Why Tesla Stock Just Had Its Best Day in a Decade

Tesla (TSLA) stock notched its best day in more than a decade on Thursday after the electric vehicle maker topped earnings estimates and promised a lower-cost model would begin production early next year.  Tesla shares soared 22% Thursday, their biggest one-day gain since May 2013 when the company reported $500 million in quarterly sales for the first time. In the most recent quarter, vehicle sales exceeded$20 billion.  Tesla's surging stock lifted the S&P 500's Automobiles Industry Index, which advanced ...