FRANKFURT (Reuters) -Thyssenkrupp’s closely watched cash flow plunged deeper into the red in the second quarter, hit by restructuring costs and investments that overshadowed a guidance upgrade on the back of stronger demand and prices. Shares in the German conglomerate fell as much as 9.6% after the group said that negative free cash flow before mergers and acquisitions (M&S) widened to 750 million euros ($911 million), worse than analysts at Jefferies and JP Morgan had expected. “This is putting pressure on the stock,” said one trader, also pointing to profit-taking as inflation jitters triggered a global sell-off in equities. Returning to positive cash flow has been one of the key targets of the submarines-to-bearings group in its efforts to win back confidence among investors and to prove it has a sustainable business model. “We want and need to return to positive cash flow as quickly as possible,” said Chief Financial Officer Klaus Keysberg, adding that investments also need to be made to ensure the company can grow. Thyssenkrupp confirmed free cash flow before M&A would be negative at about 1 billion euros this year. Keysberg also toned down expectations ahead of a supervisory board meeting scheduled for May 19, saying no major decisions are planned for that meeting. Thyssenkrupp in February said it would come up with concrete proposals in May for how to develop its hydrogen division, which has drawn huge interest from investors. Thyssenkrupp is emerging from years of crisis, during which it lost two CEOs, warned on profits numerous times and sold its prized elevators division to private equity. Boosted by a global economic recovery that is driving both demand and prices for steel, car parts and materials, Thyssenkrupp also raised its full-year outlook for the second time in three months. The company now expects adjusted earnings before interest and tax (EBIT) in the hundreds of millions of euros in the year to September, having previously said it expects to almost break even. In the second quarter, adjusted EBIT came in at 220 million euros, the company’s highest profit in eight quarters. ($1 = 0.8234 euros) Reporting by Christoph Steitz and Tom KaeckenhoffAdditional reporting by Stefanie GeigerEditing by Kim Coghill, Louise Heavens and David Goodman Our Standards: The Thomson Reuters Trust Principles.