About the data

• SEC insider transactions data setsForms 3, 4 and 5: every director and officer, with their titles and open-market trades
• SEC Form 13F data setsInstitutional holdings, latest quarter (30 Jun 2026)
• SEC XBRL financial dataShares outstanding, with their history since 2008, and annual revenue
• Yahoo FinanceDaily and weekly closing prices, for market cap
• Wikipedia: List of S&P 500 companiesThe members, their sectors, headquarters and founding years, collected daily with Kadoa
• Congress trading monitorStock trades members of Congress and senior officials disclosed to the House, the Senate and the OGE
• US layoffs trackerWARN layoff notices filed with state labor agencies
• companiesmarketcap.comEmployee counts, collected weekly with Kadoa, until every 10-K figure is in

Market cap is the shares outstanding times the closing price on 23 Oct 2026. It counts every listed class of common stock and classes that convert into it, such as Berkshire Hathaway's class A. It also counts partnership units that convert one for one into listed shares, as at Interactive Brokers, Blackstone and Charter. REIT operating partnership units are left out.

Shares the company or a subsidiary holds itself, such as PG&E's and Accenture's, and shares in Lilly's employee benefit trust are not counted. After a merger, the share count comes from the closing 8-K until the next quarterly report.

S&P weights the index by float, the shares available to trade, so a company's share of the combined value here differs slightly from its official index weight.

The weekly history multiplies each week's last close by the shares the company had most recently reported, adjusted for stock splits. It covers today's members only, from their first week of trading, so companies that left the index since 2008 are missing and totals for December 2008 cover today's members only. Companies whose share history starts in mid-2009 use that first count for the weeks before.

Revenue is the latest full fiscal year a company reported in XBRL, so fiscal years end on different dates. For banks, revenue is net interest income plus fees and other income. Price to sales is market cap divided by that revenue. It says little for banks, insurers and REITs, which are usually valued on book value or funds from operations.

When a company's newest annual report could not be read yet, the page shows the year the revenue comes from and says so.

Revenue is missing where a company has not filed an annual report yet, such as a recent spin-off, or where we have not yet matched its filings; the page says which.

Employees is the latest count from companiesmarketcap.com until each company's 10-K figure is in. Companies with no count show a dash and are left out of totals and the workforce chart.

Not every company counts the same people. A franchisor counts the staff at its own locations, not the people who work for franchisees. A REIT whose buildings are run by outside operators counts only its corporate team. Company pages flag the sub-industries where this is common.

Market cap per employee divides market cap by that headcount. It measures how much the market values each person on the payroll, not what they earn or produce, and it is not comparable where the count leaves most workers out.

Everyone who files Forms 3, 4 or 5 as a director or officer of an S&P 500 company. Major shareholders who are neither are left out.

A role is dropped when the person has filed nothing for that company in the 12 months up to the newest filing in the data. People who left drop out within a year, but so do directors who did not trade or receive stock in that time, which is why some boards look small: Berkshire Hathaway shows a few of its directors. Company pages say how many directors filed, not how many sit on the board.

Board lists from each company's proxy statement (DEF 14A), with tenure, independence and committees, are being collected. Until they are in, boards come from insider filings only.

The SEC publishes these filings in quarterly data sets, so the newest roles and trades can be up to three months old. The latest filings in this version are from 30 Sep 2026.

People are matched by the SEC ID on their filings, so two people with the same name stay apart and one person filing under two spellings stays one.

Names are shown as filed, turned from LAST FIRST into First Last. A few compound surnames may come out in the wrong order.

Titles are as filed. When a filing says only "See Remarks", the title is taken from the remarks; failing that, the person is listed as Director or Officer.

Insider trades are the open-market buys and sales (Form 4 codes P and S) of directors and officers in the 12 months to the newest filing. Grants, option exercises, shares withheld for tax and gifts are left out. A person's trades on one day are added up, and their value is shares times the price filed.

Trades by members of Congress and officials are those disclosed in the three years to the latest filing, under any of the company's share classes. Amounts are the ranges the filings give. Exchanges and the company's bonds are left out.

A WARN notice counts for a company when the employer it names is the company itself, by its own name or its SEC name. Notices from subsidiaries filing under other names, such as Google for Alphabet, are not matched, so some companies show fewer notices than they filed.

Two companies are linked when the same person holds a role at both, as director or officer. A company's connections are the other S&P 500 companies it is linked to; they count companies, not people.

A company and its former parent often share people for a while after a spin-off. Those links are marked on the company pages and the network.

A holder's stake is the shares it reported on Form 13F divided by the company's shares outstanding on the report date. For companies with several share classes, each class is weighted by its value, so the stake is a share of the whole company. Where a company has exchangeable units, the stake is of the listed stock only. Fund groups that file as several entities count as one holder.

Fund groups such as Vanguard hold these shares for the investors in their funds. 13F filings cover managers with over $100 million in US stocks and are filed 45 days after each quarter, so holdings are a quarter old when they appear.

The S&P 500 list is checked daily, employee counts weekly and prices daily. Insider filings are published by the SEC each quarter, and 13F holdings each quarter about 45 days after it ends.