Middle market CLOs

Does your product fit here?

Middle market CLOs (MM CLOs) hold loans to borrowers with EBITDA typically between $10M and $75M. The defining characteristics: smaller obligors, higher yields, less liquid underlying loans, tighter lender protections, and manager-dependent sourcing. If you’re evaluating a CLO backed by loans to companies that wouldn’t qualify for the broadly syndicated loan market, you’re in the right place.

Products that fit here:

Classic middle market loans: Direct loans to companies with $15-50M EBITDA, typically first lien senior secured, floating rate, originated by BDCs, direct lenders, or specialty finance companies. Golub, Blue Owl, Ares, Monroe.
Lower middle market loans: $10-25M EBITDA borrowers, often with sponsor backing (PE), higher spreads (SOFR + 550-700+). More covenant-heavy, less liquid, higher defaults but also higher yields.
Core middle market: $25-75M EBITDA, more institutional, spreads SOFR + 450-600. This is the sweet spot for most MM CLOs.
Upper middle market / “crossover”: $50-100M EBITDA, sits between MM and BSL, increasingly competitive pricing. Some of these loans trade on secondary markets.

What does NOT fit here:

Broadly syndicated loans (BSL): EBITDA typically $100M+, traded on secondary markets via LSTA, lower spreads (SOFR + 300-450), more standardized (often covenant-lite) terms. See Broadly Syndicated Loan CLOs.
Private credit fund (unleveraged): If you’re running a direct lending fund without CLO financing, you’re a capital provider, not a CLO issuer. The evaluation framework is different.
Unitranche or mezzanine funds: Different capital stack position, different risk profile. Typically held in funds, not CLOs.
Venture debt: Very different collateral, not MM CLO collateral.

Edge cases

“Crossover” or “hybrid” CLOs: Some managers run deals with a mix of BSL and MM loans (e.g., 60% MM, 40% BSL). These are typically treated as MM CLOs if majority middle market by par. The blended portfolio may have better diversity but also blended economics.

Private credit CLOs: Marketing term for MM CLOs. Same product, different label.

Club deals that become liquid: A loan originated as MM can trade later if the borrower grows or gets refinanced in the BSL market. Treatment depends on characteristics at origination for CLO eligibility purposes.

How the market segments MM CLO managers

Tier	Characteristics	Examples
Tier 1 / Established	5+ MM CLOs, $3B+ AUM in MM CLOs, track record through credit cycle (2020, 2022)	Golub Capital, Blue Owl, Ares, Monroe, Crescent
Tier 2 / Emerging	2-4 MM CLOs, $500M-3B AUM, established direct lender but newer to CLO format	New Mountain, Varagon, WhiteHorse
Tier 3 / First-time	First or second MM CLO; requires significant diligence on sourcing and workout capability	Newer BDCs, regional direct lenders

The manager tier matters for pricing. Tier 1 managers price AAA tranches 10-25 bps tighter than Tier 3. The difference in equity returns between a well-run and poorly-run MM CLO can be 500-1000 bps of IRR.

Market benchmarks and comps

MM CLO market size

The MM CLO market is roughly $90-110B outstanding, compared to $1T+ for BSL CLOs. Annual issuance runs $15-25B per year, with 2021 being a peak year. Average deal size is $350-500M, smaller than BSL CLOs ($500M-1B+).

Performance benchmarks

Metric	MM CLO Typical	BSL CLO Comparison
Default rate (annual)	1.5-3.5%	1.0-2.5%
Recovery rate (1L senior secured)	60-70%	65-75%
Loss rate (CDR x severity)	0.5-1.5% annual	0.3-0.9% annual
Weighted average spread (portfolio)	SOFR + 525-650	SOFR + 350-450
WARF	2800-3200	2600-2900
Diversity score	40-60	80-120

MM CLOs have higher default rates than BSL CLOs, but also higher portfolio spreads. The question is whether the spread premium compensates for the additional risk. Historically, it has, but with less margin for error.

