General Motors Co. (GM) said its passenger-vehicle joint venture in China was contacted by the nation’s antitrust regulator amid an industry investigation that has seen at least seven foreign carmakers cut prices. Shanghai GM, a venture between GM and SAIC Motor Corp. (600104), has “actively responded” since 2012 to requests from the National Development and Reform Commission’s price supervision and anti-monopoly bureau, and assisted with its investigation and research of the automotive industry, GM said in an e-mailed response to Bloomberg News yesterday.