ClinicalTrials.gov by the numbers: 589K studies and a 58% Phase 3 results gap

ClinicalTrials.gov is the world's largest public clinical-research registry, and its size is now its defining feature. The full extract holds 588,992 registered studies. Of those, 449,454 (76.3%) are interventional, 137,513 (23.3%) are observational, and 1,052 are expanded-access programs for patients who cannot enroll in a trial. Academic and government sponsors outnumber industry sponsors more than three to one — but industry concentrates its spending where it matters commercially, running 49.8% of all Phase 3 trials.

This analysis processes the full ClinicalTrials.gov study extract dated June 10, 2026. Every count below is computed from the registry's own fields: study type, phase, recruitment status, sponsor class, lead sponsor, conditions, intervention type, enrollment, and the results-posted flag. The registry captures what sponsors and investigators choose to report; it does not capture trial quality or unpublished data held outside the system.

Study type: three-quarters interventional, a quarter observational

Interventional trials — studies in which investigators assign a drug, device, biologic, or behavioral intervention to participants — account for 76% of the registry. Observational studies, which track outcomes without assigning an intervention, make up 23%. Expanded-access (compassionate-use) programs are a small but operationally important category at just over 1,000 records, because each one represents a manufacturer's controlled decision to supply an unapproved therapy outside a trial.

Sponsorship: academia runs the volume, industry runs the registrational pipeline

Academic, hospital, and nonprofit sponsors ("Other") run 71% of all registered studies. Industry sponsors — 130,133 studies — account for 22%. NIH sponsors just 2%. Read naively, this suggests the registry is dominated by academic research. It is not. The share inverts as trials move toward registration.

Phase 3 is where industry takes over

Across the full registry, industry sponsors 22% of studies. Among Phase 3 trials — the registrational studies that produce the evidence used in FDA, EMA, and payer decisions — industry sponsors 49.8%, a near-majority. Academic sponsors run the bulk of early-phase and exploratory work; industry concentrates its registry footprint on the trials designed to change a label. For market access teams, this is the practical reason Phase 3 readouts and postmarketing commitments move share prices while earlier-phase failures often do not: industry only counts a trial in Phase 3 when it intends to file on it.

Phase distribution

Phase counts above include studies that span more than one phase (for example, a trial listed as Phase 2/3 contributes to both Phase 2 and Phase 3). Roughly 369,000 studies carry no phase assignment ("not applicable" or blank), dominated by observational research and device and behavioral studies that do not use drug-development phasing. Among phased interventional trials, Phase 2 is the largest bucket at 88,790, followed by Phase 1 at 64,682 and Phase 3 at 49,220. Phase 4 — the postmarket studies that often satisfy a postmarketing requirement or expand a label — accounts for 35,317.

Status: 55% completed, 11% recruiting, and a 9% failure pile

Just over half the registry — 321,741 studies — is completed. 119,697 studies (20.3%) are currently live in some active recruitment or enrollment state, including an estimated 7,736 Phase 3 trials. The two failure categories are operationally distinct and worth separating. Terminated trials (33,742) began enrolling and were stopped early. Withdrawn trials (16,453) were registered and never enrolled a single participant. Together they are 50,195 studies (8.5%) — roughly one in twelve registered studies that did not reach completion.

"Unknown status" is its own problem: 93,613 studies (15.9%) have a status the responsible party has not updated, meaning the registry cannot say whether they are still running, finished, or abandoned.

Why trials die: accrual, not science

When a terminated trial records a reason, the reason is usually that nobody enrolled.

Of the 30,225 terminated trials with a documented stop reason, 13,089 (43%) cite an accrual problem — slow accrual, low enrollment, lack of recruitment, or a close variant. Funding problems account for roughly 7%. Adverse events or lack of efficacy — the failure modes the public associates with clinical research — are a minority of stated terminations. The dominant reason a trial ends early is operational: the site could not find, consent, and retain participants fast enough. For launch teams evaluating a competitor's still-recruiting Phase 3, slow accrual is the single most useful early signal that a PDUFA date may slip.

The results-reporting gap

ClinicalTrials.gov is not only a registry; under FDAAA Section 801 and the 2016 HHS Final Rule (42 CFR Part 11), applicable clinical trials of FDA-approved products are legally required to post summary results within one year of their primary completion date, with civil penalties up to $10,000 per day for non-compliance. The data shows the requirement is honored in the breach.

Results posted among completed interventional trials, by phase

Even at Phase 3 — where the legal reporting obligation is clearest and the evidence is most consequential — only 41.8% of completed interventional trials have results posted to the registry. That is 17,237 completed Phase 3 interventional trials with no results visible in the public record (58% of the total). Phase 4, where results often anchor a postmarketing requirement or label expansion, posts at just 32%. These registry-wide rates align with independent compliance research. A September 2025 sponsor-level analysis of 10,605 applicable clinical trials across 257 sponsors found an overall 12-month compliance rate of just 37.2%, with a stark split by sponsor type: industry sponsors averaged 73.7%, NIH sponsors 71.0%, and academic sponsors only 25.5%. The top-performing sponsors across all categories exceeded 90% compliance. In other words, the aggregate registry gap is driven by academic and small sponsors — industry is largely compliant, which sharpens rather than softens the point: where results are missing from an industry-sponsored Phase 3, the absence is more likely to reflect a strategic non-disclosure than a reporting failure.

For evidence and market access teams, the implication is twofold. First, the absence of a posted result does not mean a trial failed — most unreported completed trials are simply out of compliance with FDAAA 801. Second, a sponsor that does post timely results has a concrete transparency signal to use in payer dossiers and AMCP submissions, because most of its peers will not.

