People wearing face masks are seen inside a Tesla showroom at a shopping mall in Wuhan, Hubei province, the epicentre of China’s coronavirus disease (COVID-19) outbreak, March 30, 2020.Aly Song | ReutersShares of Tesla traded more than four times their 30-day average volume on Friday as passive funds bought the stock ahead of Tesla joining the S&P 500. The stock will be added to the benchmark index ahead of Monday’s opening bell, based on prices from Friday’s close.Amid the heightened volume, Tesla shares rose 5.96% on Friday to close at a record high of $695 after swinging between gains and losses during the final hour of trading. During after hours trading the stock slid about 2%.Heightened activity continued after hours, and by 4:45 p.m. ET more than 200 million shares had exchanged hands. This is more than quadruple the stock’s 30-day average volume of 44,946,455, according to FactSet. Friday’s volume puts it in the stock’s top 10 most active trading days.Based on Tesla’s Friday average price of $679.85, more than $131 billion worth of stock changed hands.Ahead of Friday’s session, S&P Dow Jones Indices estimated that approximately 129.9 million shares of Tesla would need to be purchased by index fund managers, worth more than $85 billion.However, investors who unofficially track the S&P 500 also needed to buy the stock, which some estimated would lead to purchase activity 50% to 100% above estimates.- CNBC’s Robert Hum contributed reporting.Subscribe to CNBC PRO for exclusive insights and analysis, and live business day programming from around the world.