{"fields":[{"file":"sp500_membership_turnover_2004_2025.csv","name":"security_id","description":"Persistfolio's own stable security identifier (`PFHC-` + 10 hex characters). Not a ticker, CUSIP, FIGI or CIK."},{"file":"sp500_membership_turnover_2004_2025.csv","name":"security_name","description":"The latest legal issuer name evidenced during this membership period. A security with two periods can carry two different names."},{"file":"sp500_membership_turnover_2004_2025.csv","name":"name_history","description":"Every distinct name the security carried during membership, oldest first, separated by semicolons."},{"file":"sp500_membership_turnover_2004_2025.csv","name":"membership_start_date","description":"The date this membership period begins, as a reconstructed membership boundary. Not always the index provider’s published effective date - read `start_date_certainty`."},{"file":"sp500_membership_turnover_2004_2025.csv","name":"membership_start_basis","description":"Why the start boundary has this date (same meaning as `start_date_certainty`, in the parent release’s basis vocabulary)."},{"file":"sp500_membership_turnover_2004_2025.csv","name":"start_date_certainty","description":"How certain the start boundary is (values below)."},{"file":"sp500_membership_turnover_2004_2025.csv","name":"index_effective_start_date","description":"The index-effective date the index provider published for this start, where one is evidenced. Blank otherwise - never filled from a corporate, announcement, SEC, roster or trading date."},{"file":"sp500_membership_turnover_2004_2025.csv","name":"start_earliest_known_date","description":"For a start that is only bounded above by a later anchor: the earliest known date (the announcement date), i.e. the lower side of the window."},{"file":"sp500_membership_turnover_2004_2025.csv","name":"membership_start_event_id","description":"The turnover event that began this period. Blank for securities already in the index when coverage opens on 2004-09-30."},{"file":"sp500_membership_turnover_2004_2025.csv","name":"start_event_type","description":"The type of that event (values below). Blank when there is no start event."},{"file":"sp500_membership_turnover_2004_2025.csv","name":"membership_end_date","description":"The date this membership period ends, as a reconstructed membership boundary. Blank if the security was still a member on 2025-09-30."},{"file":"sp500_membership_turnover_2004_2025.csv","name":"membership_end_basis","description":"Why the end boundary has this date (same vocabulary as the start, plus `STILL_ACTIVE_AT_CUTOFF`)."},{"file":"sp500_membership_turnover_2004_2025.csv","name":"end_date_certainty","description":"How certain the end boundary is (values below)."},{"file":"sp500_membership_turnover_2004_2025.csv","name":"index_effective_end_date","description":"As `index_effective_start_date`, for the end of the period."},{"file":"sp500_membership_turnover_2004_2025.csv","name":"end_earliest_known_date","description":"As `start_earliest_known_date`, for the end of the period."},{"file":"sp500_membership_turnover_2004_2025.csv","name":"membership_end_event_id","description":"The turnover event that ended this period. Blank if still a member at the cutoff."},{"file":"sp500_membership_turnover_2004_2025.csv","name":"end_event_type","description":"The type of that event (values below). Blank when there is no end event."},{"file":"sp500_membership_turnover_2004_2025.csv","name":"confidence","description":"HIGH / MEDIUM / REVIEW - Persistfolio’s classification of the evidence behind the events bounding this period (REVIEW: weak evidence or a bounded date)."},{"file":"sp500_membership_turnover_2004_2025.csv","name":"review_status","description":"CLEAR / REVIEW - REVIEW if an event bounding this period carries an open, disclosed review item."},{"file":"sp500_membership_turnover_2004_2025.csv","name":"lineage_relationships","description":"Successor/lineage links from this security that take effect within this period, separated by ` | ` (values below). Blank if none."},{"file":"sp500_membership_turnover_2004_2025.csv","name":"lineage_to_security_ids","description":"The linked (successor) security_id for each link, in the same positions."},{"file":"sp500_membership_turnover_2004_2025.csv","name":"lineage_to_names","description":"The linked security’s name for each link, in the same positions."},{"file":"sp500_membership_turnover_2004_2025.csv","name":"lineage_effective_dates","description":"The effective date of each link, in the same positions."}]}