GM reclaims most valuable US automaker title as Tesla shares plunge

General Motors reclaimed the title of most valuable American automaker as Tesla shares continued their plunge on Friday.

Tesla shares plummeted around 14 percent – the company's biggest one-day loss in nearly five years – on worries about the electric carmaker's future after U.S. securities regulators charged CEO Elon Musk with fraud.

Bloomberg data showed that GM ended Friday with a market cap just over $47.4 billion, as Tesla's dipped to $45.2 billion.

Ford remained in third most valuable with a market cap of nearly $36.9 billion.

Tesla's fall, along with a decline in Facebook following a new data breach, weighed on the Nasdaq composite Index, which was 0.1 percent to 8,046.35 at the closing bell.

The Dow Jones industrial average also gained 0.1 percent to 26,457.36, while the broad-based Standard & Poor's 500 index was essentially flat at 2,913.93.

The U.S. Securities and Exchange Commission on Thursday charged Musk with securities fraud, alleging he misled investors last month in "false" tweets about taking the company private.

Tesla shares have been volatile for years, but even by its standards, August and September have been dramatic.

Barely a year ago, the stock reached an all-time high of $385 as investors grew optimistic about its lower-priced Model 3 sedan, the car that is seen as critical to Tesla's goal of becoming a mass-market automaker. But by March, the company had lost about a third of its value as analysts worried about the difficulties it faced in achieving that goal as well as the company's large and growing debt.

There were signs of progress in the months after that, and investors cheered in June after Musk said Tesla was about to hit its goal of making 5,000 Model 3s a week. At the beginning of August things looked even better when he said production was improving and Tesla wouldn't have to raise more money, a step that could have knocked its stock price down.

Then, on Aug. 7, Tesla nearly matched its all-time high after Musk said he had lined up funding to take the company private in a deal worth $420 a share. But it was soon clear that no deal was imminent. The stock fell, shareholders sued, and the government launched a civil investigation and a criminal one.

Tesla stock plunged 14.5 percent to $262.88 in heavy trading Friday. That's down 31 percent from its closing price Aug. 7.