This Aug. 8, 2018, file photo shows a Tesla emblem on the back end of a Model S in the Tesla showroom in Santa Monica, Calif. (AP Photo/Richard Vogel, File)

Eight months after it seemed headed for the corporate junkyard, Tesla is now worth more than General Motors, Ford and Fiat Chrysler combined, even though the Big Three together sell more cars and trucks in two weeks than Tesla does in a whole year.

Tesla's stock has increased fivefold to nearly $900 since June, reflecting a sense among investors that the company is well-positioned for the expected global shift from the internal combustion engine to batteries.

But some analysts think the stock run-up is just plain nutty for a company that has never turned a full-year profit.