For the first time, Tesla Inc's stock market value has eclipsed the combined values of General Motors Co and Ford Motor Co. The Silicon Valley electric car maker's stock rose about 4% at midday on Wednesday, hitting a record high and elevating its market capitalization to $88 billion. That is $2 billion larger than General Motors' and Ford's respective stock market values of $49 billion and $37 billion, combined.

Fueled by a surprise third-quarter profit, progress at a new factory in China and better-than-expected car deliveries in the fourth quarter, Tesla's stock has nearly doubled in the past three months.

The progress made by Tesla Chief Executive Elon Musk has defied short sellers and other traders expecting the automaker to be overtaken by long-established car companies, including GM and Ford.

Underscoring investors' confidence in Musk and his company's future growth, its market capitalization has outpaced its US rivals, even as their businesses dwarf Tesla's. GM and Ford each delivered more than 2 million vehicles in the United States last year, compared with Tesla's worldwide deliveries of 367,500 vehicles. While Tesla's recent progress has cheered supporters, many analysts and investors remain pessimistic about the company's ability to consistently deliver profit and cash flow.