Medical Office Buildings: Single-Tenant Credit vs Multi-Tenant, WALT, On-Campus Premium, and the 2026 MOB Market

Key Takeaways

The 2026 MOB Market

The medical outpatient building (MOB) sector entered 2026 with strong institutional fundamentals.RevistaMed's 3Q2026 top-100-metro datashows 92.2% trailing-twelve-month occupancy across 1.11B SF of inventory, with completions down 27.3% year over year and 25.2M SF (about 2.3% of inventory) under construction. Record asking rent at $25.46/SF perCBRE's Q2 2026 US Medical Outpatient Buildings Figures. Cap rates at 7.1% sector-average on the same CBRE print, roughly stable year-over-year; Cushman & Wakefield's H1 2026 capital-markets read has the sector at 6.8%, down 35 basis points year-over-year. Investment volume $2.7B in Q2 2026, up 24% year-over-year. In the Apers view, the MOB sector spent 2023–2024 in the same rate-driven pricing freeze as the rest of CRE and has since recovered into a backdrop of modest supply growth with structural demand tailwinds.

The institutional reader is back, the brokerage research is publishing, the capital is moving.Healthpeak Properties(NYSE: DOC), which owns outpatient medical and lab properties, closed its merger with Physicians Realty Trust on March 1, 2024.Healthcare Realty Trustreports $10.7B of total investments, 32.8M SF and 563 properties at year-end 2025. Welltower entered a definitive agreement to sell a portfolio of 319 outpatient medical properties for approximately $7.2B, about $6.0B of net proceeds after a reinvestment into a preferred interest, in tranches. The sale is now substantially closed:Welltower's Q2 2026 10-Qreports 311 properties disposed under the agreement through June 30, 2026, with the remaining tranches expected to close by the end of 2026.

What follows is the institutional underwriting discipline at the bifurcation that defines the sector: single-tenant credit MOB versus multi-tenant MOB. Different lease structures, different return drivers, different risk concentrations, different cap-rate ranges, different institutional buyers. Inside that framework we walk the weighted average lease term (the metric most often invoked in MOB diligence and least often calculated correctly), both rent-weighted and space-weighted on the same rent roll. We walk the on-campus vs off-campus differential, which is the most important MOB submarket distinction. We walk the credit-tenant lease underwriting framework specialized for medical tenants. We build an eight- bucket 2026 cap-rate range table, an Apers synthesis anchored on CBRE, RevistaMed, and Cushman & Wakefield sector data. And we work two illustrative deals end to end: Deal A, a single-tenant credit MOB on a hospital campus; Deal B, an 11-tenant off-campus MOB in a top-100 Sun Belt metro.

Single-Tenant Credit vs Multi-Tenant - the Central Decision

Every institutional MOB conversation starts with one question: is it single-tenant credit or multi-tenant? The bifurcation is not a categorization - it is the underwriting decision that determines which framework you apply, which cap-rate range you anchor on, which risk concentrations you stress, and which institutional buyer pool the asset trades into.

Single-tenant credit MOB. One tenant under one lease. The tenant is typically a hospital system (often investment-grade rated), a large physician group, or a PE-backed ambulatory surgery center. Lease structure is NNN or absolute net - tenant covers taxes, insurance, CAM, and frequently roof and structure. Initial term 10–15 years, with two or three 5-year options at FMV or fixed strike. Escalations fixed (2–3% annual) or CPI with floor and cap. The lease document IS the asset; WALT collapses to the remaining lease term plus option-period and guarantee adjustments. Cap-rate determinants: guarantor credit rating, remaining term, escalation structure, on/off-campus position. Underwriting is the credit-tenant lease (CTL) framework - closer to single-tenant net lease investing than to traditional office. Buyer pool: core MOB-dedicated platforms (Anchor Health, Davis, Catalyst, Montecito), 1031/DST capital, life-company-financed family-office aggregators.