MM CLO liability spreads (2024)

Tranche	New Issue Spread	Enhancement Level
AAA	SOFR + 175-220	37-42%
AA	SOFR + 250-325	27-32%
A	SOFR + 325-400	20-25%
BBB	SOFR + 450-575	13-17%
BB	SOFR + 700-900	7-10%
Equity	12-18% IRR target	0% (first loss)

Illustrative pricing. See pricing disclaimer.

Compared to BSL CLOs, MM CLO liabilities price 25-75 bps wider at each rating level. This reflects lower portfolio diversity, less liquid collateral, and smaller obligor sizes.

What “good” performance looks like

Default rates below 2% annually for a seasoned portfolio (3+ years)
WARF stable or improving during reinvestment period
Junior OC cushion maintained above 3-4%
No CCC bucket breach (typically 7.5% limit)
Manager able to trade out of stressed credits before they default
Portfolio spread maintained within 25 bps of target during reinvestment
No trigger events or cash trapping

Red flag performance benchmarks

WARF deteriorating by 100+ points in 12 months
CCC concentration above 6% and approaching the 7.5% limit
Junior OC test failing or cushion eroding below 2%
More than 2-3 defaults in a single year for a $400M CLO
Inability to reinvest prepayments at similar spreads (spread compression)
Recovery rates on defaults below 55%
Top 10 obligor concentration drifting above 30%

What lenders and investors focus on

1. Manager quality and sourcing capability

This is the single most important factor in MM CLO investment. Unlike BSL CLOs where loans are commoditized and managers are largely interchangeable, MM CLO performance is highly manager-dependent.

Sourcing matters because:

Direct origination gives the manager more control over terms (covenants, pricing, documentation)
Club deal participation means sharing deal flow with other lenders and less control
Secondary purchases are typically available only for stressed credits or at premium prices

What to evaluate:

What percentage of loans are directly originated vs. club deals vs. secondary purchases?
How many sponsor relationships does the manager have? Are they repeat relationships?
What is the funnel: how many deals does the manager see, how many does it bid on, how many does it win?
What is the underwriting track record by vintage? Do older vintages perform in line with projections?

Team stability: MM CLO performance depends on relationship-based deal flow. If senior originators or portfolio managers leave, deal flow and credit selection may suffer. Check tenure, compensation structure, and succession planning.

2. Portfolio credit quality and diversity

MM CLO portfolios are inherently less diversified than BSL CLOs. A $400M MM CLO might have 40-60 obligors, compared to 150-300 for a comparable BSL CLO. This concentration means individual credit mistakes have larger impact.

Key metrics:

WARF: Weighted average rating factor. MM CLOs typically run 2800-3200. Above 3200 is a flag.
Rating distribution: What percentage is B2 vs. B3 vs. CCC? B3 and worse concentration above 15% is concerning.
Industry diversification: No single industry should exceed 10-12%. Healthcare, software, and business services are common large exposures.
Obligor concentration: Top 10 obligors typically represent 20-25% of portfolio. Above 30% is high.
Sponsor quality: What percentage is PE-backed? Non-sponsored credits have historically higher default rates.

3. Covenant quality

MM loans typically have tighter covenants than BSL loans, but covenant quality has eroded over time. You need to understand what you’re actually getting.

Maintenance covenants: Tested quarterly regardless of borrower action (leverage, coverage, capex). Gold standard.
Springing covenants: Only tested if revolver is drawn above a threshold. Provides some protection but less than maintenance.
Incurrence-only covenants: Only tested when borrower takes an action (more debt, dividend, acquisition). Weakest protection.

For a MM CLO, you want 60%+ of the portfolio with maintenance or springing covenants. If the majority is incurrence-only, the “middle market” label may not mean “better protected.”

4. Structural protections and OC cushion

The OC test cushion is your buffer against losses. At issuance, a typical MM CLO has 4-6% junior OC cushion. This means the portfolio can decline 4-6% in value (through defaults, CCC haircuts, or trading losses) before the junior OC test fails and equity distributions stop.

