By Jeff Axelrod ·

Medical Office Building: The Investor Guide to MOB Underwriting

Medical office buildings are the most defensible niche in CRE. After $2B in CRE acquisitions, here is what makes MOB underwriting different.

What I learned about MOB from $2B in CRE acquisitions

In ten years on the buy side, including five as a Director of Research, my team underwrote and closed more than $2B in CRE acquisitions across asset classes. I was not a dedicated medical office investor — my work focused on the larger conventional CRE categories — but MOB came up enough on the underwriting bench that I built a strong working view of what makes the asset class different, and where institutional buyers were paying for things they didn’t fully understand.

This piece is the version of medical office building diligence I would give an acquisitions analyst rotating onto a healthcare real estate desk for the first time. What MOB actually is, how it behaves differently from conventional office, what an institutional underwrite has to cover, and where the 2026 market is pricing.

If you’re searching this term as a patient or a clinician looking for a location, this is not that piece. This is the investor view.

What an MOB actually is

A medical office building is a commercial property purpose-built or substantially adapted for outpatient healthcare delivery. The label is widely used and only loosely defined. In practice the institutional MOB universe breaks into four sub-categories, and the distinctions matter for underwriting.

On-campus, hospital-anchored

Located on or directly adjacent to an acute-care hospital campus, often connected by skywalk or tunnel. Tenants are predominantly affiliated with the host hospital system through employment, joint venture, or referral relationship. These are the highest-quality MOB assets — long WALT, investment-grade or near-investment-grade tenancy through the hospital system credit, very low turnover. They trade at the tightest cap rates in the asset class.

Off-campus, single-system affiliated

Hospital systems increasingly run outpatient operations from off-campus locations to capture patients closer to home and reduce inpatient cost basis. These buildings retain strong tenant credit through the system relationship but trade at modestly wider cap rates than on-campus, reflecting the absence of physical hospital adjacency.

Off-campus, multi-tenant non-affiliated

The largest segment by building count. Multiple physician group tenants, often a mix of primary care, specialty, imaging, and dental, with no single hospital affiliation. Tenant credit is much more variable here — some practices are part of large physician groups with meaningful balance sheets, many are small partnerships with the principals personally guaranteeing the lease. Cap rates are 100–200 basis points wider than on-campus equivalent.

Ambulatory surgery centers and specialty facilities

Single-tenant or anchor-tenant buildings configured around an ambulatory surgery center (ASC), dialysis center, oncology infusion suite, or imaging center. These are operating-business-adjacent properties — the tenant’s regulatory licensure, CMS certification, and Certificate of Need status are integral to the real estate value.

If a broker hands you an offering memorandum that says “medical office,” the first question is which of these four sub-categories the asset belongs to. The pricing, the diligence list, and the risk profile diverge meaningfully.

Why MOB behaves differently from conventional office

This is the part of the asset class that has been re-priced over the last five years and is now well understood by allocators, but is worth restating because the structural drivers are durable, not cyclical.

Tenants are physically anchored

A typical clinical tenant has invested $150 to $300 per square foot in build-out — exam rooms, plumbing, casework, specialized HVAC, sometimes radiation shielding or medical gas. A law firm can move offices over a long weekend. A surgical practice with three procedure rooms cannot.

Patient bases are location-loyal

Primary care, specialty, and especially imaging and dialysis carry a geographic patient base built over years. Relocating to a different sub-market often means losing a meaningful share of the patient panel. Patient-base stickiness is real even when reimbursement is portable.

Licensure attaches to specific addresses

State health department licenses, CMS certifications, ASC accreditations, and many specialty licenses are tied to the physical site. Moving requires re-credentialing — months of administrative cost and revenue interruption.

Demand is decoupled from the office cycle

Office demand correlates with corporate earnings, hiring, and remote-work policy. MOB demand correlates with population aging, procedure migration to outpatient, and reimbursement policy. These cycles do not move in step. Through 2022–2025 the divergence has been stark: conventional office vacancy rose materially while MOB occupancy industry-wide held above 90%.

