Nvidia stock accounts for more than a third of the S&P 500’s gains this year—and it’s a big risk for investors, top economist says FortuneAs Nvidia soars, the stock market’s deflated laggards spark concern MarketWatchI’m Not Saying Things Aren’t Crazy The Irrelevant InvestorNvidia alone accounts for more than a third of the S&P 500’s gains this year—and it’s a big risk for investors, top economist warns Yahoo FinanceHere’s Why The Economy Is Not As Strong As It Seems TheStreet