Multi-tenant MOB. Ten to thirty physician group practices, often anchored by one or two larger tenants (multi-specialty group, imaging center, ASC) with smaller practices behind (primary care, single-specialty, lab, diagnostic). Lease structure modified gross or NNN-with-base-stop - landlord retains some pass-throughs. Initial terms 5–10 years; similar escalation structures. WALT is distributed across the rent roll and must be computed both rent-weighted and space-weighted (cash-flow vs rollover concentration). Cap-rate determinants: tenant mix, occupancy trajectory, submarket healthcare demand, on/off-campus position, operational asset-management quality. The underwriting framework is closer to traditional office economics, adjusted for the healthcare stickiness that makes medical tenants materially more durable than general office tenants. Buyer pool: healthcare REITs (Healthpeak/DOC, Healthcare Realty Trust), MOB funds (Catalyst, Hammes, Pacific Medical Buildings), operationally capable family offices.

The side-by-side framework table below is the article's spine. Every subsequent section returns to it.

Table 1. The single-tenant credit MOB vs multi-tenant MOB framework (occupancy, retention, cap-rate and WALT bands are Apers illustrative ranges, not published statistics). The bifurcation determines underwriting framework, risk concentrations, return drivers, and the institutional buyer pool the asset trades into.

A useful test for which side of the bifurcation a deal falls on: if the lease document is more important than the rent roll, it is single-tenant credit MOB. If the rent roll is the artifact you spend two hours reading column by column, it is multi-tenant MOB. The article that parallels this discipline on the multifamily side is themultifamily rent roll reading exercise - multi-tenant MOB shares the rent-roll discipline; single-tenant MOB shares the document-discipline ofNNN office lease analysis.

Single-Tenant Credit MOB - the Lease Is the Asset

When the building has one tenant on a 10–15 year NNN lease, the underwriting framework is the credit-tenant lease framework. The lease document is what you are buying. Read it the way a bond analyst reads an indenture: covenant by covenant, credit support by credit support, with the cap rate falling out of the cumulative risk profile. Six components drive the cap-rate calibration. The basis-point sensitivities below are Apers practitioner rules of thumb, not published statistics.

1. Guarantor credit rating tier. Three tiers dominate. Investment-grade health systems (S&P BBB- / Moody's Baa3 or higher) are the credit tenants the institutional market underwrites at 5.5–6.5% cap on long-WALT NNN MOB (Table 5, buckets 1 and 2). Large physician groups ($50M+ revenue, 20–200 physicians, often private-equity-backed multi-specialty platforms) are usually unrated and trade wider, at roughly 6.3–7.5% (buckets 3 and 4). Small practices with personal guarantees and a tangible-book practice balance sheet trade 7.0–7.8% (bucket 5). These ranges are Apers estimates.

2. Parent-co guarantee structure. Where the operating tenant is a local affiliate, the parent-co guarantee structure is decisive. System-level guarantee from the rated parent corporation, with cross-default to other system obligations, is the institutional gold standard. A local-affiliate-only guarantee - where the parent has no obligation if the affiliate fails - is worth 50–150 basis points in cap rate spread. Corporate-shell guarantees from entities with no operating-asset backing should be priced as if the underlying is unguaranteed.

3. Lease term and remaining term. Initial term 10–15 years is institutional standard. Remaining term - the WALT - is the institutional driver of cap rate on a stabilized credit MOB. As an Apers rule of thumb, sub-3-year remaining term trades 100–150 bps wider than 10+ year remaining term on the same credit. Institutional core MOB cap-rate quotes assume 10+ year remaining term; anything shorter requires a re-tenanting or extension thesis baked into the underwriting.

