Every company missing from free S&P 500 data, and what happened to it.

Download a free list of S&P 500 members from a few years back and the names that were acquired, taken private, or went bankrupt are simply absent. Nothing marks the hole, so a backtest built on that list quietly tests only the survivors and reports their returns as the index's. This page fills the holes: 143 tickers, the actual fate of each one, the date it stopped trading, and a primary source for every single row.

What is in each row

ticker, exit_type, acquirer_or_note (who bought it or what it became), exit_year, exit_date (the last day it traded under that ticker), source_url, verified, ticker_recycled, and a notes line recording what the source actually says. Range covered: 2010 to 2026.

How the names leave

Most of the missing names are not failures. They were bought at a premium, so a survivors-only backtest usually drops the good outcomes as well as the bad ones. That is why the direction of survivorship error is not predictable from theory: it depends on which names your source lost.

The trap that survives a careful join

14 of these tickers were later used by a different issuer. Join old prices to new prices on ticker alone and you can splice two unrelated companies into one continuous series with no warning anywhere in the data: ALTR, BMC, CA, COL, CPWR, EP, FRX, LSI, MI, PGN, PLL, SAI, STR, XL. "Reused" here means strictly that: the same letters appeared later under a different issuer. It does not claim the ticker belongs to that other company today.

The registry

download the registry (csv) · repo and revision history · point-in-time membership dataset

How it was verified

Every row was checked against a primary document and the note records what that document says: 38 rows rest on SEC filings, the rest on company press releases or exchange notices. Where a source had rotted, it was replaced with the filing rather than left as a dead link, and where a host blocks automated fetches the page was confirmed in a browser instead of trusting a script's status code.

Two honest limits. First, this is the set of names that go missing from the free membership sources being probed, not the complete set of every S&P 500 change ever; it grows as more vintages are compared. Second, an exit date is the last day the ticker traded, which for a merger closing intraday is the day of the close.

What to do with it

• Take your own universe file, anti-join it against this list, and count how many exits your source silently dropped. That number is the size of your survivorship hole, measured rather than assumed.
• Before joining price histories on ticker, check the reused list. A splice there is invisible in returns and fatal in a backtest.
• If your data vendor claims point-in-time membership, ask them what happened to a handful of these tickers. The answers separate a real PIT panel from a current-members list.

The rules this page runs on

Built while auditing backtests for survivorship damage; this is the reference list that work needed. The rest of the record: the audit practice · the graveyard · the auction ledger. Generated 2026-08-17 from registry_seed.csv.