Canonical research dossier
Q38 / Defined markets / Share accountingWhich participant-share changes account for the structural movement, and are the denominator and coverage stable across both anchors?
Search engines / Four-participant concentration ratio- 2025
- 99.4%
- prior anchor
- Observed change
- -0.02 pp
- 1 year
- 2026
- 99.4%
- latest anchor
- Current custody
- 1
- source record
Published signal
The observation behind the question
Latest observed anchor versus the immediately preceding observed anchor; intervening years are not estimated.The latest encoded CR4 anchor is lower within this documented market series. The change alone does not identify a cause or establish competitive harm.
This is a within-profile comparison governed by the documented statcounter search engine referral usage share boundary. It is not annualized and should not be compared as a common national series with differently defined markets.Declared empirical track
Share accounting
Reconstruct participant-share movement while checking denominator, coverage, entry, exit, and transaction changes.- Evidence base
- 4 observed anchors / 2023-2026
- Data status
- estimated public
- Confidence
- low
- Metric family
- market-cr4
Evidence to collect
4 declared requests- 01
Firm- or product-level shares at both anchors using the same denominator.
- 02
Share changes attributable to entry, exit, acquisition, divestiture, or organic movement.
- 03
Coverage, missing-participant, and residual-category documentation for each anchor.
- 04
Source methodology showing whether measurement and participant classification stayed stable.
Current source custody
Evidence already attached to the observed signal
Collection requests above remain separate from these published source records.This is a within-profile comparison governed by the documented statcounter search engine referral usage share boundary. It is not annualized and should not be compared as a common national series with differently defined markets.
Research handoffs