Green Bonds and Sustainability-Linked Loans in 2026: What Lenders and Investors Now Verify

Two sustainable debt markets have moved in opposite directions this year, and the contrast is instructive.

Green bonds got a supervised label. Since 22 June 2026, anyone providing an external review for a European Green Bond must be registered with the European Securities and Markets Authority, and at the point the register opened there were five such firms.

Sustainability-linked loans went the other way. Issuance fell through 2025 and headwinds continued into 2026 as borrowers and lenders alike questioned the credibility of the label, while the governing principles tightened and key recommendations became requirements.

One market is being professionalised by regulation. The other is being disciplined by the market itself. Both now verify harder than they did two years ago, and the things they verify are specific.

The EuGB Reviewer Regime Hardened In June

Regulation (EU) 2023/2631 established the European Green Bond Standard. It was published in the Official Journal on 30 November 2023, entered into force on 21 December 2023 and applied from 21 December 2024. The label is voluntary and coexists with market standards including the ICMA Green Bond Principles.

For its first 18 months of application, external reviewers operated under a transitional regime. They could provide services on the basis of notification to ESMA, with best efforts compliance against the substantive requirements. That window ran from 21 December 2024 to 21 June 2026.

It has closed. From 22 June 2026, reviewers must be formally registered with ESMA, and firms that operated under the transitional notification regime must cease external review activity unless they completed full registration. ESMA published the register on the same day, alongside a separate historical register recording who operated during the transitional period and when.

ESMA is the direct and exclusive supervisor. There is no national competent authority split, so the same register and rules apply whether the issuer sits in Luxembourg, Ireland or anywhere else in the single market. Registered reviewers must meet requirements covering senior management accountability, analytical capability, robust and transparent methodologies, internal controls and conflict of interest management. ESMA can conduct on-site inspections, examine records, interview individuals, impose fines and periodic penalty payments, and temporarily or permanently remove a reviewer's rights.

Five Registered Reviewers

At the register's publication on 22 June 2026, five external reviewers were registered, including entities of Moody's, Sustainable Fitch and S&P Global Ratings.

That number deserves attention from any issuer planning a European Green Bond. The registration fee alone is 40,000 euro, and the regulatory standards are substantial, so the barrier to entry is real. A small pool of supervised providers means capacity constraints, pricing power and potential timing difficulties around peak issuance windows.

Third country reviewers have a route. In the absence of an equivalence decision, a reviewer with a legal representative established in the European Union may apply for recognition, under rules specified in a delegated regulation adopted in March 2026.

The practical instruction is simple. Confirm your intended reviewer's registration status on ESMA's register before you appoint, and build the appointment into your issuance timetable earlier than you would have done under the transitional regime.

What An EuGB Issuer Must Produce

External review attaches at three points: pre-issuance, post-issuance, and where applicable the impact report.

Pre-issuance, the issuer publishes a factsheet setting out how proceeds will be used, which is subject to review. Post-issuance, allocation reports document where the money actually went, again subject to review. The core substantive requirement is alignment of proceeds with the EU Taxonomy, with a flexibility pocket for a limited proportion of proceeds.

The Level 2 framework is now largely complete. Delegated regulations adopted in April 2025 cover voluntary post-issuance disclosure templates for bonds marketed as environmentally sustainable and for sustainability-linked bonds, the procedure for ESMA fines, and the fee structure. Implementing regulations cover registration application forms and, from July 2026, the procedure for notifying material changes to registration information. The Commission has issued guidance on use of proceeds, disclosure requirements and external reviews, and has updated its guidance on allocating proceeds to capital expenditure incurred before issuance.

Note the templates for sustainability-linked bonds. Even outside the EuGB label, the regulation created voluntary disclosure templates that shape market expectations for what an SLB issuer discloses.

Why The SLL Market Is Contracting

Sustainability-linked loan issuance decreased in 2025 and is expected to continue facing headwinds, with borrowers and investors increasingly questioning the product's credentials. The drivers are worth naming precisely, because they explain what lenders now test.

Greenwashing concern attached to the label itself. The reputational calculation has inverted. An SLL with weak targets is now a liability rather than a credential, because the label invites scrutiny that an unlabelled facility does not.

Immaterial KPIs. Where the chosen metric is peripheral to the borrower's actual sustainability impact, the structure looks decorative.

