Thiele began to work for Knorr-Bremse in 1969 as a patent lawyer. He joined the company’s executive board (Vorstand) in 1985. That year, when the grandson of founder Georg Knorr wanted to sell his shares, Thiele was commissioned to find a buyer. During the process, Deutsche Bank told him that if he bought it himself, the bank would act as guarantor. He purchased a controlling stake and later became sole owner.

After becoming chief executive in 1987, Thiele initiated big structural changes and narrowed the group’s focus to braking technology. He joined the company’s supervisory board (Aufsichtsrat) in 2007. In 2018, he announced plans to take the company public on the Frankfurt Stock Exchange in what was considered the country’s second-largest initial public offering of 2018.

Thiele was the largest shareholder in the German airline Lufthansa as of June 21, 2020. When Lufthansa agreed to a state bailout amid the Coronavirus recession in 2020, Thiele raised his stake in the company from 10 to more than 15 percent.