German industrial giant Siemens on Monday spun off its energy unit, raising 16 billion euros in one of the largest stock market debuts in Europe this year. Shares in Siemens Energy traded at 22.01 euros at open before sliding back to 19.91 euros at 0713 GMT. Siemens Energy, with its oil and gas, turbines, power transmission and related services businesses, joins medical devices arm Healthineers and lightbulb unit Osram on the stock market. edf/hmn/wdb