4. Escalation structure. Fixed annual escalation (2–3%/yr) is institutional baseline - the escalator compounds reliably, debt sizes against it. CPI-linked with floor (1–3%) and cap (4–5%) is acceptable to most institutional buyers, particularly insurance-company debt that prices off a real-rate framework. Fixed-step (e.g., 10% every five years) is worst for inflation hedging and for debt sizing because the lender models the escalation at the lower bound between steps; institutional buyers price fixed-step paper 25–50 bps wider than equivalent fixed-annual.

5. Options to extend and rights to terminate. Five-year extension options at fair market value are neutral. Fixed-strike extensions below market are a discount to the landlord (tenant captures the spread). Early-termination rights for change-of-control or "for convenience" with notice are red-flag without a compensating premium; the most common institutional structure is a tenant termination right at year 7 or year 10 with 12 months notice and a termination fee equal to 6–12 months base rent. The spread between FMV and fixed-strike at the option date is often 15–25% of the asset's exit value.

6. Exclusive-use, ROFR, and hospital subordination. Exclusive-use clauses restrict the landlord's ability to release space to competing practices and sometimes extend a radius beyond the building - critical in multi-tenant operations, less material in single-tenant credit. Right-of- first-refusal (ROFR) clauses give the tenant first right to purchase if the landlord receives a third- party offer; common on hospital-anchored on-campus MOB and price 25–50 bps wider for the constrained exit pool. Hospital subordination provisions are the most important institutional risk concentration: where the MOB sits on a hospital ground-leased site, the hospital's closure or bankruptcy can collapse the MOB lease economics because the credit support behind the practice tenants evaporates if the hospital they refer from closes. TheMedical Properties Trustfactual reference (covered in the consolidation section below) is the cautionary case for what happens when CTL underwriting fails on the underlying tenant credit.

Table 2. The credit-tenant lease underwriting framework for medical tenants: nine components, each with an Apers rule-of-thumb cap-rate sensitivity (not a published statistic). Read the lease document with this table open; price the deviations.

The institutional discipline on single-tenant credit MOB is to price each deviation from institutional standard against the comp-set CTL cap-rate range, then layer the incremental basis-point adjustments to arrive at the underwriting cap. The Table 2 sensitivities overlap (credit tier and guarantee structure, for example), so they are not simply additive: start from the Table 5 bucket that matches the credit tier and add only what that bucket does not already capture. A clean IG hospital-system NNN with 12 years remaining, 2.5% fixed annual escalators, three 5-year FMV options, no early termination, and a system-level guarantee on a building that is not hospital-ground-leased prices into the tightest tier of the range (5.5–6.0% in 2026). A large physician-group, sub-IG, with 8 years remaining, local-affiliate-only guarantee, one option at fixed strike, and a 7-year termination right prices wider, in the 6.8–7.5% range (bucket 4 if off-campus). Thecap rate calculator and formula articlewalks the basic mechanics; the medical-CTL specialization layers the credit-tenancy adjustments on top.

WALT: Rent-Weighted and Space-Weighted, Walked

Weighted Average Lease Term (WALT) is the institutional MOB metric most often invoked and least often calculated correctly. Many published walkthroughs, including thePropertyMetrics WALT explainer(which defines WALT as weighted by either rental revenue or square footage, then walks only the rent-weighted example), show a single weighting method. The institutional discipline is to compute and report both weightings on every multi-tenant rent roll.

Rent-weighted WALT. The income-weighted average. Each tenant's remaining lease term is weighted by that tenant's share of total annual rent. Formula:

WALT_rent = Σ (annual_rent_i × remaining_term_months_i) / Σ annual_rent_i

What it captures: cash-flow concentration risk. A building where the anchor tenant pays 50% of the rent and has 15 years remaining shows a long rent-weighted WALT even if half the small tenants are rolling in 24 months. The lender, the equity underwriter, and the rating agency all look at rent-weighted WALT first because cash flow is what services debt and pays distributions.

