Sempre WP sulla volatilità indotta dall'algorithmic trading Solo il 10% delle transazioni nascono da scelte umane. <https://www.washingtonpost.com/news/posteverything/wp/2018/02/07/machines-ca...> [] JPMorgan recently estimated that only 10 percent of stocks are now traded daily by individuals making active choices about what to buy or sell. That figure may be low, but we do know that a large portion of all stocks are owned in relatively new investment vehicles called Exchange-Traded Funds (ETFs) that represent a passive basket of stocks, and that a number of hedge funds are comprised of tens of billions of dollars investing not just in those ETFs, but in derivatives (instruments such as options or futures) that are structured to generate double or triple the returns of those ETFs, or the inverse. Most days, all those baskets and derivatives cancel each other out. But they sit there waiting for days when activity accelerates, pegged to programs that buy and sell based on how quickly prices are moving. The result is a market that is often placid but can take a slight wind and turn it into a selling vortex and then reverse direction and become a buying hurricane.[]