Lease structures favor the landlord

MOB leases are typically triple-net, with longer initial terms than conventional office (7–10 years not uncommon on new build-out), embedded rent escalators, and limited tenant-favorable termination rights. The reason is leverage: tenants in clinical space have very limited substitute locations.

The composite effect is an asset class with structurally lower tenant turnover, more predictable cash flow, and lower sensitivity to the conventional office cycle. That is the institutional thesis, and it has held up.

The tenant credit framework

Underwriting MOB tenant credit is the part most analysts get wrong on their first deal. The right framework is to stratify the rent roll by tenant type, then size each stratum’s credit individually.

Hospital systems and large physician group tenancy. Investment-grade or near-investment-grade where the parent is a large not-for-profit system or publicly traded operator (HCA, Tenet, Universal Health Services). Pull the system’s bond rating, recent financial statements, and any operational concerns at the local facility level. A nationally strong system with a struggling local hospital is a different underwrite than a nationally strong system with a strong local facility.

Individual physician practices and small partnerships. Credit is the practice’s revenue, payor mix, and the principals’ personal balance sheets. Standard diligence: trailing three years of P&L, current accounts receivable aging, CMS exposure as a percentage of revenue, and the personal financial statements of any guarantors. A profitable physician practice is a strong tenant. A practice running tight on cash with concentrated Medicare exposure is a different proposition.

Ambulatory surgery centers and dialysis. Often part of larger operating platforms — DaVita and Fresenius dominate dialysis, USPI (Tenet) and SCA Health (Optum) dominate ASCs. Parent credit is the primary lens, but the specific facility’s CMS certification, CON status if applicable, and case volume matter operationally.

Dental, vision, and ancillary tenants. Typically lower-credit tenancy with shorter leases and personal guarantees. Underwrite as small business credit, not healthcare credit.

The rent roll question I always asked first: what percentage of base rent comes from investment-grade-or-better credit? On Class A on-campus MOB that number is often 80%+. On multi-tenant off-campus that number is often under 30%. The cap rate spread between those two profiles exists for a reason.

Healthcare-specific lease provisions that don’t show up in standard CRE

Standard CRE due diligence covers rent, term, options, exclusives, OPEX, CAM, and common operational provisions. MOB leases layer on healthcare-specific provisions that an analyst trained on conventional office will not always recognize.

Stark Law and Anti-Kickback compliance. Federal law restricts financial relationships between physicians and entities to which they make Medicare referrals. If a hospital-affiliated landlord rents space to a physician who refers Medicare patients to the affiliated hospital, the lease has to meet specific safe-harbor requirements: rent set in advance, fair market value, commercially reasonable, written, and at least a year long. Acquisition diligence requires verifying compliance and reviewing the fair-market-rent appraisals supporting current rents.

Fair market value rent appraisals. Where Stark applies, every physician lease typically has an underlying FMV appraisal on file. These appraisals are the legal defense if the rent is ever challenged. Confirm they exist, are current (typically refreshed every 3 years), and reflect the actual lease terms.

Exclusive use by specialty. Many MOB leases grant exclusive rights for specific clinical specialties — only one orthopedic group, only one cardiology group, only one imaging center. These provisions constrain leasing flexibility on rollover and need to be inventoried, not just acknowledged.

Hospital affiliation provisions. On-campus and system-affiliated MOBs often include provisions tied to the tenant’s continued affiliation with the host system, credentials at the affiliated hospital, or membership in a specified physician group. Loss of affiliation can trigger termination rights or rent changes.

Tenant improvement and reuse provisions. Because clinical build-outs are expensive and specialty-specific, leases often allocate TI obligations differently than conventional office, and include provisions about what happens to clinical infrastructure at lease end.

Operational provisions. Hazardous and biomedical waste handling, after-hours access for emergency procedures, generator backup obligations, parking ratios calibrated to clinical use (typically 5–7 per 1,000 sf versus 3–4 for conventional office).

None of this is exotic. It is just specific to the asset class and has to be read carefully by someone who has seen the patterns before, or with the help of healthcare real estate counsel.