Unambitious SPTs. Targets representing business as usual, or trajectories the borrower would have met regardless, undermine the premise that pricing should reward performance.

Small margin adjustments. Where the ratchet is a couple of basis points, the incentive is symbolic and the documentation cost is not.

By contrast, use of proceeds labels are expected to grow, supported by investor demand for transparency and clearer regulatory frameworks, and transition loans may pick up following the Transition Loans Guide published by the LMA, LSTA and APLMA in late 2025.

KPI Selection: What Lenders Test

The Sustainability-Linked Loan Principles, published by the LMA, APLMA and LSTA, organise around five core components. KPI selection is the first, and three tests apply.

Relevance and materiality. KPIs must be relevant and material to the borrower's overall business, operations and sustainability strategy. A retailer selecting a water metric while its emissions profile dominates its impact will be challenged.

Measurability on a consistent methodology. The metric must be quantifiable on a consistent methodological basis over the life of the facility. Metrics whose definition shifts, or which depend on estimation methods the borrower can change, fail this.

External benchmarkability. KPIs must be capable of benchmarking against external references such as industry standards or scientifically developed standards, so that ambition can actually be evaluated. A metric with no external comparator cannot be assessed for ambition, only for movement.

A practical note on social KPIs. Gender equality metrics such as the percentage of women in management are frequently used because they are more quantifiable and trackable than most social indicators. That makes them defensible, but it also means lenders will test whether the metric was chosen for materiality or for measurability.

SPT Calibration And The Shift From Should To Shall

The 2025 updates to the Sustainability-Linked Loan Principles changed the register of several provisions, replacing should with shall. Some of those changes codified existing practice, but the signal matters.

SPTs shall be ambitious, representing a material improvement in the respective KPIs. This moved from recommendation to requirement. In most transactions it was already treated as non-negotiable, but the change removes the argument.

Post-signing verification shall be conducted by a qualified external reviewer with relevant expertise. Also moved from should to shall. Annual verification of performance against SPTs by a qualified independent party is now the stated requirement rather than good practice.

Reporting frequency requirements also shifted, and these may represent a more substantive change than the ambition and verification provisions, since they were less uniformly applied in practice.

On calibration mechanics, the principles recommend an annual SPT for each KPI, for each year of the loan term. Calibration should reference the borrower's own historical performance, peer benchmarks, and science-based or regulatory trajectories where they exist, with the target representing improvement beyond what the trajectory would deliver anyway.

Sleeping SLLs And Recalibration

Two structural issues attract particular scrutiny.

A sleeping SLL is a facility documented as sustainability-linked before KPIs and SPTs have been agreed. The principles now require the borrower to provide a clear rationale for why KPIs and SPTs cannot be set pre-origination, to disclose its existing sustainability strategy to lenders, and to agree a backstop date by which targets will be set, subject to a maximum of 12 months post-origination. Awakening the facility should require all-lender consent, with guidance on appropriate lower thresholds where unanimity is impracticable.

Recalibration is the other. The LMA updated its sustainability-linked loan provisions in August 2026, with amendments intended to balance lender interests in preventing greenwashing against borrower interests in retaining flexibility where business circumstances genuinely change. Acquisitions, disposals and strategic shifts can render a KPI framework unworkable through no fault of the borrower, and documentation that cannot accommodate that produces either a meaningless target or a default.

Borrowers with existing facilities should review whether their KPI and SPT framework survives corporate change, assess the robustness of their reporting and verification processes, confirm that documentation addresses recalibration events and future target setting, and check publicity and disclosure obligations attaching to the financing.

An Underexamined Conflict

One structural issue in sustainability-linked products deserves more attention than it gets.

Where a lender's return rises if the borrower misses its targets, the incentive structure is not straightforwardly aligned. A lender could in principle be content with targets the borrower is likely to miss, since missed targets mean higher interest payments. The mirror problem arises where a party structuring the deal has an interest in the outcome.

There is also a syndication timing issue. Where KPIs are agreed between the borrower and a sustainability coordinator before being shared with the broader syndicate, other lenders may lack time to properly assess the metrics before committing.

Neither problem is fatal, and good governance addresses both. But they explain why external verification has moved from recommendation to requirement, and why syndicate members increasingly want KPI discussions earlier.

