Top representatives at IG Metall, Germany’s biggest union, will not approve a sale of Thyssenkrupp’s prized elevator division unless potential buyers give far-reaching concessions to employees, they said. The remarks come as Thyssenkrupp’s efforts to list or sell the unit, which some analysts believe could be valued at 17 billion euros ($18.8 billion) or more, with at least 10 bidders shortlisted to submit indicative offers. Labor representatives have always had great influence at the steel-to-submarines conglomerate and hold half of the 20 seats on its supervisory board, with IG Metall members representing the majority of those.