June 26 : Even by SpaceX standards, Friday is shaping up as an eventful trading session as investment funds tracking Russell indexes prepare to add billions of dollars' worth of Elon Musk's internet and rocket company to their holdings.After a blockbuster initial public offering this month, SpaceX's stock has been on a wild ride, soaring 67 per cent to its June 16 intraday high of $225.64 before tumbling to Thursday's $153 close.The stock remains well above the $135 IPO price as investors assess how to value a company that lost $4.9 billion last year, but that backers expect to dominate the satellite internet, AI and commercial space launch markets that they believe will define the next decade of global infrastructure.FTSE Russell will add SpaceX to its Russell U.S. indexes after Friday's close of trading as part of its semi-annual index reconstitution. That means passively managed exchange-traded funds that track Russell indexes, such as the iShares Russell 1000 ETF, will have to add SpaceX shares to their portfolios. The event will likely take place in a narrow window toward market close on Friday as fund managers attempt to minimize the "tracking error" between their funds' performance and the index that can result if their buy-in price differs from the closing price.