Where Greenwashing Scrutiny Bites

Three enforcement vectors now apply to sustainable debt claims, and they operate independently of the loan or bond documentation.

Financial regulation. In the UK, the FCA's anti-greenwashing rule applies to any sustainability claim a regulated firm makes about a product or service, and marketing a facility as sustainability-linked is such a claim. The four tests are that claims be correct and capable of substantiation, clear, complete, and fairly compared.

Consumer and competition law. Environmental claims made publicly attract scrutiny under consumer protection and competition frameworks, with enforcement powers strengthening in several jurisdictions.

Disclosure regulation. Where a borrower or issuer publishes sustainability claims in regulated reporting, those claims sit within the disclosure liability framework applying to that reporting.

The practical exposure is that a weak SPT is not merely a commercial disappointment. If the transaction was publicised as evidence of sustainability commitment, and the target turns out to have been undemanding, the publicity is the exposure rather than the loan.

What Issuers And Borrowers Should Do

For EuGB issuers, confirm reviewer registration on ESMA's register before appointment, build the appointment earlier into your timetable given the small pool, and ensure your taxonomy alignment evidence is assembled before the pre-issuance review rather than during it.

For SLL borrowers, test each KPI against materiality, consistent measurability and external benchmarkability, and be prepared to defend why a chosen metric is the right one rather than the available one.

Calibrate SPTs against an external trajectory, not against your own baseline alone. The question a reviewer asks is whether the target represents improvement beyond what would have happened anyway.

Budget for annual external verification, which is now a requirement rather than a recommendation under the principles.

Review existing facilities for recalibration provisions, particularly if corporate activity is likely during the term.

Treat the publicity as the risk. A modest, well-evidenced target quietly documented carries far less exposure than an ambitious-sounding one announced loudly and missed.

For both, recognise that the direction of travel is the same even though the mechanisms differ. Green bonds are being verified by supervised reviewers under a regulated label. Sustainability-linked loans are being verified by lenders who have become considerably less willing to accept a weak structure. The era in which a sustainability label was self-certifying has ended in both markets.

Verification Checklist

1. For a European Green Bond, confirm your external reviewer appears on ESMA's register, since the transitional notification regime ended on 21 June 2026.

2. Note that only a small number of reviewers were registered at the register's publication, and plan appointment timing accordingly.

3. Budget for pre-issuance, post-issuance and, where applicable, impact report reviews.

4. Assemble EU Taxonomy alignment evidence before the pre-issuance review.

5. Check the Commission's updated guidance on allocating proceeds to capital expenditure incurred before issuance.

6. For third country reviewers, confirm whether recognition has been obtained under the March 2026 delegated regulation.

7. For an SLL, test each KPI for relevance and materiality to the overall business, consistent measurability, and external benchmarkability.

8. Set an annual SPT for each KPI for each year of the loan term.

9. Calibrate SPTs against external benchmarks and science-based or regulatory trajectories, not only your own historical baseline.

10. Note that the 2025 principles updates made ambitious SPTs and qualified external post-signing verification requirements rather than recommendations.

11. For a sleeping SLL, document the rationale for deferral, disclose your sustainability strategy to lenders, and agree a backstop date within 12 months of origination.

12. Review documentation for recalibration provisions following the LMA's August 2026 update, particularly where acquisitions or disposals are likely.

13. Assess syndication timing so that all lenders can evaluate KPIs before committing.

14. Apply anti-greenwashing discipline to any public statement about the financing, since the publicity carries more exposure than the facility.

Position as of September 2026. The EuGB external reviewer transitional regime ended on 21 June 2026 and ESMA's register was published on 22 June. The Sustainability-Linked Loan Principles are a voluntary framework, and the LMA updated its model provisions in August 2026. Confirm current requirements against ESMA, the relevant principles and your advisers, and take professional advice for your circumstances.

Sources

Commission Delegated Regulations (EU), European Securities and Markets Authority, European Commission, Loan Market Association, International Capital Market Association, FICC Markets Standards Board, Financial Conduct Authority anti-greenwashing rule, Arthur Cox, Slaughter and May, Pinsent Masons, Blakes, LexisNexis

This article is intended for general professional information and does not constitute legal, financial, or investment advice.