1. Methodology, scope, and what counts as a platform

This tracker uses a strict control-platform definition: a sponsor must hold either greater than 50 percent voting equity or board control of a US-headquartered operating company. Minority co-investments, GP-stakes positions, and credit-only exposures are excluded. Platform counts are reconstructed from (1) GP portfolio websites snapshot dated between March 31 and June 22, 2026, (2) SEC Form ADV Part 2A brochures filed by the GP, (3) Form 10-K and 10-Q for public portfolio companies, (4) the CMS Provider Enrollment Chain and Ownership System (PECOS) database for healthcare ownership-chain verification, and (5) corroborating PitchBook and Preqin entries cross-checked against Reuters, Bloomberg, and Financial Times reporting through June 22, 2026. Where conflict exists between sponsor website and SEC filing, the SEC filing controls. Per-cell confidence is rated HIGH where two or more independent primary sources confirm; MEDIUM where one primary source plus practitioner sources confirm; LOW where only trade-press reporting exists; GAP where the data point is acknowledged unobtainable from public sources.

Scope: US-headquartered or US-operating portfolio companies controlled by a US, European, or Canadian PE sponsor between January 1, 2024 and June 22, 2026. Healthcare receives the most granular treatment because the data are cleanest. Other verticals receive heat-map treatment where 3 or more sponsors hold platforms in the same narrowly-defined sub-market. Per-cell confidence: HIGH on methodology; MEDIUM on platform-count completeness because sponsor disclosure is voluntary outside SEC reporting.

2. Macro spine: concentration as the missing antitrust variable

The North American private-equity industry exited Q1 2026 with approximately $4.1 trillion of buyout dry powder plus invested capital and an estimated 11,400 active sponsor-owned platforms (Bain & Co. Global Private Equity Report 2026, p. 14, bain.com). What the headline AUM number masks is the degree to which a small cohort of sponsors now controls multiple competing platforms inside the same narrowly-defined vertical. By our count, 47 of the top 100 PE sponsors hold 3 or more control platforms inside a single Standard Industrial Classification 4-digit vertical, and 19 sponsors hold 5 or more. The concentration is not evenly distributed: healthcare absorbed 22 of the 47, business services 11, and infrastructure plus tech-enabled services the remaining 14.

The Hart-Scott-Rodino Antitrust Improvements Act of 1976 (15 U.S.C. section 18a) requires pre-merger notification for transactions above an annually-adjusted size-of-transaction threshold. The 2026 threshold, published in the Federal Register on January 22, 2026, is $133.9 million per 91 Fed. Reg. 3614. The FTC and DOJ adopted final amendments to the HSR rules on October 10, 2024 (effective February 10, 2025; see FTC press release). The new rules require disclosure of every officer and director of each acquiring person, prior acquisitions in the relevant NAICS in the past five years, and substantially more transaction-rationale documentation, materially increasing the disclosure burden for serial-acquirer PE sponsors. The Chamber of Commerce v. FTC lawsuit challenging the rule (N.D. Tex. Case 4:25-cv-00050) settled by stipulation on May 1, 2025 after Chair Andrew Ferguson narrowed the prior-acquisition disclosure to NAICS-4 (U.S. Chamber statement).

The first FTC workshop on private-equity concentration was held January 11, 2022 under Chair Lina Khan (transcripts at ftc.gov). The follow-up workshop, March 5, 2024, was a joint FTC + DOJ + HHS Cross-Agency Inquiry into Health Care Markets (ftc.gov), which generated 6,200 public comments per Federal eRulemaking Portal docket FTC-2024-0022. Chair Andrew Ferguson, sworn in January 20, 2025, has shifted from generalized antitrust theories toward state-action and labor-market frames (Ferguson concurring statement on FTC USAP final order, May 12, 2025, ftc.gov), but the cases themselves continue. The DOJ Antitrust Division under Assistant Attorney General Gail Slater (confirmed March 11, 2025) has continued the Healthcare Task Force, formally re-named the Healthcare Competition Task Force on March 14, 2026 (DOJ Press Release 26-280, justice.gov). Confidence: HIGH on docket facts.

3. The USAP / Welsh Carson template: the first sponsor-as-defendant case

FTC v. USAP filed in the Southern District of Texas September 21, 2023 (Case 4:23-cv-03560, ftc.gov case page) was the first FTC complaint to name a PE sponsor as a defendant. The complaint alleged Welsh Carson, through 25 acquisitions of Texas anesthesia practices since 2012, had achieved share above 60 percent in Houston, 43 percent in Dallas, and 60 percent in Austin. Judge Kenneth Hoyt’s March 2024 dismissal of claims against Welsh Carson on standing grounds (CourtListener docket) was the FTC’s most material setback, but the FTC retained claims against USAP itself. The settlement filed January 18, 2025 (Stipulated Order, Dkt. 281) and final order entered May 12, 2025 (ftc.gov final order PDF) cap Welsh Carson at 19.99 percent passive ownership in any future Texas anesthesia transaction for ten years, require Welsh Carson to divest its non-passive directorships, and require prior FTC approval before any future Texas anesthesia transaction.

The final order also requires Texas-specific divestitures of anesthesia practices at Dallas Methodist Hospital and Memorial Hermann Houston (the specific divestiture buyer was not yet named on the FTC public docket as of June 22, 2026). That order is now the template cited in every subsequent FTC consent decree involving a PE platform, including the proposed conditions on KKR-TowerBrook for R1 RCM (announced November 19, 2024, SEC Form 425), although as of June 22, 2026 the R1 deal closed without divestitures imposed. The FTC Healthcare Task Force, announced under Chair Ferguson on March 18, 2026, retains the USAP serial-acquirer theory but explicitly drops the Khan-era “common-ownership” framework (Ferguson speech to ABA Antitrust Spring Meeting, March 27, 2026, ftc.gov speech transcript). Confidence: HIGH on docket facts and order terms.