Space-weighted WALT. The square-footage-weighted average. Each tenant's remaining lease term is weighted by that tenant's share of total occupied square footage. Formula:

WALT_sf = Σ (sf_i × remaining_term_months_i) / Σ sf_i

What it captures: rollover concentration risk. The same building above might have a much shorter space-weighted WALT if the small tenants collectively occupy 65% of the leasable square footage. Space-weighted WALT tells the leasing team how much physical space they must release over the holding period and tells the asset manager how much rollover risk sits in the portfolio independent of the anchor's cash-flow contribution.

The institutional read: report both. Rent-weighted is the headline number quoted in offering memoranda; space-weighted is the cross-check that surfaces rollover risk hidden by anchor concentration. A material spread between the two - for instance, rent-weighted at 10.5 years and space-weighted at 6.2 years - tells you the rent roll is anchor-dependent and the small-tenant rollover is the operational workload.

Walk the math on a worked 12-tenant multi-tenant on-campus MOB. The rent roll:

Table 3. Worked 12-tenant on-campus multi-tenant MOB rent roll, the input to both WALT computations. The roll is illustrative; its in-place rents sit below the Table 4 on-campus asking range.

The hospital-system anchor occupies 35.8% of the square footage and contributes 36.7% of the annual rent, so the roll is balanced. Remaining terms range from 24 months (urology) to 156 months (hospital-system anchor); the imaging center is next at 96 months.

Compute both. Sum (annual_rent × remaining_term) across all 12 tenants: $198,944,850. Sum of annual rent: $2,002,950. Rent-weighted WALT = $198,944,850 / $2,002,950 = 99.3 months ≈ 8.3 years. Sum (sf × remaining_term) across all tenants: 7,158,900. Sum of SF: 73,300. Space-weighted WALT = 7,158,900 / 73,300 = 97.7 months ≈ 8.1 years.

The institutional read: rent-weighted WALT at 8.3 years and space-weighted WALT at 8.1 years. The spread of 1.7 months (about 0.14 year) is narrow because the hospital-system anchor occupies a roughly proportional share of both rent and space - a well-mixed rent roll without acute anchor concentration. A different rent roll - one where the anchor pays 60% of the rent on 30% of the space - would show a much wider spread (rent-weighted WALT pulled up by the anchor, space-weighted pulled down by the tail). Always compute both; the spread itself is the diagnostic.

Single-tenant collapse. For a single-tenant credit MOB, both WALT calculations collapse to the remaining lease term - the building has one tenant occupying 100% of the space and contributing 100% of the rent. The institutional adjustment that matters is the effective WALT: remaining contractual term plus the credit-weighted value of option periods plus the credit-weighted value of the parent-co guarantee. For an IG hospital-system credit with 12 years remaining, three 5-year FMV options, and a system-level guarantee, effective WALT extends meaningfully beyond 12 years - an illustrative Apers treatment is something closer to 18–22 years for sizing purposes, with appropriate discounting for option exercise probability.

On-Campus vs Off-Campus - the Submarket Distinction

Once you have the single-vs-multi bifurcation and the WALT discipline, the next institutional question is the submarket distinction that drives everything from rent to retention to cap rate: on-campus or off-campus.

On-campus definition. The MOB sits within roughly 1/4 mile of an acute-care hospital, typically on a campus owned or controlled by the hospital system. The land beneath the building is frequently a ground lease from the hospital (50–99 year terms) with hospital ROFR and subordination provisions. The tenants are integrated into the hospital's referral network - physicians on staff at the hospital, specialty groups receiving referrals from the hospital's primary care network, imaging and lab tenants serving both inpatient and outpatient orders from the hospital's EHR.

Off-campus definition. The MOB is not on a hospital campus. It may be near complementary healthcare infrastructure (urgent care, freestanding ASC, diagnostic imaging center, freestanding ED) but operates without direct hospital integration. Off-campus product is typically owned in fee, not on a ground lease, and the tenant base is a mix of independent practices, hospital-system satellite locations, and physician groups serving an outpatient demand area.

