SHANGHAI — The company’s name appeared in ads for the local marathon. Its logo was emblazoned on the jerseys of two professional soccer teams in Spain. Its founder had been lauded by the government’s official television channel. To investors, it seemed like a safe bet. For years, it was. Then some of them tried to take their money out. Now as much as $5 billion is missing, the head of the company is in jail and in one city, angry investors took to the streets.