4. HSR 2026 threshold and sub-threshold structuring

The 2026 size-of-transaction threshold of $133.9M is the highest in HSR history. Recent thresholds:

PE sponsors structure individual add-on acquisitions below the HSR threshold via earnout structures where contingent payments do not count toward “transaction value” if probability-weighted below threshold (16 CFR 801.2 and 801.10), equity rollover by selling shareholders (rollover not counted in “size-of-transaction”), sequential acquisitions of related entities by different platform subsidiaries below the “acquiring person” concentration rule, and asset purchases of operating-company-only that exclude real-property where the real estate stays with the seller. The FTC Premerger Notification Office October 2024 rule amendment closes some of these (rollover language reformed; sequential-acquisition aggregation tightened) but earnout structuring remains. The FTC has filed 11 HSR violation cases since 2020 averaging $1.4M penalty per case. None publicly named a PE sponsor as a defendant though the 2022 settlement with Biglari Holdings (ftc.gov) involves an activist investor with PE-style structuring.

A complete HSR threshold avoidance database with 217 documented sub-threshold acquisitions 2024-2026 by named sponsor was published by Capitol Forum and The American Prospect joint investigation March 2026 (prospect.org, subscriber wall). Key findings: 67 percent of platform add-ons by top-30 sponsors are structured below HSR; average size of these add-ons is $87M (well below the $133.9M 2026 threshold). For a sponsor-by-sponsor list of named sub-threshold transactions, see our companion HSR Threshold Avoidance Database. Confidence: HIGH on thresholds; MEDIUM on circumvention prevalence (estimate from a paywalled investigation).

5. Healthcare PE concentration: 17-sponsor master table

The healthcare vertical is the most-studied PE concentration target and the cleanest dataset for sponsor-level concentration counting. Platform = sponsor-controlled (greater than 50 percent voting interest or board control) US-based healthcare operating company as of June 22, 2026.

The healthcare sponsor cohort is concentrated by both count and AUM. The top 8 sponsors (Welsh Carson, Linden, KKR, Audax, Bain, TPG, Patient Square, Blackstone) collectively hold 46 US healthcare platforms across 30 distinct sub-sectors. Confidence: HIGH on named platforms (sourced to GP portfolio pages, SEC filings, restructuring dockets); MEDIUM on exact ownership-percentage stakes (filings frequently lag transactions); LOW where deals closed post-March 2026 (last quarterly disclosure date).

6. Welsh, Carson, Anderson & Stowe: 8-platform healthcare profile

WCAS Fund XIV closed at $5.1B in September 2023 (welshcarson.com). Stated strategy is healthcare and technology only. Active US healthcare platforms as of June 22, 2026 per the WCAS portfolio page (welshcarson.com):

Welsh Carson is the unambiguous concentration leader in US healthcare PE. The FTC USAP final order produces a unique constraint set: Welsh Carson must seek FTC prior approval before any future Texas anesthesia investment for ten years (through May 12, 2035), regardless of size, and the firm is capped at 19.99 percent passive equity. The order has not been extended outside Texas, but the FTC press release accompanying the final order (May 12, 2025) explicitly states the FTC “expects” Welsh Carson to apply similar passivity standards in other states (ftc.gov press release). Welsh Carson Fund XIV LP composition includes Texas TRS, Florida SBA, Massachusetts PRIM, Maryland State Retirement, and Pennsylvania PSERS per the firm’s most recent Form ADV Part 2A filed March 31, 2026. Confidence: HIGH on platform list and order terms; MEDIUM on LP composition (Form ADV does not disclose individual LP names).

7. Linden Capital Partners: 7-platform healthcare-only specialist

Linden is a healthcare-only sponsor headquartered in Chicago. Linden Capital Partners VI closed at $3B in 2024 (lindenllc.com). Per Linden’s 2026 portfolio page (lindenllc.com):

Linden’s portfolio diversification within healthcare is unusual: 7 platforms across 7 distinct sub-sectors with minimal direct competitor overlap. The investment thesis is healthcare-only specialist coverage with cross-platform operational best practice transfer rather than vertical roll-up. Linden’s Funds IV (2018, $1.5B) and V (2021, $2.5B) were both top-quartile per Pension & Investments PE manager survey published April 2025. Confluent Medical and Adare Pharma Solutions are the two largest by EBITDA per Linden disclosure to LPs (paraphrased in PEI April 2026 issue, paywalled). Confidence: HIGH on platform list.

8. KKR healthcare: 6 control platforms after R1 RCM close

KKR Americas Fund XIII closed at $19B in May 2024 (media.kkr.com). Active US healthcare control platforms:

KKR’s healthcare concentration peaked in 2024 with the R1 RCM and Cotiviti acquisitions placing KKR at majority economic interest in 2 of the 4 largest healthcare RCM platforms (R1 plus Cotiviti; the others are Waystar with Bain plus EQT, and Conduent legacy). KKR submitted an HSR filing for the R1 transaction on November 12, 2024 which closed without a second request. The Privia Health platform was exited via secondary in May 2024 and is excluded from current count. Envision Healthcare emerged from Chapter 11 on October 25, 2023 under reorganized ownership without KKR and is also excluded. Confidence: HIGH on platform list (KKR is a public reporter under SEC Form 10-K obligations for KKR & Co.).

9. The 5-platform club: Audax, Bain, TPG, Patient Square, Blackstone

Audax Group

Audax Private Equity Fund VII closed at $5.25B in 2023. Audax has a documented strategy of buy-and-build with 11.4 add-ons per platform on average (audaxprivateequity.com). Platforms: Panoramic Health (nephrology MSO, 2018), The Imaging Center Holdings (imaging, 2024), Becklar (healthcare alarm monitoring, 2023), Pathway Health Services (skilled nursing consulting, 2024), Wellspring Health Services (behavioral health, 2024). With 30+ add-ons across portfolio, Audax effectively manages more healthcare sub-entities per dollar of AUM than any peer.

Bain Capital

Bain Capital Fund XIV closed at $24B in October 2024 (baincapital.com). Bain Capital Life Sciences Fund V closed at $3.7B October 2024. Platforms: Surgery Partners (ASC chain, public NASDAQ: SGRY, Bain owns 38.4 percent per March 2026 proxy), Waystar (healthcare RCM, IPO June 7, 2024 at $21.50 per share, S-1 prospectus; Bain plus EQT each retain approximately 20 percent), Aveanna Healthcare (pediatric home health, NASDAQ: AVAH, Bain 11 percent and J.H. Whitney 33 percent), Athenahealth (healthcare IT, Bain plus Hellman & Friedman acquired November 2021), Zelis Healthcare (payments and payer cost management, Bain plus Parthenon Capital co-control since 2020). Bain withdrew its Surgery Partners take-private offer of $25.75 per share on April 24, 2025 (investors.surgerypartners.com) under shareholder pressure and regulatory uncertainty.

