Big Tech Earnings Could Swing S&P 500 Funds This Week

Microsoft, Alphabet, and Amazon, comprising about 15% of the S&P 500, will report quarterly earnings within two days, potentially causing significant moves in index funds. Their reports on Oct. 28-29 are the year's biggest scheduled test for such funds. The three stocks have trailed the index in 2026, with gains of 8%, 7%, and 2% respectively, versus the S&P 500's 12% rise. Apple and Nvidia, together about 14.6% of the index, added roughly 3 percentage points to the gain, while the three laggards contributed only about 1 point. Historically, these stocks have moved 10% or more after earnings reports, which could shift a $10,000 fund by about $80 to $110. The five largest tech stocks now make up about 30% of the index, but their performance has diverged this year, making the outcome uncertain.