Glaxosmithkline Share News (GSK)

The FTSE 100 rebound on Friday morning after a five-day losing streak as strong gains in the mining sector lifted London's benchmark higher."Clients who went bargain hunting in the mining space after the aggressive sell-off earlier in the week have been rewarded this morning, as the sector bounces back strongly early on," said Matt Basi, the Head of UK Sales Trading at CMC Markets.Ahead of today's session, the FTSE 100 had lost 2.7% of its value after five consecutive falls as disappointing US earnings and concerns over global growth weighed on sentiment.First-quarter economic gross domestic product figures from China, a plummeting gold price and downwards revisions to global growth forecasts by the International Monetary Fund caused some volatile swings in the mining sector earlier this week. Before today, FTSE 350 mining stocks had fallen by an average 9.14% since last Friday.FTSE 100: Miners provide a liftMining stocks were performing well after a volatile week for the sector. ENRC, Vedanta, EVRAZ and Randgold were all making decent gains by lunchtime.Anglo American was also a high riser after announcing that production at its larger operations of iron ore and copper increased in the first quarter, when compared with last year, despite the company scaling back spending.Meanwhile, telecoms firm Vodafone was also in demand as rumours continue to circulate surrounding a buy-out of its 45% stake in its US wireless joint venture with Verizon. According to reports this morning, a deal could happen this year as fears about tax obstacles ease.GlaxoSmithKline was trading lower ahead of its first-quarter update next week. There were reports this morning that the company is being investigated over claims it paid off firms to delay the launch of cheap versions of its anti-depression drug.FTSE 250: Spectris plummets after weak first quarterSpectris, the electrical engineering firm, plummeted after reporting an 8.0% fall in first-quarter sales, reflecting a deferral of orders and shipment delaysHigh Street bookie William Hill surged early on despite reporting that growth had moderated during the first quarter. The firm did say however that the Grand National after the quarter-end was a "major success", beating its record win achieved on the race in 2009.Online information and events group Euromoney fell after announced that it has acquired a 75% stake in the Australian provider of investment forums, Centre for Investor Education.