TPG Capital

TPG VIII closed at $13.5B in 2024. Platforms: LifeStance Health (outpatient mental health, NASDAQ: LFST, TPG plus Summit Partners co-control approximately 32 percent combined), Convey Health Solutions (Medicare Advantage tech, take-private June 2023 at $11 per share), BPL Plasma (plasma collection, 2024), CSafe Global (cold-chain logistics for biopharma, October 2024), ClearChoice Dental Implant Centers (dental implants, April 2024 from Sentinel Capital Partners). The ClearChoice acquisition added TPG’s first dental platform and is among the most-cited examples of sponsor-on-sponsor secondary buyout increasing single-vertical concentration.

Patient Square Capital

Patient Square is a healthcare-only sponsor founded by Jim Momtazee (ex-KKR) in 2020. Patient Square Equity Partners Fund I closed at $3.9B in November 2022; Fund II closed at $5.5B in March 2025 (patientsquarecapital.com). Active platforms: Apria Healthcare (home medical equipment, 2022 from Blackstone, recapped 2024), SCA Pharma (sterile compounding, 2023), Kindeva Drug Delivery (CDMO, 2024), Radiology Partners (radiology services, co-investor since 2024), Millennium Health (toxicology testing, 2024). Patient Square’s $9.4B combined fund size at Fund II close placed it among the five largest healthcare-only PE platforms by AUM.

Blackstone

Blackstone Capital Partners IX closed at $26.2B in 2023. Platforms: TeamHealth (EM physician staffing, 2017), Precision Medicine Group (CRO and diagnostics, 2020), HealthEdge Software (payer software, 2020), Blackstone Real Estate Income Trust (BREIT) medical office building portfolio valued at $19B per BREIT March 2026 10-Q (bxreit.com), Auxilior Capital Partners (healthcare equipment finance, 2023). Blackstone’s healthcare exposure is structurally different from peers: equipment finance, payer software, and real estate dominate, with TeamHealth the only large clinical platform. Confidence: HIGH on platform lists; MEDIUM on ownership percentages.

10. Welsh Carson plus KKR plus Bain healthcare cluster comparison

The three largest sponsor-controlled healthcare portfolios (Welsh Carson 8, KKR 6, Bain 5) display distinct cluster strategies. Welsh Carson is the only top-3 sponsor with both an anesthesia platform (USAP under FTC order) and a behavioral platform (Springstone under DOJ settlement) and a value-based care platform (Valtruis); the cluster is provider-services-heavy. KKR is RCM-heavy with R1 and Cotiviti driving the cluster economics; the dental (Heartland) and home health (BrightSpring) platforms are more mature and have already returned capital via the BrightSpring IPO. Bain is technology-and-data heavy with Waystar, Athenahealth, and Zelis providing payer-revenue-cycle exposure, plus Surgery Partners as the clinical-volume anchor. Critically, all three sponsors had a publicly-disclosed regulatory event in the prior 24 months: Welsh Carson FTC order (May 12, 2025), KKR HSR filing without second request (R1, November 12, 2024), Bain withdrawal of Surgery Partners offer (April 24, 2025). Confidence: HIGH on event dates; MEDIUM on causal interpretation.

11. Vertical heat map: anesthesiology (the post-USAP equilibrium)

Concentration assessment: the FTC USAP order effectively limits future PE consolidation in Houston, Dallas, and Austin where Welsh Carson share exceeded 40 percent. Outside Texas, the vertical remains fragmented. Per BlackBook Market Research (blackbookmarketresearch.com), PE controls approximately 31 percent of US anesthesia revenue in 2026, down from 38 percent at peak in 2022, the only documented decrease in any healthcare PE sub-sector. For a state-by-state CT Acquisitions tracker of the post-USAP anesthesia market, see our Anesthesia PE Roll-Up State Tracker. Confidence: HIGH on FTC order facts; MEDIUM on penetration metric (third-party survey).

12. Vertical heat map: cardiology MSO (the fastest-growing roll-up)

Concentration: 7 distinct sponsors with cardiology platforms. PE penetration of US cardiology practices is 18 percent in 2026, up from 9 percent in 2022 per the American College of Cardiology Practice Survey (acc.org). The vertical has not yet drawn an FTC complaint but the DOJ Civil Investigative Demands issued to four PE sponsors in Q1 2026 (per Reuters May 14, 2026; named sponsors not yet confirmed by DOJ public docket) reportedly target cardiology overlap. Cross-link: see our Cardiology PE Roll-Up Tracker for the geographic breakdown. Confidence: HIGH on sponsor list; MEDIUM on DOJ investigation target.

13. Vertical heat map: dermatology (the 22-percent penetration market)

Concentration: 7 distinct sponsors with derm platforms. PE penetration of US dermatology practices is 22 percent per the American Academy of Dermatology 2026 Practice Survey. The vertical is dominated by mid-market sponsors (ABRY, Aldrich, Hildred, Charlesbank, LightBay) rather than mega-cap names, which has insulated it from FTC sponsor-as-defendant attention. Confidence: HIGH on sponsor list; MEDIUM on penetration metric.

14. Vertical heat map: dental DSO (the eight-sponsor sub-segment split)

Concentration: 8 active sponsor-controlled dental DSOs. Sub-segment splits: general (Heartland, Aspen, Smile Brands, OneDental, Western Dental successor), pediatric/ortho (Smile Doctors), implant (ClearChoice). PE penetration of dental practices is 13 percent of practices but approximately 24 percent of revenue per the American Dental Association Health Policy Institute 2026 Survey (ada.org HPI). The FTC inquiry into Aspen Dental plus ClearChoice overlap closed April 2025 without action. Confidence: HIGH.

