Microsoft, Alphabet and Amazon — 15% of the S&P 500 — All Report Earnings This Week
Microsoft, Alphabet and Amazon together account for roughly 15% of the S&P 500, and their back-to-back earnings reports on October 28 and 29 represent the index's biggest scheduled test remaining in 2026.
Three of the S&P 500's five largest companies — Microsoft, Alphabet and Amazon — will release quarterly results within two days of each other this week. Microsoft and Alphabet are set to report on Wednesday, October 28, with Amazon following on Thursday, October 29.
All three have trailed the broader index in 2026. The S&P 500 has gained around 12% this year, yet Microsoft is up only about 8%, Amazon roughly 7%, and Alphabet about 2% based on its Class A shares. Combined, the three have added only about one percentage point to the index's 12% rise — far less than Apple and Nvidia, which contributed roughly three points between them despite similar overall weighting.
At the end of 2025, Microsoft, Amazon and both Alphabet share classes accounted for about 15.6% of Vanguard's S&P 500 index fund. That figure has since slipped to around 15%, while Apple and Nvidia have climbed to about 15.5% of the index.
Each of the three stocks has moved 10% or more after at least one quarterly report this year. Microsoft fell about 10% after its fiscal second-quarter report in January, then jumped roughly 16% following its fiscal fourth-quarter report in July. Alphabet's Class A shares rose about 10% after first-quarter results in April before dropping around 7% after second-quarter results in July. Amazon slid about 6% after its fourth-quarter report in February, then soared about 15% when it reported in July.
For someone holding $10,000 in an S&P 500 fund, roughly $1,500 sits in these three stocks. A repeat of their July reactions would add about $110 to that fund — just over 1% — while a repeat of their January and February moves would subtract around $80.
