The article in NY times explains it. The mistakes made by General Motors
The article states three mistakes - agreeing to expensive union contracts, not investing enough in smaller cars and failing to convert its plants so they could build more than one type of vehicle.
The Biggest Mistake as pointed out in the article was, "G.M.’s biggest failing, reflected in a clear pattern over recent decades, has been its inability to strike a balance between those inside the company who pushed for innovation ahead of the curve, and the finance executives who worried more about returns on investment."
If you hand over your company to accountants - be sure this is what you will get! It is imperative that you build your own dreams together -rather than helping accountants get their ROI formulas working and killing innovation!