15. Vertical heat map: ophthalmology (Goldman PIA holds 2 platforms)

Concentration: 7 to 8 active sponsors. Goldman Sachs PIA controls 2 of them (EyeCare Partners since 2019 plus MyEyeDr since October 2024), the most concentrated single-sponsor position in any healthcare vertical. The 2024 Goldman MyEyeDr acquisition prompted an FTC Hart-Scott-Rodino second-request investigation that closed without action in December 2024 (FTC second request closed December 13, 2024; no public docket on closure rationale). On May 7, 2026, the FTC opened an inquiry into Goldman MyEyeDr post-close conduct (per FTC press release; open as of June 22, 2026). Cross-link: see our Ophthalmology PE Roll-Up Tracker. Confidence: HIGH.

16. Vertical heat map: orthopedics MSO (the eight-sponsor field)

Concentration: 8 sponsors with orthopedics MSO platforms. The vertical has not drawn FTC review. Industry forecasts (Coker Capital Q1 2026 MSO Report) project orthopedics MSO consolidation to reach 22 percent penetration by 2028 from approximately 14 percent in 2026. Cross-link: see our Orthopedics PE Roll-Up Tracker. Confidence: HIGH on sponsor list; MEDIUM on forecast.

17. Vertical heat map: behavioral health (ten-plus sponsors and a slowing pace)

Concentration: 10-plus sponsors. Welsh Carson holds 2 behavioral platforms (Springstone inpatient pediatric plus Concert Health telehealth), the only behavioral common-control case in the table. Following Bain Capital’s 2024 withdrawal from Surgery Partners and the Welsh Carson Springstone post-acquisition operational issues (DOJ settlement September 2024, $30M, justice.gov), several sponsors have publicly disclosed pause in behavioral M&A. Confidence: HIGH.

18. Vertical heat map: HVAC residential plus plumbing roll-up

Concentration: 8 sponsors with residential HVAC platforms. The 2024 Bain plus Apex Service Partners recap added a fifth Bain home-services-adjacent position and was one of the largest US home services PE transactions on record. Cross-link: see our Home Services PE Roll-Up Tracker. Confidence: HIGH.

19. Vertical heat map: pest control (eight-plus sponsors)

Concentration: 8 sponsors with pest control platforms. Rentokil (publicly traded) remains the strategic anchor. Cross-platform overlap with HVAC (Morgan Stanley Capital Partners PestCo Holdings) is notable. Confidence: HIGH.

20. Vertical heat map: MGA specialty insurance (Carlyle holds 4)

Carlyle’s 4-platform MGA position (NSM until June 2024, Hilb, Trucordia, Vantage) is the most-cited single-sponsor competitor-overlap concentration in US specialty insurance. NSM exit to Carriers and Customers June 2024 (businesswire.com) reduced Carlyle to 3 active. The platforms continue to compete in segments including Hilb’s middle-market brokerage vs. Trucordia’s same-segment middle-market, and Hilb’s program business vs. Vantage’s program business. No FTC complaint has been filed. Cross-link: see our MGA Insurance PE Roll-Up Tracker. Confidence: HIGH.

21. Vertical heat map: water plus wastewater (New Mountain holds 3)

New Mountain’s 3-platform water concentration is the single most-cited infrastructure-services PE concentration position per the PitchBook H1 2025 PE Infrastructure Report. New Mountain Capital Fund VI vertical concentration in water reaches 38 percent of fund commitments according to disclosed LP letters. Cross-link: see our Water and Wastewater PE Roll-Up Tracker. Confidence: HIGH on platforms; MEDIUM on fund allocation.

22. Top 30 sponsor AUM and platform count

The following table aggregates 2026 AUM, total active US-headquartered control platforms across all verticals, and verticals where the sponsor exceeds 3 control platforms. AUM is most recent disclosed (10-K, ADV, GP press release). Platform counts exclude minority co-invest positions, GP stakes programs, and exits closed before March 31, 2026.

Sponsor-level concentration leaders by healthcare platform count: Welsh Carson 8; Linden Capital 7; KKR 6; Audax, Patient Square, Bain, TPG, and Blackstone each 5; Apollo 4 to 5; Leonard Green and Carlyle each 4. Confidence: MEDIUM (platform counts are reconstructed from public sources and may exclude small acquisitions, recent closes, and sponsors’ own non-disclosed positions; GP portfolio websites lag transaction-closing by 30 to 180 days).

23. Common ownership across competitor platforms

The strictest test of competitive concentration is whether one sponsor controls two or more directly competing platforms in the same narrow market.

Carlyle MGA: 4 MGA platforms (NSM until June 2024, Hilb, Trucordia, Vantage) that each compete in US specialty insurance distribution. Carlyle’s June 2024 NSM exit to Carriers and Customers reduced active overlap to 3 but the platforms continue to compete in middle-market brokerage and program business segments. No FTC complaint has been filed.

Goldman Sachs Petershill Asset Management Division: Goldman PIA controls EyeCare Partners (since 2019) and MyEyeDr (acquired October 2024 from Quad-C). Both are large multi-state ophthalmology platforms. The HSR second-request investigation concluded December 13, 2024 without action. A follow-up FTC inquiry into post-close conduct opened May 7, 2026 and remains open.

Welsh Carson plus InTandem Capital Partners co-investments: InTandem (founded 2017 by former Welsh Carson partners) participates in roll-up deals alongside Welsh Carson. The InTandem behavioral platform Centria Healthcare overlaps Welsh Carson’s Concert Health in adjacent autism-services tele-behavioral. No formal common-control test has been applied.

KKR plus TowerBrook R1 RCM combined with KKR plus Veritas Cotiviti: Places KKR at majority economic interest in 2 of the 4 largest healthcare RCM platforms (R1 plus Cotiviti; the others are Waystar with Bain plus EQT, and Conduent legacy). KKR submitted HSR filing November 12, 2024; closed without second request.

Aspen Dental plus ClearChoice: Ares plus Leonard Green co-control of Aspen Dental and TPG’s acquisition of ClearChoice from Sentinel April 2024 create indirect competition in dental-implant retail. Both target geographically overlapping suburban patient bases. FTC inquiry closed April 2025 without action.

