Tech stocks are leading the market lower, with AMD Inc. (AMD) and Arista Networks (ANET) under heavy pressure, after the companies reported earnings. While AMD's numbers topped expectations, some investors are taking profits after the stock's strong run this year. Meanwhile, ANET's guidance came in lighter than expected, raising concerns about the A.I. infrastructure build-out. Tom White says the market's concentration risk is a concern, with 40% of the S&P 500's (SPX) gains coming from just 10 names.