Antitrust Radar
Merger activity observatory

Scenario analysis / observed shares

Merger structure lab

Calculate a hypothetical concentration change from two published participant shares. This is an arithmetic screen, not a claim that a transaction exists or a legal conclusion.

Live scenarioChatGPT+Google Gemini
Delta HHI+1,458.06Post HHI6,262.06
Eligible markets
6
Observed firm-level shares
Observed periods
18
Definition-matched snapshots
Complete HHI screens
17
Baseline and post-merger HHI
Share observations
136
Named, source-labeled rows
Scenario layer

Market, observed period, and two source-labeled participants can change.

Evidence layer

Published shares, baseline HHI, source status, confidence, and definition remain fixed.

Interpretation layer

Numeric conditions are screening inputs, never a standalone liability or outcome claim.

Observed-share scenario

Structure screen

AI assistantsUnited StatesPublic proxyUsage shares100%named share coverageComplete HHIMedium confidence

Digital platforms / 2026

ChatGPT + Google Gemini

2 x 67.13% x 10.86% = 1458.06 HHI points
Numeric condition crossedThe selected shares cross both published Guideline 1 numeric paths.
Baseline HHI
4,804
2026 published anchor
Delta HHI
+1,458.06
Exact 2ab arithmetic
Post-merger HHI
6,262.06
Published baseline + delta
Merged share
77.99%
67.13% + 10.86%
Participant geometryObserved shares, combined only for this scenario
Observed2026
CombinedScenario
ChatGPT + Google Gemini77.99%Microsoft Copilot10.79%Claude5.99%Perplexity5.18%DeepSeek0.05%
Guideline 1 numeric pathsOfficial reference
Guideline 1 HHI threshold planePost-merger HHI is plotted horizontally and the merger-related HHI increase vertically. The published numeric path is above 1,800 post-merger HHI and above 100 delta HHI. The selected scenario plots at post-merger HHI 6262.06 and delta HHI 1458.06.02,5005,0007,50010,00007501,500HHI 1,800Delta 100Post-merger HHIDelta HHI
Merged-firm share path77.99%

Share above 30% and delta HHI above 100: crossed

Evidence contractOpen market profile

The scenario inherits this published boundary

Product
Consumer generative AI assistant usage across StatCounter-tracked assistants
Geography
United States
Measurement
StatCounter all-platform AI chatbot usage share
Denominator
The tracked assistant shares reported by StatCounter for the monthly snapshot

IncludedThe assistants listed in the StatCounter share table

ExcludedAI revenue, total users, enterprise use, model supply, chips, and cloud infrastructure

LimitationThe usage series is a public web-analytics proxy and does not represent the broader AI supply chain or revenue concentration.

Reusable scenario packet

Carry the exact inputs into research

Antitrust Radar, Merger Structure Lab: ChatGPT + Google Gemini in U.S. generative AI assistant usage (2026); observed shares 67.13% and 10.86%; ΔHHI 1458.06; post-merger HHI 6262.06.
JSONCSV

Source custody

AI chatbot market share in United States of America May 2026StatCounter Global Stats2023 Merger Guidelines, Guideline 1U.S. Department of Justice and Federal Trade Commission / December 18, 2023

01This tool combines two observed shares as a research scenario. It does not report an actual transaction, define a legal market, or predict an agency or court outcome.

02The calculation inherits the published public proxy boundary, United States, measurement basis, denominator, and source limitations shown below.

03The post-merger HHI adds the exact share-based delta to the published, rounded baseline HHI; small rounding differences can remain.

04Guideline 1 concentration arithmetic is one screening framework. The Merger Guidelines identify additional fact-specific theories, evidence, and rebuttal considerations.

The JSON and CSV packets preserve the selected shares, arithmetic, thresholds, evidence status, definition contract, sources, citation, and guardrails.

Merger Structure Lab | Antitrust Radar