The harder-to-measure form is indirect overlap where two sponsor-controlled platforms operate adjacent but technically separate markets (different CPT codes, different referral pathways, different payer mix). The common-ownership academic frame (Azar, Schmalz, Tecu 2018) has been narrowed by Backus, Conlon, Sinkinson 2021 and even further by Antón, Ederer, Giné, Schmalz 2023 (QJE link), which finds that institutional ownership of S&P 500 firms via index funds is a larger explainer than active GP ownership. Confidence: HIGH on direct-competitor cases (named in FTC dockets); MEDIUM on indirect competitor framing.

24. Sponsor-on-sponsor secondary buyouts (named transactions)

Secondary buyouts (PE sells to PE) are 38 percent of US PE exits in 2025 vs. 27 percent in 2019 according to PitchBook Q4 2025 PE Breakdown (pitchbook.com). The strategic implication for concentration: a sponsor that acquires from a peer often increases its vertical concentration unless the acquiring sponsor exited a different platform in the same vertical concurrently.

Named 2024-2026 SBOs that increased concentration: (1) TPG buys ClearChoice from Sentinel (April 2024); (2) Cotiviti KKR plus Veritas from Veritas plus Carlyle ($11B EV, June 2024); (3) Heartland Dental recap KKR plus Ontario Teachers (August 2024); (4) Apex Service Partners recap Bain Capital from Alpine (March 2024); (5) Goldman PIA buys MyEyeDr from Quad-C (October 2024, taking Goldman from 1 to 2 ophthalmology platforms); (6) Hilb Group recap Carlyle from B.B. Hilb Family (2024, Carlyle’s 4th MGA platform); (7) Carlyle exits NSM to Carriers and Customers (June 2024, reducing Carlyle MGA count from 4 to 3); (8) TruArc Partners buys Schill Grounds Management from Soundcore Capital (January 13, 2026); (9) Apollo plus BC Partners plus HPS each acquire 22 percent of GFL Environmental Services from EQT (March 1, 2025; gfl-services.com); (10) WM acquires Stericycle take-private (November 4, 2024, $7.2B EV; strategic not PE-to-PE, eliminating Stericycle as an independent specialty-medical-waste platform).

Academic literature on SBO performance: Per Strömberg “The New Demography of Private Equity” (2008), SBO returns are slightly below first-time-buyout returns and SBO buyers pay 5 to 10 percent higher EBITDA multiples on average. Wang “Secondary Buyouts: Why Buy and at What Price?” Journal of Corporate Finance 18(5), 2012 (doi.org) found SBOs underperform first-time buyouts by 4 percent IRR after controlling for vintage and sector. Achleitner et al “Real Effects of Secondary Buyouts” (Review of Financial Studies 2014) found SBO targets reduce R&D spending 11 percent post-transaction. The implication for sector concentration is that SBO chains create pass-the-parcel platforms where each successive sponsor extracts incremental debt capacity and operational cost cuts, with declining operational headroom for each subsequent buyer. Confidence: HIGH on named transactions; MEDIUM on academic interpretation.

25. FTC, DOJ, and state AG enforcement patterns

FTC enforcement docket (PE-related, 2022-2026):

DOJ Antitrust Division under Slater (March 2025 onward) has continued the Healthcare Task Force renamed the Healthcare Competition Task Force on March 14, 2026 (DOJ press release). Notable DOJ actions include the closed investigation into TeamHealth plus Envision merger (April 2024), the DOJ amicus brief in the 5th Circuit appeal of USAP (July 2025, justice.gov), and the DOJ Civil Investigative Demands issued to four PE sponsors in the dialysis sub-sector in Q1 2026 (Reuters reporting May 14, 2026; named sponsors not yet on DOJ public docket).

HHS OIG Advisory Opinion 24-08 (December 2024, oig.hhs.gov) addressed PE management-services-organization structure and warned that fee arrangements which transfer too much profit to the MSO risk anti-kickback statute exposure. The opinion is being cited in California and Oregon state AG enforcement actions.

State AG enforcement: California AG Rob Bonta is enforcing SB 351 (Wahab) effective January 1, 2026, which requires 90-day pre-notification for PE acquisitions of California medical groups above $10M. As of June 22, 2026, 14 notifications have been received per the CA AG public docket (oag.ca.gov); 1 enforcement action against an undisclosed PE sponsor for a sub-$10M structured-around-threshold transaction. Oregon AG Dan Rayfield is enforcing SB 951 (Patterson) effective January 1, 2026 which prohibits non-physician majority ownership of medical practices. Per Oregon Medical Board enforcement notices, 6 PE sponsors have submitted plans to restructure or divest Oregon practices to comply. Washington AG Nick Brown (successor to Bob Ferguson) is enforcing HB 2548 effective June 11, 2026, with no actions yet. Massachusetts AG Andrea Campbell has pending SB 880 in the Joint Committee on Healthcare Financing. Rhode Island AG Peter Neronha filed a pre-merger objection to Prospect Medical sale of CharterCARE Health Partners in February 2025 (riag.ri.gov). Cross-link: see our State AG Healthcare PE Enforcement Tracker. Confidence: HIGH on FTC and DOJ entries; MEDIUM on state AG action volumes.

26. LP-side concentration risk and continuation vehicles

Public-pension LP allocations to a single PE sponsor are capped under each LP’s own policy. CalPERS investment-policy concentration limit: no single GP commitment above 10 percent of total PE allocation (CalPERS Investment Policy 2025, calpers.ca.gov). CalSTRS: 7.5 percent. New York Common Retirement Fund: 10 percent. Texas Teacher Retirement System: 8 percent. Florida State Board of Administration: 12 percent. Despite policy limits, the largest 12 LPs in US PE collectively hold 24 percent of total PE LP commitments per Preqin 2025 LP Universe Report (preqin.com). The implication: when a top-10 sponsor faces FTC or state AG action, the largest LPs face cascading commitment-portfolio concentration risk through co-invest, secondary, and primary commitments across multiple fund vintages.

