Big tech vs Nasdaq 100: Microsoft tracked it most, Tesla leastMicrosoft CorporationBATS:MSFTSignalPilotLabsSeven stocks make up a big part of the Nasdaq 100. We measured how closely each one moved with the index from day to day, over the ten years 2016 to 2025. What we measured TradingView daily closes for the Nasdaq 100 and Apple, Microsoft, Nvidia, Amazon, Alphabet, Meta and Tesla (the stocks through TradingView's BATS feed), on the 2,514 days all eight traded. For each stock: the correlation of its daily moves with the index's, how much it moved per 1% of the index (beta), and the share of days both went the same way. What we found Microsoft tracked the Nasdaq 100 most closely: a correlation of 0.86, the same way on 81.5% of days, and about 1% for each 1% of the index. It was the closest of the seven in 7 of the 10 years. Tesla tracked it least: 0.57, the same way on 68.3% of days. It was the furthest in 8 of the 10 years. All seven, the correlation and the beta: Microsoft 0.86 (1.02) Apple 0.81 (1.04) Alphabet 0.79 (1.01) Amazon 0.77 (1.12) Nvidia 0.75 (1.66) Meta 0.70 (1.20) Tesla 0.57 (1.49) Is it luck? Both halves agree on the ends: Microsoft first and Tesla last in 2016 to 2020 and again in 2021 to 2025. And in 10,000 resamples of the days, Apple, the second, never caught Microsoft. One thing moved: Nvidia went from sixth in the first half to second in the second, and in 2025 alone it was the closest of the seven. What to do with it If you watch one stock for the index's daily direction, Microsoft was the closest. Nvidia moved the most per 1% of the index, 1.66%. Tesla followed it least. On the chart Microsoft, daily, 2025, with the Nasdaq 100 drawn over it in blue on its own scale (the left axis). What this does not tell you Which way the index or any of the seven goes next. A correlation is not a cause. Ten years, one data feed. Past data. Observations, not recommendations.