MUNICH, Germany—Wacker Chemie A.G.'s supervisory board appointed Tobias Ohler to the executive board, effective Jan. 1. He succeeds Wilhelm Sittenthaler, executive board member and personnel director who was scheduled to step down from the company Dec. 31. Ohler's contract is for three years. Currently, Ohler is executive board member and personnel director of Wacker's subsidiary Siltronic. Sittenthaler, whose executive board contract expires at the end of April 2013, said he had to step down early due to personal reasons. Sittenthaler joined Wacker Chemie GmbH in 1980 and held a variety of positions. In 1996, he was appointed head of the Fluids, Resins and Silanes business unit at Burghausen in Germany. In 2000, he joined the executive board of Wacker Chemie GmbH and in 2003, he took over as president and CEO of Siltronic A.G. He assumed his most recent position in 2008. Ohler worked as a consultant at McKinsey from 1997 to 2004. He joined Wacker Chemie A.G. in 2005 as head of corporate controlling and, in 2008, became head of Raw Materials Procurement. In February 2010, he was appointed executive board member and personnel director of Siltronic.