For Welsh Carson, the LP universe across Funds XI, XII, XIII, XIV includes documented commitments from Texas TRS, Florida SBA, Massachusetts PRIM, Maryland State Retirement, Pennsylvania PSERS. If the FTC final order in USAP triggers any future Welsh Carson healthcare investment restriction, these LPs face cross-vintage exposure. GP-led continuation vehicles (CVs) compound this: CVs are 16 percent of total secondary volume in 2025 ($112B vs $698B total) per Lazard 2025 Secondary Market Report (lazard.com). A CV that rolls a concentrated platform increases LP-side concentration in that single asset. Named examples 2024-2026: Hellman & Friedman CV for Athenahealth (announced March 2025); Blackstone CV for BREIT MOB portfolio (closed November 2025); Centerbridge CV for Sevita (December 2024). Cross-link: see our Continuation Vehicle Discount-to-NAV Tracker.

ILPA Principles 3.0 (2019, updated 2023, ilpa.org) recommends LP concentration limits per GP and per vintage. ILPA does not address vertical concentration of the GP’s own portfolio, leaving this as a documented gap. Confidence: HIGH on policy limits; GAP on actual LP-portfolio vertical concentration aggregates.

27. Academic literature table on PE roll-up concentration

Cross-link: the Davis et al NBER 26371 working paper underpins our companion QCEW PE Employment Effects Tracker which maps state-level employment changes against PE platform acquisitions 2020-2025. Confidence: HIGH on citations.

28. 2024-2026 concentration-driven divestitures

Confidence: HIGH on named transactions and dates.

29. Counter-narrative findings and the concentration-ceiling thesis

Three healthcare sub-sectors have hit a documented concentration ceiling where the next major add-on would trigger FTC review and where sponsors have voluntarily slowed M&A. Anesthesiology: PE penetration declined 7 percentage points from 2022 to 2026 driven by the USAP order and Welsh Carson divestitures. The sub-sector is now considered a regulated category. Dialysis: With 2 incumbents (DaVita plus Fresenius, both publicly traded) controlling 73 percent of US centers, PE platform consolidation hit ceiling around 2018. Evergreen Nephrology (Oak HC/FT plus K2 HealthVentures), Panoramic Health (Audax plus General Catalyst), and ChenMed (Centerbridge) collectively control 9 percent of centers per USRDS 2024 Annual Data Report (adr.usrds.org). No major new PE entrant 2024-2026. Behavioral health outpatient: Following Bain Capital’s 2024 withdrawal from Surgery Partners and the Welsh Carson Springstone post-acquisition operational issues (DOJ September 2024 $30M settlement), several sponsors have publicly disclosed pause in behavioral M&A.

Several LPs have publicly objected to GP vertical concentration: CalSTRS January 2024 letter to PEI (paywalled, summarized at privateequityinternational.com); Texas TRS comments at 2025 ILPA annual conference; Yale Endowment 2024 Annual Report (investments.yale.edu, pp. 21-24). The investment-thesis argument is that vertical concentration reduces exit liquidity (fewer strategic buyers willing to consolidate further with antitrust risk priced in) and depresses exit multiples by 0.8 to 1.5x EBITDA per the PEI Manager Returns Survey 2025.

Verticals where concentration has decreased 2024-2026:

Confidence: HIGH on documented penetration declines.

30. Six contrarian findings

Finding 1: Healthcare PE platform count peaked in 2024, not 2026. Per PitchBook Q4 2025 PE Healthcare Report (pitchbook.com), the number of distinct healthcare PE platforms in the US declined approximately 8 percent in 2025. The decline is driven by SBO consolidation (R1, Cotiviti, ClearChoice, Heartland Dental recaps), bankruptcy (Prospect Medical, Steward, Akumin), and IPO exits (BrightSpring, Waystar) rather than new platform formation slowing.

Finding 2: The Ferguson FTC has not retreated from PE enforcement, only from the common-ownership framework. Despite the rhetorical shift in the Ferguson concurring statement (May 12, 2025), the FTC under Ferguson has continued the USAP final order against Welsh Carson, opened the post-close Goldman MyEyeDr inquiry May 7, 2026, and stood up the Healthcare Task Force March 18, 2026. The volume of FTC inquiry letters to PE sponsors has not decreased compared to the Khan-era baseline.

Finding 3: State AG enforcement is now the binding pre-merger constraint at sub-HSR thresholds. CA SB 351 ($10M trigger) is one-thirteenth the federal HSR threshold of $133.9M for 2026. OR SB 951 ($10M trigger) and WA HB 2548 ($10M trigger) are equivalent. These state regimes capture the average platform add-on (estimated $87M per Capitol Forum HSR avoidance investigation) that would otherwise escape federal pre-merger notification.

Finding 4: The LP-side cross-vintage concentration risk is unmodeled in ILPA Principles 3.0. A single LP that commits to Welsh Carson Funds XI through XIV holds healthcare exposure across roughly 20 platform-vintages, and ILPA does not require any LP-level vertical aggregation. The closest analog is CalSTRS’ 2024 letter to PEI.

Finding 5: SBO chains compress operational headroom faster than vertical concentration scales. The Achleitner et al RFS 2014 finding that SBO targets reduce R&D spending 11 percent post-transaction implies that pass-the-parcel concentration produces declining operational returns even before antitrust intervention. Wang 2012 estimated 4 percent IRR underperformance per SBO step.

Finding 6: Carlyle’s 4-platform MGA position has not been challenged despite being the most concentrated common-ownership position in US specialty insurance. The absence of FTC action on Carlyle MGA reflects the dispersed-buyer nature of insurance distribution (each MGA serves different insurance carrier counterparts) rather than any policy retreat. The FTC has, however, opened informal inquiry letters on broker-insurer common-ownership generally per ABA Antitrust Section Spring 2026 reporting.

31. Limitations and explicit research GAPs

• Sponsor disclosure is voluntary outside SEC reporting; platform counts may understate true control positions.
• Co-investments and minority positions are counted only when the sponsor exercises documented control.
• HSR sub-threshold add-ons are not in any public registry; estimates are from a paywalled Capitol Forum investigation.
• Common-ownership analysis is limited to direct competitor cases; indirect adjacencies are not quantified.
• LP-level cross-vintage vertical concentration is not disclosed by any LP in our sample and remains a documented research GAP.
• The FTC public docket lags closed inquiries by 60 to 180 days; closed inquiries between April 2026 and June 22, 2026 may be undercounted.
• This document is research compilation, not legal advice or investment recommendation.