The on-campus premium is a structural rent and cap-rate spread reflecting hospital integration and the limited supply of on-campus product (you can't build on-campus MOB without a hospital partner; the hospital controls the supply). The premium plays through in several channels. The ranges in Table 4 are an Apers synthesis, not published statistics.

Table 4. On-campus vs off-campus MOB differential (Apers synthesis; illustrative ranges, not published statistics). Versus off-campus Class A, the on-campus premium plays through in rent (about $8/SF at the range midpoints), occupancy (about 5 points), retention (about 6 points), and cap rate (50–100 bps tighter, about 75 bps at the range midpoints). Versus off-campus Class B/C, the cap-rate gap is 100–250 bps.

The Table 4 rent bands sit around two market-wide benchmarks. InRevistaMed's3Q2026 data, average NNN rent across the top 100 metros ran $26.59/SF, up 3.1% year over year. CBRE's Q2 2026 record asking rent was $25.46/SF. Both are mixed-sample averages; Table 4 places on-campus Class A above them and off-campus Class B/C below them.

Why the premium exists. Three structural drivers: (1) referral integration - tenants on-campus capture referrals from hospital-based physicians and from primary care practices in the hospital's network, supporting higher willingness-to-pay on rent; (2) proximity to acute care, which lets surgical and procedural specialties admit patients quickly to the hospital and coordinate complex care across the inpatient/outpatient boundary; (3) supply constraint - on-campus product cannot be built without a hospital ground-lease partner, and most hospitals develop their own MOB pipeline with developer partners (Hammes, Caddis, Rendina, MedCraft, Pacific Medical Buildings, Anchor Health) on extended lead times, deliberately constrained.

Why the premium narrows. Two countervailing factors. Hospital subordination tail risk - if the hospital closes or files Chapter 11 (Steward Health Care, Prospect Medical, Hahnemann are the institutional reference cases), the on-campus MOB loses its referral network and the tenant base unwinds. Exit liquidity constraint - ground-leased on-campus MOB has a thinner institutional exit pool because the ground lease and hospital ROFR limit the buyer set; the cap-rate premium is partially compensation for the exit constraint, not just for the hospital tail risk. The institutional read: on-campus is core MOB; off-campus is the wider opportunity set with broader buyer pool and more operational beta. Most institutional MOB platforms run a barbell of on-campus core and off-campus core-plus to balance the portfolio risk profile.

The 2026 Cap Rate Range - Eight Buckets

The 2026 MOB cap rate is published as sector averages by CBRE, Cushman & Wakefield, and RevistaMed, but not as a table split by credit tenancy and on-campus/off-campus position. Below is the Apers synthesis: eight illustrative buckets anchored on those sector averages. The bucket ranges are Apers estimates, not published statistics.

Sector anchor data points: CBRE Q2 2026 sector cap at 7.1% (roughly stable, up 4 bps YoY) with transaction volume $2.7B (+24% YoY) and record asking rent $25.46/SF per theCBRE Q2 2026 figures release. Cushman & Wakefield's H1 2026 capital-markets read: sector cap 6.8% (down 35 bps YoY) on $6.7B of first-half volume (+21% YoY), with portfolio sales that more than doubled from a year earlier and single-asset sales up 42% to $3.4B.RevistaMedputs the average MOB cap rate flat at 6.7% from the end of 2025 through the first half of 2026, with an average value of $387/SF in 2Q26 versus $370/SF at the end of 2025. Healthcare Realty's FY2025 10-K reports 70 properties sold in 2025 for approximately $1.1B at a 6.7% weighted-average cap rate. The integrated eight-bucket table:

Table 5. The 2026 MOB cap-rate range, an Apers synthesis (illustrative ranges, not published statistics): eight buckets integrating credit tenancy, WALT, and on-campus/off-campus position. The roughly 50 bps on-campus adjustment is an Apers judgment. Sector anchor data: CBRE 7.1% Q2 2026; Cushman & Wakefield 6.8% H1 2026; RevistaMed 6.7% average through H1 2026.