The 2026 MOB market

Where we are entering 2026:

Cap rates. Class A on-campus hospital-anchored has been trading roughly 6.50% to 7.00% in primary markets through early 2026. Class B off-campus multi-tenant sits in the 7.50% to 8.50% range. Single-tenant net-lease MOB with strong credit trades tighter than equivalent multi-tenant. The spread to conventional office cap rates has compressed materially since 2022, reflecting the re-pricing of MOB defensiveness — but the spread to industrial and multifamily has not compressed nearly as much, so the asset class still prices wider than the most institutional categories.

Capital flow. Healthcare Realty Trust (HR) is the largest pure-play public MOB REIT. Healthpeak (DOC) and Welltower (WELL) carry significant MOB allocations. On the private institutional side, Anchor Health, Caddis, Montecito Medical, IRA Capital, and Remedy Medical Properties are the names you see most often on closings. Hospital systems themselves are increasingly direct owners, often via joint venture structures with REIT partners.

Operations. Industry-wide MOB occupancy has held above 90% through the cycle, with the best on-campus assets running 95%+. Same-store NOI growth for the dedicated MOB REITs has been in the 2–4% range, slower than industrial or multifamily but positive when most office REITs were posting declines.

The honest read. MOB is no longer the contrarian thesis it was a decade ago. The cap rate compression has happened, the institutional capital is committed, and the demographic story is well understood. Alpha now comes from sub-market selection, tenant credit work, and operational expertise — not from buying the asset class label.

A workable MOB acquisition workflow

For an acquisitions team with general CRE muscle but not deep healthcare specialization, here is the workflow I’ve used when underwriting MOB opportunities.

  1. Sub-categorize the asset. On-campus hospital-anchored, off-campus system-affiliated, off-campus multi-tenant, or specialty (ASC, dialysis, imaging). Each gets a different diligence playbook.
  2. Stratify the rent roll by tenant credit type. Hospital systems and large groups, individual practices, ASC operators, ancillary. Calculate weighted average credit-weighted WALT, not just headline WALT.
  3. Pull payor mix for each clinical tenant. What percentage of practice revenue comes from Medicare, Medicaid, commercial, and self-pay. Concentration above 60% in any single payor — especially government — is a flag.
  4. Verify Stark and Anti-Kickback compliance for every applicable lease. Where there is a hospital affiliation, every physician lease needs the fair-market-rent documentation. Catalog any gaps.
  5. Physical inspection by healthcare-specialized engineer. HVAC capacity for clinical loads, medical gas systems, generator backup, radiation shielding, biomedical waste, ADA to clinical standards. A conventional commercial PCA will miss things.
  6. Confirm regulatory status for each clinical tenant. State licensure current, CMS certification current, Certificate of Need status where applicable, any open compliance items.
  7. Run a downside case on tenant retention. If your two largest tenants vacate, what is the time and capital required to re-tenant a clinical suite? This is materially different from conventional office re-tenanting because of build-out cost and licensure transfer.

When this workflow runs cleanly, what you find is whether the offering pricing reflects the actual risk-adjusted cash flow profile. When it doesn’t, you find the things that move pricing in negotiation.

Where DDee fits

DDee.ai is a CRE due diligence platform — AI-powered document analysis built for institutional acquisitions teams. We are asset-class agnostic. The same workflow that surfaces estoppel inconsistencies on a retail deal, or non-conforming use risk on industrial, runs against an MOB rent roll, lease set, and operating documents. For MOB specifically, the lease abstraction layer pulls out healthcare-specific provisions — Stark compliance language, exclusive use clauses by specialty, hospital affiliation provisions, FMV appraisal references — alongside the standard CRE fields. The diligence checklist generation includes the MOB-specific buckets above.

We don’t claim MOB specialization the way Caddis or Anchor Health do. We claim general CRE diligence speed and a lease abstraction product that pulls out clinical-lease-specific fields cleanly. For an acquisitions team that does MOB occasionally as part of a broader strategy, that’s typically what’s needed.