Growth: a registry that quadrupled, then plateaued

The registry grew roughly fourfold from 2005 (9,347 studies started) through 2021 (38,425), then plateaued at approximately 38,000–39,000 new studies per year from 2021 through 2025. The plateau coincides with the maturation of FDAAA 801 reporting and the post-pandemic normalization of trial volume after the 2020–2021 surge.

Where the research is concentrated: conditions and interventions

Top conditions studied

"Healthy" — healthy-volunteer pharmacology and Phase 1 studies — is the single largest condition bucket at 10,989. The therapeutic leaders are oncology (breast, prostate, colorectal, lung) and cardiometabolic disease. Obesity at 7,453 reflects the GLP-1 and incretin trial boom and now outranks most traditional disease categories; this registry snapshot is the clearest public record of how much competitive trial capacity obesity now absorbs.

Intervention types

Drug interventions dominate at 208,555, followed by devices and behavioral interventions. Biological interventions — the category that contains monoclonal antibodies, cell therapies, and gene therapies — account for 29,533, a figure that has grown with the cell-and-gene and ADC pipelines and remains far smaller than the small-molecule drug category.

Who runs the most trials: the industry top 15

GlaxoSmithKline (3,600), AstraZeneca (3,438), and Pfizer (3,278) lead the registry by number of industry-sponsored studies. Novo Nordisk's count (1,366) is lower in raw volume than its commercial weight would suggest because the incretin leader's pipeline density is concentrated in a few large, late-phase obesity and cardiometabolic programs rather than a broad early-phase footprint. The median industry-sponsored interventional trial enrolls 60 participants; the distribution has a long right tail, with 1,940 interventional trials enrolling 10,000 or more participants.

What this means for pipeline and access teams

1. Read the registry as a competitive-intelligence layer, not just a transparency layer. Phase 3 status, accrual velocity, and the reason a competitor's trial terminated are all in the public record. A competitor Phase 3 still recruiting 18 months after its posted start is a leading indicator of a PDUFA slip; a terminated Phase 3 with an accrual reason tells you the asset may come back with a redesigned protocol and a new timeline.

2. Industry's Phase 3 concentration is the registry's commercial signal. A sponsor only lists a trial in Phase 3 when it intends to file on it. The 49.8% industry share of Phase 3 trials — versus 22% across the whole registry — means the registrational pipeline is roughly half industry-owned, and that is where late-phase readouts, advisory committees, and label changes will cluster.

3. The results-reporting gap is a payer-evidence risk and an opportunity. With 58% of completed Phase 3 interventional trials posting no results, payers cannot assume a missing registry result means a trial failed. Sponsors that post timely, complete results satisfy FDAAA 801 and gain a credibility edge in evidence reviews, while sponsors that do not post leave payers and competitors to infer outcomes from silence.

4. Accrual is the dominant operational risk, not safety or efficacy. 43% of terminated trials cite an enrollment problem. For launch and CRO-strategy teams, site selection, patient-finding infrastructure, and protocol complexity are larger determinants of whether a trial completes than the underlying science.

5. Obesity and oncology now define the competitive trial landscape. Obesity is the third-largest condition bucket in the registry, behind only healthy volunteers and breast cancer. The volume of incretin and obesity trials is a structural feature of the next several years of readouts, and it will continue to crowd late-phase capacity in cardiometabolic medicine.

Sources

• ClinicalTrials.gov, full study extract, June 10, 2026 (588,992 studies). Analysis by PharmaDossier, run date 2026-06-13. https://clinicaltrials.gov/
• NIH, "FDAAA 801 and the Final Rule (42 CFR Part 11): Clinical Trial Registration and Results Information Submission." https://grants.nih.gov/policy-and-compliance/policy-topics/clinical-trials/reporting/understanding
• ClinicalTrials.gov, "Reporting Results" and FDAAA 801 violation policy. https://clinicaltrials.gov/policy/reporting-requirements
• Mughal Z, Fu R, Luechtefeld T, et al. "Compliance with Results Reporting at ClinicalTrials.gov Before and After the 2017 FDAAA Final Rule: A Comparative Analysis." Journal of Applied Public Health, January 30, 2025. 12-month reporting rates 8.3% to 23.2%; 36-month rates 40.8% to 49.2%. https://publichealth.realclearjournals.org/research-articles/2025/01/compliance-with-results-reporting-at-clinicaltrials-gov-before-and-after-the-2017-fdaaa-final-rule-a-comparative-analysis
• "Sponsor-Level Compliance with ClinicalTrials.gov Reporting Requirements: A Comprehensive Analysis." Journal of Applied Public Health, September 10, 2025 — 257 sponsors, 10,605 applicable clinical trials (2017–2023); overall 12-month compliance 37.2%; industry 73.7%, NIH 71.0%, academic 25.5%. https://publichealth.realclearjournals.org/research-articles/2025/09/sponsor-level-compliance-with-clinicaltrials-gov-reporting-requirements-a-comprehensive-analysis
• National Library of Medicine, "ClinicalTrials.gov: A 25-Year Journey to a Half-Million Registered Studies," April 2, 2025. https://nlmdirector.nlm.nih.gov/2025/04/02/clinicaltrials-gov-a-25-year-journey-to-a-half-million-registered-studies
• Anderson ML, Chiswell K, Peterson ED, et al. "Compliance with Results Reporting at ClinicalTrials.gov." New England Journal of Medicine / PMC4508873 — industry sponsors report at higher rates than NIH and academic sponsors. https://pmc.ncbi.nlm.nih.gov/articles/PMC4508873
• DeVito NJ, Bacon S, Goldacre B. "Compliance with legal requirement to report clinical trial results on ClinicalTrials.gov: a cohort study." The Lancet, 2020;395(10221):361-369. https://www.thelancet.com/journals/lancet/article/PIIS0140-6736(19)33220-9