophos sinks 23 pct to bottom of FTSE 250 after 'weak' billings outlook
** Sophos Group (Frankfurt: 2SO.F - news) shares plunge to bottom of mid-cap FTSE 250 index after the company reports disappointing H1 results and lowers full-year guidance
** Company says it expects "modest" improvement in H2 billings growth compared with H1, which traders say is disappointing
** One trader describes billings forecast as "weak" and Liberum analysts say H1 results were below expectations
** H1 revenue rose to $349.5 million from $296.8 million, but missed consensus of $354 million, according to traders
** Shares (Berlin: DI6.BE - news) down 23 percent after hitting lowest since April 2017 and on track for worst day since its listing in 2015 (Reporting by Josephine Mason)