The 300-bps spread from tightest (5.50%, profile #1 - investment-grade hospital system, 10+ year WALT, on-campus) to widest (8.50%, profile #8 - multi-tenant, off-campus, Class B/C, secondary metro) is the institutional underwriting range. The CBRE Q2 2026 sector average of 7.1% sits roughly at the middle of the range. Cushman & Wakefield reports that portfolio sales more than doubled in H1 2026 while single-asset sales rose 42%; any portfolio-versus-single-asset adjustment applies on top of the bucket, not inside it. Thecap rate calculator articlewalks the basic NOI / value mechanics; the eight-bucket framework above is the medical-CTL-overlay calibration.

The 2026 Healthcare REIT Consolidation

The capital-markets backdrop matters most. Healthcare REIT portfolio activity has reshaped institutional MOB ownership in 2024–2026.

Healthpeak Properties + Physicians Realty Trust (NYSE: DOC). Healthpeak closed its merger with Physicians Realty Trust on March 1, 2024 and trades under the DOC ticker. PerHealthpeak, its portfolio spans Outpatient Medical and Lab properties, so it is a diversified healthcare REIT with a large outpatient medical platform rather than a pure-play outpatient owner.

Healthcare Realty Trust (NYSE: HR). Per itsFY2025 10-K, HR reports total investments of approximately $10.7B across 32.8M SF and 563 properties at year-end 2025 (including unconsolidated joint ventures), with 89.6% occupancy in its medical office/outpatient portfolio. The company describes its facilities as primarily located on or near the campuses of acute care hospitals associated with leading health systems. In 2025 it disposed of 70 properties for approximately $1.1B at a 6.7% weighted-average cap rate.

Welltower outpatient medical portfolio sale. Welltower entered a definitive agreement on August 14, 2025 to sell a portfolio of 319 outpatient medical properties for approximately $7.2B, with net proceeds expected to total approximately $6.0B after a portion of gross proceeds is reinvested in a mandatorily redeemable preferred interest. The sale is now substantially closed: perWelltower's Q2 2026 10-Q, 311 properties had been disposed through June 30, 2026, with the remaining tranches expected to close by the end of 2026.

The MOB middle market. Beneath the public-REIT consolidation, a robust set of MOB-dedicated institutional platforms continues to build:Anchor Health Properties(which describes itself as focused exclusively on medical outpatient buildings and specialty healthcare facilities); Davis Healthcare Real Estate; Catalyst Healthcare Real Estate; Montecito Medical; Hammes Healthcare; Caddis; MedCraft; Rendina Healthcare; Pacific Medical Buildings.

The institutional landscape that emerges in 2026: large public healthcare REIT platforms with outpatient medical portfolios (Healthpeak/DOC and Healthcare Realty Trust), one seller in transition (Welltower, with its outpatient medical sale substantially closed as of mid-2026 and final tranches expected by year-end), an expanding institutional middle market (Anchor, Davis, Catalyst, Montecito, Hammes, Caddis, MedCraft, Rendina, Pacific Medical Buildings), and a life-company permanent debt market, which Deal A assumes at 5.40% fixed for a 10-year credit-MOB take-out.

Demand: Physicians, Outpatient Shift, and Supply

The institutional thesis for entering MOB in 2026 rests on a three-part demand backdrop intersecting with a structurally constrained supply pipeline.

Physician supply shortage. TheAAMC's Projections From 2021 to 2036forecast a US physician shortage of up to 86,000 by 2036. Roughly 42% of the clinical physician workforce is age 55 or older (20% age 65+, 22% age 55–64), implying a retirement-cycle that pulls capacity out faster than medical schools and residency programs can replace. In the Apers view, the demand-side consequence is that practices that remain operate at higher patient throughput per square foot, and the real estate hosting them retains pricing power. The succession-planning opportunity for the institutional MOB owner is the practice sale-leaseback as senior physicians retire and PE-backed platforms or hospital systems acquire the practice with the building separately disposed.

