Shares of Tesla debuted in the S&P 500 on Monday, ending sharply lower after a report about potential future competition from Apple.

Tesla stock (TSLA) closed at $649.86, down $45.14, or 6.5%, in its first session in the S&P 500. The shares were the biggest drag on the S&P 500, accounting for 0.07 percentage point of the index's 0.46% decline, according to Refinitiv data.

It was its steepest one-day drop in over a week, after Reuters reported that Apple is targeting 2024 to produce its own passenger vehicle that could include its own breakthrough battery technology.

The decline in Tesla's shares accounted for about 0.1 percentage points of the S&P 500's 0.4% decline for the day, according to Refinitiv data.

The electric car maker, headed by billionaire Elon Musk, is the most valuable company ever admitted to Wall Street's main benchmark and accounted for a 1.69% weight in the index ahead of Monday's trading. The shares had surged almost 60% since mid-November, when Tesla's debut in the S&P 500 was announced, and have soared almost 700% so far in 2020.

Tesla jumped 6% on Friday in frantic trading ahead of its S&P 500 entry.

Tesla's addition to the S&P 500 led index-tracking funds to buy $90 billion of shares by the end of Friday so their portfolios reflected the index, according to S&P Dow Jones Indices' analyst Howard Silverblatt. The change was effective prior to the open of trading on Monday, and Tesla is replacing Apartment Investment and Management Co.

Actively managed funds that benchmark their performance to the S&P 500 must now decide whether to buy shares of Tesla, and risk underperforming if Tesla's recent rally continues and they do not own the shares.

"We put off that decision because we really believe the stock was running up into its inclusion in the S&P and that those who are in it for the arbitrage would sell starting today, and at least today, we are right," said Tim Ghriskey, chief investment strategist at Inverness Counsel in New York.

California-based Tesla's rally has put its market value at about $616 billion, making it the sixth most valuable publicly listed U.S. company, although many investors view it as wildly overvalued.

Silverblatt said the S&P 500's 2021 price/earnings ratio rises to 22.6 from 22.3 following Tesla's addition.

Tesla is by far the most traded stock by value on Wall Street, with $18 billion worth of its shares exchanged on average in each session over the past 12 months, easily beating Apple, in second place with average daily trades of $14 billion, according to Refinitiv.

About a fifth of Tesla's shares are closely held by Musk, the chief executive, and other insiders.