NEW YORK --- Recent advances in artificial intelligence (AI) are fueling optimism over how businesses can operate more productively in the years ahead. They are also providing a big boost to the stock market. The S&P 500's 9% rally this year has been driven by a handful of the index's biggest stocks, a number of which are at the center of the AI frenzy that has spread in the wake of the chatbot sensation ChatGPT. Five stocks -- Microsoft, Google parent Alphabet, Nvidia, Apple, and Meta Platforms -- are responsible for the S&P 500's entire year-to-date return, said Jessica Rabe, co-founder of DataTrek Research. About 25% to 50% of those gains are owed to "the buzz around...Keep on reading: Artificial intelligence gives real boost to US stock market