Shares in steelmaker Thyssenkrupp plunged on Tuesday (May 11) - down around 9% by lunchtime. That after the German giant's closely watched cash flow plunged deeper into the red. Over the second quarter, Thyssenkrupp said it saw an outflow of 750 million euros - or about $911 million. That's more than double the figure this time last year. Returning to positive cash flow has been one of the main goals for the group, which also makes everything from submarines to bearings. It wants to win back confidence among investors, and show it has a sustainable model for the future. The firm is emerging from years of crisis during which it lost two CEOs, and warned on profits numerous times. It also had to sell its elevator-making division - formerly its crown jewel. Tuesday did bring some good news. Buoyed by global economic recovery, Thyssenkrupp raised its full-year outlook for the second time in three months. But it played down expectations for big moves on strategy at a board meeting due later this month. There had been hope for news on how it would develop its hydrogen division, which has drawn huge interest from investors.