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Evidence requests describe work to collect, not evidence already established.","comparisonHref":"/research/agenda/compare?questions=market-hhi%3Aus-search-engine-usage%2Cmarket-cr4%3Aus-search-engine-usage%2Cmarket-leader-share%3Aus-search-engine-usage","topicIds":["market-structure","digital-platforms"],"topicCodes":["AR-T01","AR-T02"],"sharedTopicIds":["digital-platforms","market-structure"],"sharedSourceIds":["statcounter-search-us-2026"],"sharedMethodIds":[],"sharedEntityIds":["mkt-search"],"sharedMetricIds":[],"sharedEvidenceRequests":[],"comparisonGuardrail":"Question comparisons preserve each signal's exact anchors, unit, universe, method, and source custody. Shared links represent repeated identifiers only. Native values are never placed on one common scale, and overlap counts are inventories rather than scores of similarity, priority, evidentiary quality, competitive harm, causation, or legal significance."},{"id":"market-cr4:us-search-engine-usage","ordinal":38,"question":"Which participant-share changes account for the structural movement, and are the denominator and coverage stable across both anchors?","methodId":"share-accounting","methodLabel":"Share accounting","methodDetail":"Reconstruct participant-share movement while checking denominator, coverage, entry, exit, and transaction changes.","evidenceRequests":["Firm- or product-level shares at both anchors using the same denominator.","Share changes attributable to entry, exit, acquisition, divestiture, or organic movement.","Coverage, missing-participant, and residual-category documentation for each anchor.","Source methodology showing whether measurement and participant classification stayed stable."],"domain":"markets","domainLabel":"Defined markets","entityId":"mkt-search","entityCode":"us-search-engine-usage","entityLabel":"Search engines","metricId":"market-cr4","metricLabel":"Four-participant concentration ratio","unit":"percentage_points","priorPeriod":"2025","priorYear":2025,"priorValue":99.41,"latestPeriod":"2026","latestYear":2026,"latestValue":99.39,"yearsBetween":1,"delta":-0.02,"deltaPercent":0,"direction":"decreased","observation":"Search engines moved from 99.4% in 2025 to 99.4% in 2026 (-0.02 percentage points).","interpretation":"The latest encoded CR4 anchor is lower within this documented market series. The change alone does not identify a cause or establish competitive harm.","comparisonNote":"Latest observed anchor versus the immediately preceding observed anchor; intervening years are not estimated.","evidenceCount":4,"evidenceLabel":"4 observed anchors / 2023-2026","confidenceLevel":"low","dataStatus":"estimated_public","sourceCount":1,"sourceIds":["statcounter-search-us-2026"],"publishers":["StatCounter Global Stats"],"latestSourceAccessDate":"2026-07-17","agendaHref":"/research/agenda?question=market-cr4%3Aus-search-engine-usage#research-agenda-observatory","atlasHref":"/atlas?focus=question%3Amarket-cr4%3Aus-search-engine-usage&layer=research","researchProfileHref":"/research/agenda/market-cr4--us-search-engine-usage","monitorHref":"/economy/monitor?signal=market-cr4%3Aus-search-engine-usage#competition-monitor-console","notebookHref":"/notebooks?recipe=market-evidence","briefingHref":"/research/briefing?signals=market-cr4%3Aus-search-engine-usage&audience=research#competition-briefing-studio","profileHref":"/markets/us-search-engine-usage","explorerHref":"/trends?markets=us-search-engine-usage&metric=cr4","signalGuardrail":"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.","agendaGuardrail":"Agenda questions are derived from published latest-to-prior competition signals and remain attached to their exact metric, periods, universe, and source custody. They are not ranked, scored, or treated as findings of causality, competitive harm, liability, enforcement merit, or research importance. Evidence requests describe work to collect, not evidence already established.","comparisonHref":"/research/agenda/compare?questions=market-hhi%3Aus-search-engine-usage%2Cmarket-cr4%3Aus-search-engine-usage%2Cmarket-leader-share%3Aus-search-engine-usage","topicIds":["market-structure","digital-platforms"],"topicCodes":["AR-T01","AR-T02"],"sharedTopicIds":["digital-platforms","market-structure"],"sharedSourceIds":["statcounter-search-us-2026"],"sharedMethodIds":["share-accounting"],"sharedEntityIds":["mkt-search"],"sharedMetricIds":[],"sharedEvidenceRequests":["Coverage, missing-participant, and residual-category documentation for each anchor.","Firm- or product-level shares at both anchors using the same denominator.","Share changes attributable to entry, exit, acquisition, divestiture, or organic movement.","Source methodology showing whether measurement and participant classification stayed stable."],"comparisonGuardrail":"Question comparisons preserve each signal's exact anchors, unit, universe, method, and source custody. Shared links represent repeated identifiers only. Native values are never placed on one common scale, and overlap counts are inventories rather than scores of similarity, priority, evidentiary quality, competitive harm, causation, or legal significance."