Shares of Tesla tumbled 7% in extended trade on Friday after the electric car maker was excluded from a group of companies being added to the S&P 500, among them Etsy, whose stock market value is less than a 20th of Tesla's.

The decision by S&P Dow Jones Indices is a blow to Tesla investors who widely expected the company to join the benchmark stock index after a blockbuster quarterly report in July cleared a major hurdle for its potential inclusion.

S&P Dow Jones Indices said in a statement it was adding online craft seller Etsy, semiconductor equipment maker Teradyne and pharmaceutical technology company Catalent to the S&P 500, effective Sept. 21, and removing H&R Block, Coty and Kohls.

Shares of Etsy jumped 6% in extended trade, Teradyne rose 2%, and Catalent added 2%.

S&P Dow Jones Indices senior index analyst Howard Silverblatt declined to say why Tesla was not added to the S&P 500, which is tracke ..

"The market is continuously changing, and we need to reflect that in our indices," Silverblatt said.

With a market capitalization over $370 billion, Tesla is one of the most valuable companies on Wall Street. Even after a 16% drop in its share price from record highs this week, Tesla remains more valuable than 95% of the ..

Tesla bears point to looming competition from Porsche , General Motors and other longer-established rivals. They are also skeptical of Tesla’s corporate governance under Chief Executive Elon Musk, who in 2018 agreed to pay $20 million and step down as chairman to settle fraud charges.

Short sellers are betting $24 billion that Tesla’s shares will fall, among the largest short levels on record for a US company, in dollars, according to S3 Partners.