Shares of General Motors Co. /zigman2/quotes/205226835/composite GM -3.00% rebounded early Tuesday as the strike affecting the company entered its second day. The stock gained 0.5% in early trading, breaking a four-day losing streak and after closing down 4.3% on Monday. About 50,000 GM workers entered a strike this week, at a cost to the company of about $50 million a day, according to analyst estimates. The strike affects more than 31 GM plants, the majority of the company's North American production. Shares of GM have gained 12% this year, compared with gains of 16% for the S&P 500 index /zigman2/quotes/210599714/realtime SPX +0.48% .