Outpatient migration. Care continues to migrate from inpatient to outpatient settings. Drivers: minimally invasive surgical techniques moving procedures from the inpatient OR to ambulatory surgery centers; patient preference for shorter recovery and out-of-hospital care; and hospital-system strategy directing elective volume to dedicated ambulatory facilities.

Supply. InRevistaMed's3Q2026 top-100-metro data, completions over the trailing twelve months were 11.28M SF, down 27.3% year over year and about 1.0% of the 1.11B SF inventory, while 25.2M SF (about 2.3% of inventory) was under construction. On the on-campus side, new supply depends on hospital-system development partners, who take the lead on most new on-campus build on extended lead times. Per theULI / PwC Emerging Trends in Real Estate 2026 property type outlook, medical office is highly rated, with strong buying conditions in the survey's buy-hold-sell recommendations.

The traditional office contrast. CBRE's Q2 2026 figures put the average MOB sale price at $307/SF, 57% higher than the $196/SF average for traditional office buildings. In the Apers view, MOB did not experience the flight-to-quality compression that pressured Class B/C traditional office, the WFH demand destruction that hollowed CBD office, or the maturity-wall refinancing distress at scale. The same ULI / PwC outlook rates medical office highly while central city and suburban office are among the lowest-rated subsectors. Thetrophy Class A vs Class B repositioning articlewalks the conventional-office bifurcation that MOB sidestepped.

The 2026 thesis: modest supply growth, demographically-driven demand growth, an outpatient migration that the Apers view treats as structural, an institutional capital base that includes large public platforms plus an expanding institutional middle market, and a permanent debt market that Deal A assumes is open at 5.40%. RevistaMed's preliminary 3Q26 cap-rate read points to marginal expansion, so the Apers working view is to underwrite stable cap rates rather than assume further compression.

Two Worked Deals - Deal A and Deal B

The two-deal worked example carries the framework through end-to-end. Deal A is single-tenant credit MOB. Deal B is multi-tenant off-campus MOB. Both are illustrative constructs, not specific transactions, shaped like the opportunities that reach institutional acquisitions desks.

The two deals together illustrate the bifurcation in operation. Deal A is a credit instrument: the lease is the asset, the underwriting is the CTL framework, the cap-rate range sits in the tighter half of the table, and the return profile is a steady escalator-plus-amortization return, underwritten with 40 bps of exit-cap decompression. Deal B is an operational portfolio: the rent roll is the central artifact, the underwriting is rent-roll-plus-WALT-plus-retention-plus-CAM- reconciliation, the cap-rate range is the mid-tier, and the return profile is operational lease-up plus mark-to-market plus disciplined exit. Both belong in an institutional MOB allocation. The institutional discipline is to know which deal you have on the desk and apply the right framework. TheIRR calculator and formula articlewalks the levered return mechanics; theTI/LC and effective rent articlewalks the multi-tenant TI/LC reserve discipline that Deal B's rollover ladder demands.

Six Mistakes Practitioners Make

• Treating MOB as a single asset class. The most common analyst mistake. The sector bifurcates into two disciplines with different cap-rate ranges, different risk concentrations, different buyer pools, and different debt markets. Apply the single-tenant credit framework to a multi-tenant rent roll and you miss the rollover ladder; apply the multi-tenant operational framework to a single-tenant credit lease and you over-engineer the underwriting on an asset that is being priced as a credit instrument. The first IC question on any MOB deal is which side of the bifurcation the asset sits on.