},{"id":"market-leader-share:us-search-engine-usage","ordinal":40,"question":"Which participant-share changes account for the structural movement, and are the denominator and coverage stable across both anchors?","methodId":"share-accounting","methodLabel":"Share accounting","methodDetail":"Reconstruct participant-share movement while checking denominator, coverage, entry, exit, and transaction changes.","evidenceRequests":["Firm- or product-level shares at both anchors using the same denominator.","Share changes attributable to entry, exit, acquisition, divestiture, or organic movement.","Coverage, missing-participant, and residual-category documentation for each anchor.","Source methodology showing whether measurement and participant classification stayed stable."],"domain":"markets","domainLabel":"Defined markets","entityId":"mkt-search","entityCode":"us-search-engine-usage","entityLabel":"Search engines","metricId":"market-leader-share","metricLabel":"Leading-participant share","unit":"percentage_points","priorPeriod":"2025","priorYear":2025,"priorValue":86.71,"latestPeriod":"2026","latestYear":2026,"latestValue":85.16,"yearsBetween":1,"delta":-1.55,"deltaPercent":-1.8,"direction":"decreased","observation":"Search engines moved from 86.7% in 2025 to 85.2% in 2026 (-1.55 percentage points).","interpretation":"The latest encoded Leader share anchor is lower within this documented market series. The change alone does not identify a cause or establish competitive harm.","comparisonNote":"Latest observed anchor versus the immediately preceding observed anchor; intervening years are not estimated.","evidenceCount":4,"evidenceLabel":"4 observed anchors / 2023-2026","confidenceLevel":"low","dataStatus":"estimated_public","sourceCount":1,"sourceIds":["statcounter-search-us-2026"],"publishers":["StatCounter Global Stats"],"latestSourceAccessDate":"2026-07-17","agendaHref":"/research/agenda?question=market-leader-share%3Aus-search-engine-usage#research-agenda-observatory","atlasHref":"/atlas?focus=question%3Amarket-leader-share%3Aus-search-engine-usage&layer=research","researchProfileHref":"/research/agenda/market-leader-share--us-search-engine-usage","monitorHref":"/economy/monitor?signal=market-leader-share%3Aus-search-engine-usage#competition-monitor-console","notebookHref":"/notebooks?recipe=market-evidence","briefingHref":"/research/briefing?signals=market-leader-share%3Aus-search-engine-usage&audience=research#competition-briefing-studio","profileHref":"/markets/us-search-engine-usage","explorerHref":"/trends?markets=us-search-engine-usage&metric=leaderShare","signalGuardrail":"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.","agendaGuardrail":"Agenda questions are derived from published latest-to-prior competition signals and remain attached to their exact metric, periods, universe, and source custody. They are not ranked, scored, or treated as findings of causality, competitive harm, liability, enforcement merit, or research importance. Evidence requests describe work to collect, not evidence already established.","comparisonHref":"/research/agenda/compare?questions=market-hhi%3Aus-search-engine-usage%2Cmarket-cr4%3Aus-search-engine-usage%2Cmarket-leader-share%3Aus-search-engine-usage","topicIds":["market-structure","digital-platforms"],"topicCodes":["AR-T01","AR-T02"],"sharedTopicIds":["digital-platforms","market-structure"],"sharedSourceIds":["statcounter-search-us-2026"],"sharedMethodIds":["share-accounting"],"sharedEntityIds":["mkt-search"],"sharedMetricIds":[],"sharedEvidenceRequests":["Coverage, missing-participant, and residual-category documentation for each anchor.","Firm- or product-level shares at both anchors using the same denominator.","Share changes attributable to entry, exit, acquisition, divestiture, or organic movement.","Source methodology showing whether measurement and participant classification stayed stable."],"comparisonGuardrail":"Question comparisons preserve each signal's exact anchors, unit, universe, method, and source custody. Shared links represent repeated identifiers only. Native values are never placed on one common scale, and overlap counts are inventories rather than scores of similarity, priority, evidentiary quality, competitive harm, causation, or legal significance."}]}