/Tesla’s Addition to S&P 500 Shows Why Indexes Are So Weird – The Wall Street Journal

Tesla’s Addition to S&P 500 Shows Why Indexes Are So Weird – The Wall Street Journal


Aficionados of Tesla Inc. were celebrating last week as the electric-car maker was accepted into the S&P 500, propelling its shares up 22% in two days.

Step back from the extraordinary gains, and the fact that America’s seventh-biggest company by market value is only now to be admitted to the index of the country’s 500 most-valuable stocks is weird. But it is only the most obvious of many strange but stock-price-moving ways that indexes rumble markets. Indexes play two important but often conflicting roles: They measure broad…

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