Tesla Inc. shares soared 17 percent on Thursday after the electric carmaker surprised Wall Street by delivering on Chief Executive Officer Elon Musk's promise of a profit in the third quarter, even as doubts remained about its long-term prospects.
Trading at $298, Tesla's market capitalization was $53 billion, surpassing General Motors Co.'s $51 billion stock market value and making it the United States' most valuable car company. It has been the No. 1 U.S. car company by market cap before, but recently GM has had a substantial lead.
Tesla late on Wednesday reported a quarterly profit, citing improvements in operating efficiency and a reduction in manufacturing and material costs.