General Motors failed to disclose that it paid $600,000 for work done by an advertising agency where the wife of GM's chief financial officer works, the automaker said in a regulatory filing on Friday. Pernilla Ammann, who is married to GM CFO Dan Ammann, is chief operating officer and partner of Mother New York. The New York-based firm worked on a project to celebrate the centennial of the Chevrolet brand last year.