Top Contributors
LIFTED THE INDEXBiggest Drags
PULLED THE INDEX DOWNSector Performance
DAILY % CHANGEMarketLens AI Summary
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Weekly Market View
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Companies
Research pages for the S&P 500's largest constituents — the companies that drive most of the index's daily movement.
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Recent News
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Research
Weekly insights, sector analysis, and plain-English education from the MarketLens team.
The ten largest companies now account for over a third of the S&P 500. Here's why that amplifies daily swings.
Crude prices have drifted lower, and the energy sector has followed. We break down the drivers.
A look back at the sectors, companies, and days that defined the first half of 2026.
An index of 500 of the largest U.S. companies, weighted by size. It's the most common shorthand for "the market."
The index is weighted by market value. A 1% move in Apple affects the index far more than a 1% move in a small company.
A group of companies in similar businesses — like Technology or Energy. Sector moves show which parts of the economy led the day.
Methodology
How MarketLens turns raw market data into daily explanations.
How contributors are calculated
Each company's contribution equals its daily price change multiplied by its weight in the index. A large company moving 1% can contribute more to the S&P 500 than a small company moving 5%. We rank companies by this contribution in index points — not by percentage move alone — to show what actually moved the market.
How sector performance is measured
Sectors follow the GICS classification standard. Each sector's daily change is the market-cap-weighted average of its member companies' returns, so larger companies influence their sector's number more — mirroring how the index itself works.
How AI summaries are generated
After each market close, our system feeds the day's contribution rankings, sector performance, and notable moves to a language model, which drafts two versions: a professional summary and a plain-English explanation. Summaries describe what happened — they never predict or recommend. Data is refreshed once daily at 4:15 PM ET.
About MarketLens
Every day the market moves, and most people never find out why.
Professional investors have research terminals that explain each day's action. Everyday investors get a headline number and little else. MarketLens closes that gap: a free, public platform that shows exactly which companies and sectors moved the S&P 500 — and explains it in language anyone can understand.
We believe understanding the market shouldn't require a $25,000-a-year terminal. Just clear data, honest methodology, and explanations written for humans.
This dashboard provides a simplified overview of S&P 500 market performance, company data, and daily market movements using financial data APIs. Data reflects the regular trading session close and is updated once daily after market close.