What to watch:

Current cushion vs. issuance: Has it grown or shrunk?
Trajectory: Is it stable, improving, or deteriorating?
CCC haircut impact: How much of the current cushion is being consumed by CCC haircuts?

A junior OC cushion below 3% should trigger heightened monitoring. Below 2% is a red flag.

5. Liquidity and trading constraints

MM loans are illiquid. Bid-ask spreads can be 2-5 points, compared to 0.5-1 point for BSL. This has implications:

Active management is harder: Trading out of a stressed credit costs more and may not be possible at any price.
Mark-to-market volatility: Even if the loan performs, marks can swing significantly on limited trading.
Realized losses: If the manager needs to sell, the discount can exceed the credit loss.

Review the trading history: has the manager been actively trading? What were the realized gains or losses? Managers who trade actively in illiquid markets can either add value or destroy it.

Typical structures used

Standard MM CLO structure

Parameter	Typical Range
Deal size	$350-500M
Number of tranches	6-8 (AAA through equity)
Reinvestment period	3-5 years
Non-call period	1-2 years
Legal final maturity	10-13 years from closing
Number of obligors	40-60

Capital stack

Tranche	Typical Size	Enhancement
AAA	55-62% of deal	38-45%
AA	8-12%	27-33%
A	6-8%	20-26%
BBB	5-8%	13-18%
BB	3-5%	8-12%
Equity	7-10%	0% (first loss)

Equity economics

Equity is first loss and receives residual cash flows after all rated note interest, fees, and OC test cures. Target returns:

IRR target: 12-18%
Cash-on-cash yield: 8-15% depending on portfolio spread and defaults
Return drivers: Portfolio spread minus liability cost, minus fees, minus losses
Risk: Equity can be wiped out in severe stress (2008-style scenario)

A $400M MM CLO with 8% equity ($32M) generating 14% IRR over a 5-year reinvestment period produces roughly $22-25M of total return. However, a single vintage with 5%+ defaults can eliminate most of that return.

Warehouse-to-CLO path

Most MM CLO issuers use a warehouse facility to accumulate loans before CLO pricing:

Warehouse advance rate: 70-85% of eligible loans
Warehouse spread: SOFR + 175-275 bps
Warehouse period: 6-18 months
Ramp trigger: CLO typically priced when 60-80% ramped

The warehouse phase is where the portfolio is built. Managers who can ramp quickly (within 9-12 months) while maintaining credit quality have an advantage. Extended warehouse periods (18+ months) may signal sourcing difficulties.

Asset-class-specific structural features

OC and IC tests

Senior OC test: Measures par coverage of senior notes (AAA/AA). If the portfolio par value divided by senior note principal falls below the threshold (typically 118-125%), interest is diverted from mezzanine to pay down senior principal. Rarely fails except in severe stress.

Junior OC test: Measures par coverage of all rated notes. If it fails, cash is trapped and equity distributions stop. The junior OC cushion (current ratio minus threshold) is the key metric for equity investors. Typical threshold is 102-106%.

Interest coverage (IC) test: Measures portfolio interest income vs. rated note interest expense. Rarely binding for MM CLOs given high portfolio spreads.

CCC treatment and haircuts

The CCC bucket is one of the most important structural features in MM CLOs:

CCC limit: Typically 7.5% of portfolio
Excess CCC treatment: Loans rated CCC+ or below that exceed the 7.5% bucket are valued at market price (not par) in the OC calculation
CCC drag: Even before defaults, a rising CCC bucket can erode OC cushion significantly

Example: A $400M CLO at the 7.5% CCC limit has $30M in CCC loans. If $10M additional loans get downgraded to CCC (now $40M total, or 10% of portfolio), the $10M excess must be marked to market. If those loans are trading at 80, the OC calculation takes a $2M haircut, reducing junior OC cushion by roughly 50 bps.