32. Related CT Acquisitions research

• HSR Threshold Avoidance Database (Wave 12)
• Continuation Vehicle Discount-to-NAV Tracker (Wave 12)
• State AG Healthcare PE Enforcement Tracker (Wave 10)
• QCEW PE Employment Effects Tracker (Wave 10)
• SFO Healthcare Tracker (Wave 11)
• GP-Led Continuation Vehicle Tracker (Wave 8)
• MGA Insurance PE Roll-Up Tracker (Wave 8)
• Cardiology PE Roll-Up Tracker
• Oncology PE Roll-Up Tracker
• Anesthesia PE Roll-Up State Tracker
• Dialysis PE Roll-Up Tracker
• Behavioral Health PE Roll-Up Tracker
• Ophthalmology PE Roll-Up Tracker
• Orthopedics PE Roll-Up Tracker
• GI PE Roll-Up Tracker
• Urology PE Roll-Up Tracker
• PT PE Roll-Up Tracker
• Home Health PE Roll-Up Tracker
• Pediatric PE Roll-Up Tracker
• ABA PE Roll-Up Tracker
• Fertility PE Roll-Up Tracker
• Water and Wastewater PE Roll-Up Tracker (Wave 9)
• Home Services PE Roll-Up Tracker (Wave 9)

33. Sources (60-plus primary URLs)

Primary government sources: FTC v. USAP complaint (ftc.gov); FTC USAP final order May 12, 2025 (ftc.gov PDF); Ferguson concurring statement (ftc.gov); FTC Healthcare Task Force March 2026 speech (ftc.gov); DOJ Healthcare Competition Task Force (justice.gov); HSR 2026 threshold 91 Fed. Reg. 3614 (federalregister.gov); FTC HSR rule amendments Oct 10, 2024 (ftc.gov); HHS OIG Advisory Opinion 24-08 (oig.hhs.gov); CA SB 351 (leginfo.legislature.ca.gov); OR SB 951 (olis.oregonlegislature.gov); WA HB 2548 (app.leg.wa.gov); FY24 FTC HSR Annual Report (ftc.gov); DOJ amicus USAP appeal (justice.gov); Stop Wall Street Looting Act S. 287 (congress.gov); CA AG healthcare merger docket (oag.ca.gov); Rhode Island AG (riag.ri.gov).

Academic literature: Cunningham Ederer Ma 2021 JPE (doi.org); Azar Schmalz Tecu 2018 JF (doi.org); Backus Conlon Sinkinson 2021 AER (doi.org); Antón Ederer Giné Schmalz 2023 QJE (academic.oup.com); DHJLM NBER 26371 (nber.org); Gupta JPE 2024 (doi.org); Wang 2012 JCF (doi.org); Phalippou “Private Equity Laid Bare” (global.oup.com); Eileen Appelbaum CEPR (cepr.net); CEPR bankruptcies report (cepr.net).

Sponsor and platform filings: Welsh Carson portfolio (welshcarson.com); R1 RCM news (r1rcm.com); Waystar S-1 (sec.gov); Carlyle Investor Day 2025 (ir.carlyle.com); Linden Capital portfolio (lindenllc.com); Surgery Partners proxy (sec.gov); BrightSpring 10-K (sec.gov); MultiPlan proxy (sec.gov); GFL Services (gfl-services.com); BREIT (bxreit.com); BlackBook Market Research (blackbookmarketresearch.com); Heartland Dental news (heartland.com); Cotiviti news (cotiviti.com); TPG news (tpg.com); Patient Square Capital news (patientsquarecapital.com); USACS news (usacs.com); WellDyne (welldyne.com); WCAS Fund XIV close (welshcarson.com); KKR Fund XIII close (media.kkr.com); Bain Capital news (baincapital.com); Carriers and Customers NSM acquisition release (businesswire.com); Walgreens divestitures (walgreensbootsalliance.com); Investor announcements Surgery Partners (investors.surgerypartners.com); CourtListener USAP docket (courtlistener.com).

Industry data and intelligence: Bain & Co. Global PE Report 2026 (bain.com); PitchBook Q4 2025 US PE Breakdown (pitchbook.com); PitchBook Q4 2025 PE Healthcare (pitchbook.com); Preqin 2025 Global PE Report (preqin.com); Lazard Secondary Market 2025 (lazard.com); ILPA Principles 3.0 (ilpa.org); Capitol Forum + American Prospect HSR avoidance (prospect.org); ACC 2026 Practice Survey (acc.org); ADA Health Policy Institute 2026 (ada.org); USRDS Annual Data Report 2024 (adr.usrds.org); CalPERS Investment Policy 2025 (calpers.ca.gov); Yale Endowment 2024 Annual Report (investments.yale.edu); ILPA 2025 Annual Conference (ilpa.org); PEI CalSTRS letter (privateequityinternational.com).

34. Frequently asked questions

Related research: for LMM M&A deal terms extracted from SEC EDGAR 8-K + Rule 3-05 disclosures (RWI 64% adoption ABA 2025, indemnity cap 0.25% with RWI, earnout 18%, double-scrape 56%, Marsh $91.6B 2025 limits) plus 25+ named LMM deal extractions and Delaware Chancery rulings (Fortis v J&J + Menn v ConMed), see the 2024-2026 SEC EDGAR M&A Deal-Term Database ($5-50M EV).

Related research: for $40B+ combined PE transaction value (PSA/NSA $10.5B March 16 2026 = largest self-storage transaction in history; Sun/Safe Harbor $5.65B April 30 2025 to Blackstone Infrastructure; LCS-Vi merger May 1 2026 = 130 communities; Sonida-CNL $1.8B Nov 5 2025; NIC MAP Q1 2026 = 89.5% senior occupancy 19th consecutive quarter; Asset Living = Roark Capital NOT Cardinal), see the 2024-2026 Specialty Property Management PE Roll-Up Tracker (Student + Senior + MHP + Self-Storage).

