PEO Services: AI Market Discovery Index

Benchmark Summary

ADP TotalSource leads the PEO Services benchmark with 37.4% valid recommendation coverage in September 2026, ahead of Justworks at 35.6%, a gap of 1.8 percentage points. No brand recorded a significant coverage movement this month relative to August 2026; the month was stable across tracked brands within normal month-to-month variation.

Across the full July to September series, Justworks recorded the largest coverage decline in the category, falling 7.6 percentage points from 43.2% in July 2026 to 35.6% in September 2026. ADP TotalSource also declined beyond normal variation, falling 7.1 percentage points from 44.5% to 37.4%, though it retained the category lead throughout the series. No tracked brand recorded a significant increase in valid recommendation coverage over the same period; on presence rate, Insperity recorded the largest upward movement, appearing in 57.6% of observations in September 2026, up from 48.3% in July 2026, a gain of 9.3 percentage points.

The benchmark began with 790 prompt-surface observations in September 2026 and produced 396 qualified observations after qualification.

Current Benchmark at a Glance

Qualified surface breadth refers to the number of canonical AI/search surface families with at least one qualified observation: ChatGPT, Copilot, Gemini, Perplexity, AI Overviews, and AI Mode. August 2026 sat between the baseline and current month, with 393 qualified observations and ADP TotalSource leading at 41.7% valid recommendation coverage.

For the strategic interpretation of this benchmark, read CiteWorks Studio's analysis of How AI Search Is Recommending PEO Services

Research Scope and Qualification

The public benchmark is narrower than the raw collection universe by design.

Brand-level percentages use the qualified observations as the public denominator, not the raw collection. Link AI Market Discovery Methodology.

Current Brand Standings

How to Read the Standings

• Presence rate: Share of qualified observations where the brand appears in the AI response.
• Valid recommendation coverage: Share of qualified observations where the brand receives a valid recommendation.
• Top-three rate: Share of qualified observations where the brand appears among the top three recommendations.
• Rank-one rate: Share of qualified observations where the brand is the first recommendation.
• Net sentiment: Positive minus negative mentions divided by total mentions, ranging from -1 to 1.

For formulas and denominator rules, see AI Market Discovery Metric Definitions.

Recommendation Coverage Movement

Compared with August 2026, ADP TotalSource moved down 4.3 points to 37.4% in September 2026 and Paychex PEO moved down 3.9 points to 21.0% in September 2026, both within normal month-to-month variation. TriNet moved down 2.5 points to 34.6% over the same period.

Largest Decline: ADP TotalSource

ADP TotalSource recorded the largest significant decline from baseline, falling from 44.5% valid recommendation coverage in July 2026 to 37.4% in September 2026, a drop of 7.1 percentage points. The brand declined in each of the two months since July 2026, moving from 44.5% to 41.7% in August 2026 and then to 37.4% in September 2026. Its rank-one rate fell from 23.5% in July 2026 to 11.9% in September 2026, yet ADP TotalSource nevertheless remained the category leader.

Largest Decline: Justworks

Justworks also declined beyond normal variation from baseline, falling from 43.2% valid recommendation coverage in July 2026 to 35.6% in September 2026, a drop of 7.6 percentage points. The largest single-month move was 7.8 points from July to August 2026. Its rank-one rate moved in the opposite direction over the full series, rising from 8.8% in July 2026 to 14.4% in September 2026.

Category Leader: ADP TotalSource

ADP TotalSource remains the category leader with 37.4% valid recommendation coverage in September 2026, ahead of Justworks by 1.8 percentage points. ADP TotalSource also holds the highest presence rate at 70.5% and the highest top-three rate at 26.8% in September 2026.

Recommendation Placement Snapshot

Coverage alone does not show how prominently a brand is recommended. Among the leading brands, placement varies notably. Justworks shows a stronger rank-one position relative to its overall coverage, while ADP TotalSource leads on top-three placement.

Similar coverage levels can still hide different first-position rates. TriNet's 34.6% coverage came with a 3.0% rank-one rate, while Justworks' 35.6% coverage carried a 14.4% rank-one rate.

Buyer-Intent Distribution

All qualified observations in both months fell into the Brand Recommendation class.

The current public series measures Brand Recommendation discovery only and does not yet contain qualified observations for Pricing & Value or Multi-Brand Comparison queries.

Historical Measurement Record

This is an evergreen benchmark URL. New measurements are added to the same report.

Evidence and Source Layer

The benchmark is built from prompt-level observations that retain the query, AI/search surface, answer, brand outcome, recommendation placement, sentiment, and, where exposed, citations or attributable evidence sources. Source presence is evidence about the information environment. It is not automatically proof that the source caused the recommendation.

Scope Boundaries

This public benchmark does not measure market share, attributable sales, every possible AI response, organic-search ranking, social mention volume, private or sponsored channels, or causality from a metric movement alone. The current dataset cannot answer pricing, value, or head-to-head comparison questions.

About This Benchmark

The LLM Authority Index AI Market Discovery Index tracks how AI-assisted discovery surfaces present brands within a vertical, measuring presence, recommendation coverage, placement, and sentiment across canonical AI/search surface families.

• AI Market Discovery Methodology
• AI Market Discovery Metric Definitions
• AI Market Discovery Research Standards
• Modeled AI Authority Value

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The public industry benchmark shows category-level standings. A company-level Authority Index can go deeper. The public percentage cannot identify the prompts, competitors, or sources causing the result.

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