Reinvestment criteria

During the reinvestment period, the manager can reinvest principal proceeds into new loans subject to criteria:

Minimum spread: Floor (e.g., SOFR + 400) to maintain portfolio economics
Maximum WARF contribution: New loan cannot increase portfolio WARF
Concentration limits: Industry (10-12%), obligor (2-2.5%), CCC (7.5%)
Collateral type: Typically 90%+ first lien senior secured; 5-10% second lien permitted
No distressed purchases: Cannot buy loans below 80% of par

Trading and discretionary sales

The manager has discretion to sell loans to manage credit risk:

Credit risk sales: Manager can sell loans that have deteriorated or are on credit watch
Discretionary sales: Some structures allow limited discretionary trading (e.g., 10% of portfolio per year)
Gain/loss treatment: Trading gains increase OC; losses reduce it
Discounted purchases: If manager buys a loan at 90, it counts at 90 (not par) in OC

Managers who trade actively and well can add 100-200 bps to equity returns. Managers who trade poorly can destroy value.

Non-call and call provisions

Non-call period: 1-2 years post-closing; equity cannot call the deal during this period
Post-non-call: Equity can call the deal at par plus accrued (refinance at tighter spreads or liquidate)
Clean-up call: Typically when portfolio balance falls below 10-20% of original; allows orderly wind-down
Make-whole: Some deals have make-whole premiums during non-call; rare in MM CLOs

Call optionality is valuable. If spreads tighten after closing, the equity holder can refinance the liabilities and capture the spread compression. If spreads widen, the equity holder can hold to maturity.

Rating agency treatment

Moody’s approach

Moody’s builds an independent loss model using idealized default probabilities by rating category. For MM CLOs, they apply several adjustments:

WARF stress: Higher stress multiples for MM due to smaller obligor universe and lower diversity
Diversity score: MM CLOs have lower diversity (40-60 vs. 80-120 for BSL), requiring more subordination
Manager adjustment: Moody’s rates CLO managers and adjusts required subordination based on track record
Recovery assumptions: 60-65% for first lien MM loans (vs. 65-70% for BSL)

Typical Moody’s Aaa subordination for MM CLOs: 38-43%.

S&P approach

S&P uses the CDO Evaluator model with obligor-specific ratings:

Correlation assumptions: Industry and obligor correlation drive loss distribution
Recovery assumptions: 60-65% for MM first lien, scenario-dependent
Concentration penalties: Higher subordination for concentrated portfolios
Manager qualitative review: Incorporated but less formal than Moody’s

Typical S&P AAA subordination: 37-41%.

Fitch approach

Fitch uses the Portfolio Credit Model (PCM):

Default assumptions: Higher for unrated obligors (common in MM)
Recovery assumptions: Asset-specific, typically 55-65% for MM
Stress scenarios: Multiple economic scenarios tested

Typical Fitch AAA subordination: 38-42%.

KBRA and DBRS

Both agencies are growing their MM CLO presence:

More flexible with first-time managers
Competitive with big three on subordination levels
Often used as second rating alongside Moody’s or S&P

Typical enhancement levels

Rating	Subordination	Total CE (incl. OC)
AAA	37-43%	40-46%
AA	27-32%	30-35%
A	20-25%	23-28%
BBB	13-17%	16-20%
BB	7-10%	10-13%

Enhancement levels for MM CLOs are 3-5% higher at each rating level compared to BSL CLOs, reflecting the additional risk from concentration and illiquidity.

Diligence focus areas

Manager diligence

Track record: Request vintage-level default rates for all prior CLOs and direct lending funds. Compare to MM CLO index benchmarks. Ask for loss attribution: which sectors, sponsors, deal types drove losses?

Team: Get bios for senior originators, portfolio managers, and workout specialists. What is average tenure? Have there been departures in the last 2 years? What are the key person provisions in the CLO docs?

Sourcing: What percentage of loans are from direct origination vs. club deals vs. secondary? How many sponsor relationships are active? Is deal flow concentrated in a few relationships?

Underwriting process: How is the credit committee structured? What is the approval process? How are exceptions tracked and reported? What percentage of deals are exceptions?

