US stock index constituents

Each index page names every company in that index, its weight, and the date the list was reported. The indexes covered are S&P 500, S&P MidCap 400, S&P SmallCap 600, Nasdaq-100, Russell 1000, Russell 2000, Dow Jones Industrial Average. Each list can also be downloaded as a CSV file, and the five index families with published entry rules also carry a page applying those rules to every company we track.

The lists are ranked by weight and rendered in full rather than paged, because these are reference tables people search inside the page.

Every constituent list on Equibles is a tracking fund's own disclosed holdings. A fund that fully replicates an index holds each of the index's companies in index proportion, and a US fund has to disclose what it holds: every quarter in an SEC Form N-PORT filing, and, for most exchange-traded funds, every day in a holdings file published on the fund's own site. Reading the fund is what makes these lists publishable without licensing an index provider's feed, and it is why the figures beside each company are the fund's figures.

The two sources answer different questions. A daily holdings file is fresh, so it dates a change to the day it appeared. An N-PORT filing is quarterly and slower, but it is a filed document with an accession number, so it can be cited and checked by anyone. Both are kept, both are shown, and the published list is the freshest complete one.

A list is published only when it is complete. Each stored snapshot records how many holdings arrived against how many the filing itself reported, and a snapshot short of its own reported count is kept but never published and never compared against another. This is the failure worth guarding against: a list narrowed by our own coverage still looks like a full index, and comparing two narrowed lists manufactures additions and deletions that never happened.

Companies are matched to their pages by identifier and never by name. The order is the company's CUSIP, then an ISIN learned for that company, then the CUSIP embedded inside a US or Canadian ISIN, then the ticker the fund itself stated. A row that matches nothing is kept on the list under the name the fund reported rather than dropped, because dropping it would quietly shorten the index.

Additions and deletions here are derived, not announced. Two consecutive lists from the same fund are compared, so every change is dated to the window between them and both ends of that window are shown. A daily holdings file narrows a change to a single day; a quarterly filing narrows it only to the quarter. Where several funds track one index, the same change is recorded once per fund and collapsed into one event for reading, and the narrowest window wins.

Composition refreshes as its sources do: daily for an index whose fund publishes a daily holdings file, and each quarter as N-PORT filings arrive for the rest. The date at the top of each list is the date the fund reported it, not the date we fetched it.

None of this is official index data. A tracking fund follows its index closely and is not identical to it: it can hold a company a day or two before or after the index does, it holds cash the index does not, and its weights are its own. Where the two differ, the index provider is right and this page is a close reading of a fund.