Assuming Tesla closes at a higher valuation than GM, it will rank the sixth-highest valued carmaker by market cap, behind Toyota, Daimler Volkswagen, BMW and Honda. While Tesla's Chief Executive Officer Musk, 45, has a long way to go to match Toyota's US$172b ($247b) market cap, Honda is barely ahead at about US$52b ($74.7b).
"The market cares more about the potential new market value of the other businesses Tesla is in than about real profits and cash flow," said David Whiston, an analyst at Morningstar Inc. "Right now there is nothing to slow Tesla's momentum. They could pass Honda, too."
Tesla has long been treated like a technology stock with investors betting on its ability to dominate a market for electric cars and energy storage. To those same investors, GM and Ford are headed for a slowdown in car sales that will erode profits.
"Is it fair? No, it isn't fair," Maryann Keller, an auto-industry consultant in Stamford, Connecticut, said of GM ceding the market-cap crown. "Even if Tesla turns a profit, they will eventually have to make enough to justify this valuation."
GM has fallen from grace before, of course. The Detroit-based company filed for a government-backed bankruptcy in 2009 and returned to the markets late the following year.
At the height of GM's power in the U.S., former CEO Charles Wilson famously said when nominated to be then-President Dwight Eisenhower's defense secretary: "For years I thought what was good for our country was good for General Motors, and vice versa."
Tesla delivered fewer than 80,000 vehicles globally last year to GM's more than 10 million. Musk's more-affordable Model 3 sedan, scheduled to roll out later this year, will be critical to his ambitions for Tesla to transform from niche carmaker into a mass-market manufacturer.
The Model 3 is expected to sell for about US$35,000 ($50,000) and boast at least 215 miles (350 kilometers) of battery range per charge, marks GM achieved with the Bolt that began selling in California earlier this year.
"Tesla's products have a captivating impact on consumers and shareholders alike; this advantage will be difficult to replicate," Potter, the Piper Jaffray analyst, wrote in a report Monday. "Even if the Model 3 production launch goes badly, we think customers (and more importantly shareholders) will withhold judgment."