Storage Units: AI Market Discovery Index

Benchmark Summary

Extra Space Storage led the Storage Units benchmark in September 2026 with valid recommendation coverage of 28.9%, down from 29.5% in July 2026. Public Storage held second place at 26.6% in September 2026, up from 26.1% in July 2026, a gap of 2.3 points between the two leaders.

No brand moved beyond normal month-to-month variation in September 2026. The largest coverage increase belonged to Prime Storage, which rose to 4.6% in September 2026 from 2.4% in July 2026. The largest coverage decline came from SmartStop, falling to 5.0% in September 2026 from 8.2% in July 2026.

Across the full July-to-September series, movements were mixed. Three brands declined meaningfully from baseline: Life Storage declined from baseline to reach 2.5% in September 2026 from 5.1% in July 2026, with its most recent month-over-month reading ticking up slightly and remaining within normal variation; National Storage Affiliates declined in two straight months to 0.0% from 1.0%; and SmartStop declined in each of the two months since July 2026, reaching 5.0% from 8.2%. Prime Storage was the sole significant riser, climbing in two consecutive months to 4.6% from 2.4%.

The benchmark began with 800 prompt-surface observations in each month and produced 636 qualified observations in September 2026 as the public denominator.

Current Benchmark at a Glance

Qualified surface breadth counts the six canonical AI/search surface families with at least one qualified observation: ChatGPT, Copilot, Gemini, Perplexity, AI Overviews, and AI Mode. All six remained active across the three-month series. August 2026 sat between the baseline and current months, with 627 qualified observations and a leader coverage of 32.2% for Extra Space Storage.

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

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. See the AI Market Discovery Methodology for the full qualification rules.

Current Brand Standings

How to Read the Standings

• Presence rate: share of qualified observations where the brand appears anywhere in the AI answer.
• Valid recommendation coverage: share of qualified observations where the brand appears in a valid recommendation shortlist.
• 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 single first recommendation.
• Net sentiment: positive minus negative mention tone across the brand's mentions, scaled to a 0 to 1 range.

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

Recommendation Coverage Movement

Between August and September 2026, the largest month-over-month moves were Extra Space Storage down 3.3 points to 28.9%, U-Haul down 2.6 points to 12.6%, and CubeSmart down 2.6 points to 21.2%. No brand's month-over-month change exceeded normal variation. Prime Storage rose again from August to September, extending its streak of monthly gains to two.

Largest Increase: Prime Storage

Prime Storage's valid recommendation coverage rose to 4.6% in September 2026, up from 2.4% in July 2026. The brand climbed in each of the two months since baseline. Its top-three rate also improved, reaching 2.0% in September 2026 from 0.7% in July 2026. Presence rose to 10.4% from 7.8% over the same period, though that change stayed within normal variation.

Largest Decline: SmartStop

SmartStop's valid recommendation coverage fell to 5.0% in September 2026 from 8.2% in July 2026, a decline of 3.2 points that held in each of the two months since baseline. The brand's presence rate dropped to 11.3% from 17.2% over the same window. Its top-three rate (2.4%) and rank-one rate (1.3%) were each down modestly but within normal variation.

Extra Space Storage records 28.9% on valid recommendation coverage, while SmartStop stands at 5.0%. The more important issue is what that gap means for SmartStop's recommendation position: even though SmartStop still appears in 11.3% of qualified observations, only 5.0% convert into a valid recommendation shortlist, meaning fewer than half of SmartStop's brand appearances translate into a recommendation at all. Extra Space Storage's rank-one rate of 11.3% also outpaces SmartStop's 1.3%, a first-choice gap that has persisted across the full three-month series alongside SmartStop's ongoing coverage decline. Left unresolved, this pattern indicates SmartStop's shrinking presence is not the only constraint on its standing — the brand is also underconverting the presence it retains, at a moment when its overall visibility is already falling.

Highest-priority diagnostic: Why is SmartStop's presence failing to convert into valid recommendations at a rate comparable to the category leaders, and what is driving the three-month decline in both presence and recommendation coverage?

Other Significant Declines

Life Storage declined to 2.5% in September 2026 from 5.1% in July 2026, a move that exceeded normal variation. The brand's presence rate fell to 6.3% from 11.6% over the same period. National Storage Affiliates fell to 0.0% in September 2026 from 1.0% in July 2026, declining in two straight months and ending with no valid recommendations in the current month.

Recommendation Placement Snapshot

Coverage shows where a brand appears in a shortlist, but placement shows how prominently it is recommended. Among the three leading brands by coverage, first-position rates diverged in September 2026.

Extra Space Storage's rank-one rate fell to 11.3% in September 2026 from 15.5% in July 2026, even as its valid recommendation coverage stayed broadly stable across the period. Public Storage's rank-one rate rose to 6.3% from 4.8%. Similar coverage levels can still hide substantially different first-position rates across brands.

Buyer-Intent Distribution

All qualified observations in July, August, and September 2026 fell into the Brand Recommendation class, which captures discovery and consideration queries where a user seeks a brand to meet a stated need.

The current public series measures Brand Recommendation discovery only. The qualified sample does not yet contain observations in the Pricing & Value or Multi-Brand Comparison classes.

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. It records where brands appear in AI-generated discovery responses across the six canonical surface families.

About This Benchmark

The LLM Authority Index AI Market Discovery Index tracks how often brands appear and are recommended across six major AI and search surface families. It is a neutral, industry-level measurement built from a defined prompt set and a transparent qualification process.

• 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, isolating a single brand's presence, recommendation coverage, placement, and sentiment across AI surfaces with a tailored prompt set.

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