Mary Barra repeats as Fortune‘s Most Powerful Woman after a year of dramatic improvement at the $152.4 billion in revenues auto giant. She ably steered GM through the ignition switch crisis that hit in 2014, made the tough decision to end operations in Russia, and invested in ride- sharing company Lyft. She also bought Valley startup Cruise Automation for $581 million. Oh, and she posted record profits in 2015 of $9.7 billion. What she hasn’t done is boost the stock, which remains flat even as markets hit new highs. As an extra vote of confidence, GM’s board handed her the chairman title in January.