Tesla joined the S&P 500 on Monday after a streak of profitable quarters helped push its stock price up about 700% this year.
The electric vehicle maker has come a long way since the middle of last year when there were doubts about its ability to pay its bills.
Fans say sales and income are up, debt has been cut and CEO Elon Musk's company is the leader in battery technology and software.
But critics say there is a limited number of markets in which to sell high-priced Tesla vehicles, and if it weren't for the sale of pollution credits the company wouldn't make money.
Shares opened Monday down 4.3%
Tesla will move e-commerce firm Etsy into second place in terms of performance.
The S&P 500 is the broadest measure of the overall stock market.
To join it a company must be worth at least $8.2 billion, be highly liquid and offer at least half its shares to the public.