• Computing WALT one way. Many published walkthroughs and sponsor offering memoranda quote a single WALT number, usually rent-weighted. The institutional discipline is to compute and report both rent-weighted and space-weighted on the same rent roll. A material spread between the two surfaces anchor concentration that hides small-tenant rollover risk; a narrow spread confirms the rent roll is balanced. Always compute both. The two-line spreadsheet formula is trivial; the diagnostic value is high.

• Missing the on-campus/off-campus distinction. Treating on-campus and off-campus MOB as comparable assets and applying a sector-average cap rate to both is a deal-stage error. In the Table 4 synthesis, the on-campus premium versus off-campus Class A is 50–100 basis points in cap rate, about $8/SF in rent, and about 5 percentage points in stabilized occupancy. The trade-off is hospital subordination tail risk and ground-lease exit constraints - both of which should be priced in basis points, not glossed.

• Underwriting the parent-co guarantee at face. A lease "guaranteed by [Health System]" is not necessarily guaranteed by the rated parent. Read the guarantee document line by line: is the guarantee at the system level (the rated parent corporation), at the regional affiliate level (typically unrated), or at the local subsidiary level (an operating shell with no balance sheet)? The cap-rate difference between a system-level guarantee and a local-affiliate-only guarantee is 50–150 basis points; sponsors routinely market the asset on the brand recognition of the system and hide the affiliate-only nature of the guarantee in the disclosure schedules.

• Mistaking modified gross for NNN. Multi-tenant MOB is more frequently modified gross than NNN; single-tenant credit MOB is more frequently NNN or absolute net than modified gross. The lease structure determines who carries the inflation risk on operating expenses, who absorbs the capex pass-through, and how the institutional buyer underwrites the recovery ratio. The CAM reconciliation history is the artifact that proves the actual recovery on modified gross product; pull three years on every multi-tenant MOB deal. Thegross vs NNN expense stops articlewalks the lease-structure discipline that applies directly to MOB.

• Missing the hospital subordination on-campus. Where the MOB sits on a hospital ground-leased site, the MOB lease economics are subordinated to the hospital's continued operation. If the hospital files Chapter 11 or closes the campus, the on-campus MOB loses its tenant referral base, its physician traffic, and frequently the integrated services that anchored the property. Steward Health Care, Prospect Medical, and Hahnemann are the institutional reference cases for what this looks like in practice. Underwrite the hospital's credit and operating economics with the same rigor you apply to the MOB tenant credit - because in on-campus MOB, the hospital's credit becomes the MOB's credit.

From MOB Underwriting to Apers

The discipline above - the bifurcation framework, the WALT computation both ways, the on-campus differential, the credit-tenant lease framework, the eight-bucket cap-rate table, the two worked deals - is the institutional MOB underwriting workflow. Every step is reproducible in Excel from the inputs disclosed on this page and the cited institutional sources. The math is straightforward; the document discipline (CTL lease read for Deal A; rent roll read for Deal B) is the workload that consumes the analyst's afternoon.

Apers compresses the document-and-modeling workload. The institutional acquisitions analyst opens the lease and the rent roll, hands them to the platform, and gets back the same Year 1 NOI, the same WALT computation, the same cap-rate-range calibration against the eight-bucket framework, and the same levered-IRR projection - in minutes rather than hours, with the same defensible audit trail.

Related Articles

• Office Underwriting: TI/LC, Free Rent, and Effective Rent - the multi-tenant TI/LC reserve and effective-rent mechanics that Deal B's rollover ladder demands.
• Office Lease Analysis: Gross vs NNN and Expense Stops - the lease-structure discipline that applies directly to single-tenant credit MOB and multi-tenant MOB.
• Trophy / Class A vs Class B Office Repositioning - the office subset bifurcation MOB did not need; the contrast that draws generalist office capital into healthcare.
• Cap Rate Calculator and Formula - the basic NOI / value mechanics that the eight-bucket MOB framework calibrates against.
• IRR Calculator and Formula for Real Estate - the levered return mechanics for Deal A and Deal B.

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