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Frequently Asked Questions

What is a medical office building?
A medical office building, or MOB, is a commercial property purpose-built or adapted for outpatient healthcare delivery. Tenants are physician groups, hospital systems, ambulatory surgery centers, imaging and diagnostics, dialysis, dental and specialty practices, and increasingly tele-health backed providers. The defining feature is not the floorplate — it is the clinical infrastructure: enhanced HVAC for procedure rooms, medical gas piping in some suites, dedicated waste handling, plumbing density well above conventional office, and code-compliant exam rooms. MOB is a healthcare real estate asset class, not an office sub-type.
How is a medical office building different from a regular office building?
Three structural differences. Tenant stickiness is materially higher — clinical build-outs run $150–$300 per square foot, patient bases are location-loyal, and licensure ties tenants to specific physical sites. Revenue source is healthcare reimbursement, not corporate earnings, so the demand driver is decoupled from the broader office cycle. Lease structures are heavier on landlord-favorable provisions, including healthcare-specific compliance language for Stark Law and Anti-Kickback, fair market value rent requirements when there is a referral relationship, and longer initial terms. Net effect: MOB tenant retention industry-wide runs north of 80% on rollover, versus a conventional office market that is structurally challenged.
What are typical cap rates for medical office buildings in 2026?
Class A on-campus hospital-anchored MOB has been trading roughly 6.50% to 7.00% in primary markets through early 2026, with the best assets — investment-grade hospital system credit, long WALT, sub-market locations — clearing inside that range. Class B off-campus multi-tenant MOB sits roughly 7.50% to 8.50% depending on tenant credit and lease structure. Single-tenant net-lease MOB with strong credit can trade tighter than multi-tenant equivalents. Cap rate spreads to conventional office have compressed since 2022 as MOB's relative defensiveness has been re-priced into the asset class.
Who are the major institutional owners of medical office buildings?
Healthcare Realty Trust (HR) is the largest dedicated MOB REIT following its merger with Healthcare Trust of America. Healthpeak Properties (DOC, post-merger ticker) owns one of the largest medical outpatient portfolios. Welltower (WELL) has meaningful MOB exposure alongside senior housing. On the private side, Anchor Health Properties, Caddis Healthcare Real Estate, Montecito Medical Real Estate, IRA Capital, and Remedy Medical Properties are active institutional buyers. Hospital systems themselves are increasingly significant — many own their on-campus MOBs outright or via joint venture with a healthcare REIT.
What is Stark Law and why does it matter for MOB acquisitions?
The Stark Law and the federal Anti-Kickback Statute restrict financial relationships between physicians and entities to which they make referrals for Medicare-reimbursed services. In an MOB context, this means rents charged to physician tenants who refer to a co-located hospital must be at fair market value, set in advance, and commercially reasonable. Acquisition diligence requires verifying that existing leases meet the fair-market-rent test, that any concessions are documented and defensible, and that valuation appraisals supporting current rents are on file. A Stark or Anti-Kickback violation can trigger meaningful civil penalties and disgorgement — material to underwriting.
What due diligence is specific to medical office building acquisitions?
Beyond standard CRE diligence, four MOB-specific buckets. Regulatory: state Certificate of Need (CON) status for any ambulatory surgery center tenants, occupational licensure on file for each clinical tenant, biomedical waste compliance. Physical: HVAC capacity and zoning for clinical use, medical gas certification, radiation shielding for imaging suites, generator backup adequacy, ADA compliance to clinical standard. Lease: Stark and Anti-Kickback compliance language, fair market rent appraisals on file, exclusive use clauses by specialty, hospital affiliation provisions if on-campus. Tenant: CMS reimbursement exposure of each practice, payor mix, parent guarantor if part of a larger group, hospital health system credit if hospital-anchored.
Is medical office building a good investment in 2026?
On a risk-adjusted basis, MOB has outperformed conventional office through 2022–2025 by a wide margin and that gap has not closed. Demographics — the over-65 cohort growing roughly 3% annually — support sustained outpatient demand. Reimbursement headwinds exist, but the structural shift of procedures from hospital inpatient to outpatient settings continues. The honest investor answer: yes, but the cap rate compression already reflects much of the consensus view. Alpha now comes from disciplined sub-market selection, tenant credit work, and operational expertise — not from buying the asset class label.