Elon Musk, head of Tesla, at the Tesla Gigafactory construction site in Grünheide near Berlin, September 3, 2020.Patrick Pleul | picture alliance | Getty ImagesTesla stock reached an all-time high Thursday, briefly trading at $508.61 per share before closing at $499.27.The company’s stock has been on a tear since the S&P Dow Jones Indices announced this week that it will include the carmaker to the benchmark index prior to trading on Monday, Dec. 21. Money managers with funds that track the S&P 500 will need to buy the stock for their portfolios.The stock is currently on track for its best week since the week ending Aug. 21, ahead of its 4-for-1 stock split on Aug. 31.Morgan Stanley also upgraded Tesla to a buy-equivalent overweight rating Wednesday, the first time in years since the company put a buy rating on the stock, sending share prices up.”Tesla is on the verge of a profound model shift from selling cars to generating high margin, recurring software and services revenue,” Morgan Stanley auto analyst Adam Jonas said in a note on Wednesday. The firm upped its price target to $540 from $360.Tesla recently reported its fifth consecutive quarter of profit on third-quarter revenue of $8.77 billion. The company also reported that it delivered 139,300 vehicles during the third quarter, a new record for it. The company’s stock is up more than 490% year to date.CNBC’s Michael Bloom contributed to this report.Subscribe to CNBC on YouTube.