Workout capability: What is the historical recovery rate on defaulted loans? Is there a dedicated workout team or is it outsourced? What is the typical workout timeline?

Conflicts: How are deals allocated between CLO and non-CLO vehicles? Is there a formal allocation policy? Has there been any regulatory inquiry or investor complaint related to allocation?

Portfolio diligence

Loan tape analytics: Request the full loan tape with obligor name, industry, EBITDA, leverage, spread, maturity, rating, and covenant type. Run standard stratifications.

Credit quality: Calculate WARF, rating distribution, CCC concentration. Compare to manager’s other CLOs and to market benchmarks.

Covenant analysis: What percentage of loans have maintenance covenants? Springing? Incurrence-only? How does this compare to manager’s stated strategy?

Top obligor review: Do deep credit review on top 10-15 names (typically 25-30% of portfolio). Are any on credit watch? Any covenant amendments in the last 12 months?

Stressed credits: What percentage of portfolio is on the manager’s internal watch list? Any restructurings or workouts in progress? Any expected downgrades?

Structural diligence

OC cushion: What is current junior OC cushion vs. closing level? What is the trajectory over the last 4-6 quarters? What drove any changes?

CCC headroom: How close is the portfolio to the 7.5% CCC limit? What is the haircut currently being applied to excess CCC?

Reinvestment period: How much time remains? If less than 2 years, the portfolio is entering the amortization phase and return profile changes.

Trading activity: Has the manager been actively trading? What were realized gains or losses? Were trades defensive (selling stressed credits) or opportunistic?

Documentation review

Key documents: indenture, collateral management agreement, collateral administration agreement.

Key provisions to review:

Reinvestment criteria (spread floor, WARF limit, concentration limits)
Trading restrictions (discretionary sale limits, credit risk sale definitions)
Manager termination provisions (for cause, without cause, replacement mechanics)
Fee structure (management fee seniority, subordination of incentive fee)
Risk retention compliance (who holds, what form, where held)

Active participants

Tier 1 MM CLO managers

Golub Capital: Pioneer in MM CLOs. 30+ deals, $50B+ AUM. Deep sponsor relationships, strong track record.
Blue Owl / Owl Rock: Major direct lender with multiple MM CLO programs. Large origination platform.
Ares Management: One of the largest direct lenders globally. Active MM CLO issuer with long track record.
Monroe Capital: Lower middle market focus. Established track record through multiple cycles.
Crescent Capital: Long track record in MM CLOs. Core middle market focus.
Churchill Asset Management (Nuveen): Upper middle market focus. Large balance sheet.
Antares Capital (BC Partners): One of the largest MM lenders. Frequent CLO issuer.

Tier 2 / emerging managers

New Mountain Capital: Growing CLO program alongside flagship PE and credit funds.
Varagon Capital (AIG): Insurance-affiliated direct lender. Building CLO track record.
WhiteHorse Capital: Middle market specialist. Several CLOs issued.
Benefit Street Partners (Franklin Templeton): Active direct lender, building CLO presence.
TCW: Established credit manager building MM CLO presence.

Banks providing warehouse financing

Major banks with MM CLO warehouse programs:

JPMorgan, Citi, Goldman Sachs, Morgan Stanley, Bank of America
Barclays, Deutsche Bank, UBS (formerly Credit Suisse)
Natixis, Societe Generale, BNP Paribas

Typical warehouse terms: $200-500M facility, SOFR + 175-275 bps, 12-18 month revolving period, 70-85% advance rate.

