Tesla (NASDAQ: TSLA) will be added to the S&P 500 index all at once at its full market capitalization before trade opens on December 21, S&P Dow Jones Indices said about the move that will see the most valuable company ever to join the index. Shares of Tesla were up more than 5 percent in pre-market trade on Tuesday, following the announcement from the index provider, which has decided that Tesla would join the S&P 500 in a single tranche despite its massive market capitalization of US$538 billion before Tuesday's open. Analysts expect…