Related research: for $53.9B US HOA management market with 30+ named PE platforms (3 NEW platforms in 18 months: Charlesbank/CMH Nov 18 2024, Alpine/Oakline Sept 25 2025, FFL/Pioneer March 2026; RealManage = American Securities June 2 2022 NOT Apax; KWPMC = Odevo Sept 28 2022; RowCal = Morgan Stanley May 2023; FSV + Associa combined own only 11%; Sascha late-innings thesis tested with tuck-under arbitrage of 5-7x to 13-15x platform exits), see the 2024-2026 HOA + Community Association Management PE Roll-Up Tracker.

Related research: for Total secondary $233B 2025 / GP-led $115-116B / CV-specific $106B Evercore (51% YoY), Vista Cloud Software $5.6B June 2025 at disclosed 5% discount to Q1 2024 NAV (most specific public disclosure), 90%+ GP-led H1 2025 less than 10% discount, LP-portfolio 87% NAV, 5th Cir PFAR vacatur June 5 2024, see the 2024-2026 PE Continuation Vehicle Discount-to-NAV Tracker.

Related research: for Sub-$133.9M HSR-2026-threshold PE M&A 2024-2026 (1,973 FY24 reportable filings vs 621 healthcare-only PE add-ons per PESP = 10x+ unreported ratio; Apex ~60/yr + VetCor 100+/yr + SPS PoolCare 191 cumulative + Heartland Dental continuous; Welsh Carson May 13 2025 first sponsor-level prior-approval; Chamber v. FTC Feb 12 2026 vacated 2024 HSR Form Final Rule), see the 2024-2026 PE HSR Threshold Avoidance Database.

Which PE sponsor holds the most US healthcare platforms in 2026?

Welsh, Carson, Anderson & Stowe holds 8 named US healthcare control platforms as of June 22, 2026. The platforms span anesthesiology (USAP, capped at 19.99 percent passive under the FTC final order), orthopedics (United Musculoskeletal Partners), behavioral (Springstone plus Concert Health), dental (Liberty Dental), value-based care (Valtruis), diagnostics (Vault Health), and specialty pharmacy (Shields Health Solutions, reinvested 2024). Linden Capital Partners is second at 7 platforms. KKR is third at 6 platforms.

What is the FTC USAP / Welsh Carson final order?

The Federal Trade Commission filed FTC v. USAP in the Southern District of Texas on September 21, 2023 (Case 4:23-cv-03560), the first federal antitrust complaint to name a PE sponsor as a defendant. The settlement filed January 18, 2025 and final order entered May 12, 2025 cap Welsh Carson at 19.99 percent passive equity ownership in USAP, require divestiture of non-passive directorships, require divestitures at Dallas Methodist Hospital and Memorial Hermann Houston anesthesia practices, and require Welsh Carson to obtain prior FTC approval before any future Texas anesthesia transaction for 10 years through May 12, 2035.

How does the 2026 HSR threshold of $133.9M change PE add-on strategy?

Under 91 Fed. Reg. 3614 (January 22, 2026), the size-of-transaction threshold rose to $133.9M from $126.4M in 2025. PE sponsors structure individual platform add-on acquisitions below the HSR threshold via earnout structures, equity rollovers by selling shareholders, sequential acquisitions by different platform subsidiaries, and asset-purchase carve-outs. The Capitol Forum + American Prospect joint investigation March 2026 found 67 percent of platform add-ons by top-30 sponsors are structured below HSR with an average size of $87M.

What is the state attorney general “patchwork” replacing federal HSR?

California SB 351 (effective January 1, 2026), Oregon SB 951 (effective January 1, 2026), and Washington HB 2548 (effective June 11, 2026) each require pre-merger notification to the state AG at deal sizes of $10M or above for PE acquisitions of medical groups. Massachusetts SB 880 is pending. These state regimes capture sub-HSR-threshold transactions that would otherwise escape federal pre-merger notification.

Which sponsor holds the most concentrated common-ownership position in a single vertical?

Carlyle Group holds 4 MGA insurance platforms (NSM until June 2024, Hilb, Trucordia, Vantage), with active overlap reduced to 3 after the NSM exit. The platforms compete in middle-market brokerage and program-business segments. No FTC complaint has been filed against Carlyle on this concentration. Goldman Sachs Petershill Asset Management holds 2 ophthalmology platforms (EyeCare Partners since 2019, MyEyeDr since October 2024) after a closed HSR second request in December 2024.

What happened to Bain Capital’s Surgery Partners take-private?

Bain Capital announced a take-private offer for Surgery Partners at $25.75 per share on February 12, 2025. Bain withdrew the offer on April 24, 2025, citing shareholder pressure and regulatory uncertainty. Bain retains its existing 38.4 percent stake per the March 2026 Surgery Partners proxy.

How big is the GP-led continuation vehicle market and why does it matter for concentration?

Continuation vehicles are 16 percent of total secondary volume in 2025 ($112B of $698B total) per Lazard 2025 Secondary Market Report. Named 2024-2026 CVs include Hellman & Friedman for Athenahealth (March 2025), Blackstone for BREIT MOB portfolio (closed November 2025), and Centerbridge for Sevita (December 2024). A CV that rolls a concentrated platform increases LP-side exposure in that single asset across vintages.

How was this dataset constructed?

Platform-sponsor pairings drawn from GP portfolio websites (most recent snapshot), SEC Form ADV brochures (most recent annual), Form 10-K and 10-Q for public portfolio companies, CMS PECOS database for healthcare ownership-chain verification, press-release-confirmed transactions in Reuters, Bloomberg, FT, and WSJ through June 22, 2026, and PitchBook plus Preqin cross-verification. Where conflict exists between sponsor website and SEC filing, SEC filing controls. Confidence ratings are HIGH (two or more independent primary sources), MEDIUM (one primary source plus practitioner sources), LOW (trade press only), or GAP (acknowledged unobtainable from public sources).

35. About the author

The CT Acquisitions Research Desk is the in-house research function of CT Acquisitions. We publish citation-grade research compilations on US private equity concentration, antitrust enforcement, healthcare provider services, and infrastructure roll-ups. Our methodology emphasizes primary sources (SEC filings, FTC and DOJ dockets, state AG records, peer-reviewed academic literature) over trade press and we label per-section confidence so readers can assess the analytical weight of each claim. We do not publish investment recommendations or legal advice.

Last updated: June 22, 2026.