CLO note investors

AAA buyers:

Insurance companies (MetLife, Prudential, Principal)
Bank treasury desks
Japanese regional banks (significant MM CLO AAA buyers)
Money market-adjacent funds

Mezzanine (AA-BBB) buyers:

Insurance companies (larger allocations here)
Pension funds
CLO-focused funds (CIFC, Sound Point, Napier Park)
Hedge funds

BB and equity buyers:

CLO equity funds (Ellington, CIFC, Napier Park, Sculptor)
Hedge funds
Manager balance sheets (risk retention)
Family offices (limited)

Structuring banks / underwriters

Primary CLO structuring desks:

Morgan Stanley, Citi, Barclays, JPMorgan, Goldman Sachs
Bank of America, UBS, Deutsche Bank
Wells Fargo, RBC, Jefferies (smaller deals)

Law firms

Manager counsel: Ropes & Gray, Latham & Watkins, Simpson Thacher, Kirkland & Ellis, Proskauer Underwriter counsel: Cadwalader, Milbank, Davis Polk, Sidley Austin Trustee counsel: Seward & Kissel

Red flags and off-market characteristics

Manager red flags

First-time CLO manager without significant direct lending track record: If the manager hasn’t managed credit through a cycle, you’re taking underwriting risk in addition to credit risk.
Key person departures without replacement: Senior originator or PM departures can disrupt deal flow and credit selection.
Regulatory investigation or compliance issues: Any SEC, DOL, or state-level inquiry is a flag.
High turnover in credit/origination team: More than 20% annual turnover suggests cultural or compensation issues.
Conflicts between CLO and other funds: If the manager also runs SMAs, co-investment vehicles, or other CLOs, ask how deals are allocated. Preferential allocation to other vehicles would harm CLO investors.
Declining AUM or inability to raise new capital: May signal investor concern about track record or strategy.

Portfolio red flags

WARF above 3200 or deteriorating rapidly: WARF above 3200 suggests the portfolio is drifting into weaker credits. Deterioration of 100+ points in 12 months is a warning sign.
CCC concentration above 6% and rising: Approaching the 7.5% limit creates OC haircut risk. If CCC concentration is already 6%+ with 3+ years of reinvestment remaining, the manager has limited room for further downgrades.
Top 10 obligor concentration above 30%: High single-name risk. One or two defaults could significantly impair equity.
Single industry above 15%: Industry concentration creates correlation risk.
More than 10-15% of portfolio on credit watch: Suggests credit selection problems.
Recovery rate trending below 55% on realized defaults: Recovery expectations may be too optimistic.
Significant second lien or unsecured exposure (above 5%): These positions have 30-40% recovery, not 60-70%.

Structural red flags

Junior OC cushion below 2% or declining: Equity is at risk of cash trapping. Below 2% is a red flag; below 1% is critical.
Reinvestment period expired with limited trading flexibility: Portfolio will amortize, reducing equity cash flow. Limited trading means manager can’t manage credit risk.
High fee structure: Management fee above 50 bps or incentive fee above 20% reduces equity economics.
Unusual provisions: Manager-friendly liquidation terms, weak replacement provisions, or unusual consent thresholds warrant scrutiny.
Risk retention structure concerns: Risk retention not clearly documented or held in a structure that may not comply with EU/UK rules.

Market / pricing red flags

New issue spreads significantly wider than comps: If a manager is pricing 25+ bps wide of comparable deals, investors are signaling concern about manager or portfolio.
Unable to place mezzanine tranches: If the manager retained mezzanine tranches at pricing, the market may have concerns about credit quality.
Equity IRR target above 20%: Suggests distressed pricing, aggressive portfolio assumptions, or both.
Repeated resets or refinancings without economic rationale: May signal underlying portfolio problems being masked by liability restructuring.

Important: The combination of first-time manager + high WARF + concentrated portfolio + tight OC cushion is the classic pre-impairment profile. When you see three or more of these factors together, the risk is elevated even if current cash flows look fine.

Off-market characteristics that signal caution

Portfolio WAL significantly shorter than reinvestment period: Suggests inability to source longer-dated loans at target spreads.
High percentage of club deals vs. direct origination: Less control over terms and pricing; may signal weak sponsor relationships.
Concentration in cyclical industries above peer levels: Energy, retail, and hospitality concentration amplifies recession risk.
Manager also runs a distressed fund: Potential conflict in workout situations. Ask how the manager handles loans that migrate from performing to distressed.
Significant overlap between CLO portfolio and manager’s other funds: May indicate allocation issues or lack of deal flow diversity.