Green, Social and Sustainability-Linked Bonds: Use of Proceeds, the Greenium, Step-Up Coupons and the EU Green Bond Standard

What you will learn

• The difference between use-of-proceeds bonds (green, social, sustainability) and sustainability-linked bonds (SLBs).
• What the ICMA principles require and what a second-party opinion does and does not check.
• How to measure the greenium and a step-up coupon in euro terms on your own position.
• The core rules of the EU Green Bond Standard (European green bond, "EuGB"), applicable since December 2024.

Explanation

Bond basics such as coupon, yield to maturity and duration are covered in the course "Bonds & Fixed Income in Depth". Here we look only at what makes a bond "labelled".

Use-of-proceeds bonds. A green bond is an ordinary bond whose issuer promises to spend the proceeds on eligible green projects (renewable energy, clean transport, efficient buildings). A social bond finances social projects (affordable housing, healthcare, employment); a sustainability bond finances both. The bond is a claim on the whole issuer, not on the project: if the wind farm fails you are still repaid while the issuer is solvent, and if the issuer defaults the wind farm does not save you. Credit risk equals that of the issuer's conventional bonds of the same seniority.

The market standard is the voluntary Green Bond Principles of the International Capital Market Association (ICMA), with four components: use of proceeds, a project selection process, management of proceeds (tracking the money in a register) and reporting on allocation and, where possible, impact. Most issuers obtain a second-party opinion (SPO), which checks that the framework fits the principles; it does not audit whether the money was spent as promised. Post-issuance allocation reports do that, often with limited assurance.

Sustainability-linked bonds (SLBs). Proceeds are for general purposes; instead, the coupon is tied to a key performance indicator (KPI) with a sustainability performance target (SPT). If the target is missed, the coupon steps up, typically by 25 basis points (0.25 percentage points). The first SLB, issued by the Italian utility Enel in September 2019 (USD 1.5 billion), carried a 25 basis point step-up if renewables did not reach 55 % of installed capacity by the end of 2021. Critics note three weaknesses: targets close to existing plans, step-ups small relative to total interest cost, and test dates late in the bond's life so the penalty applies to only one or two coupons.

The greenium. When demand for labelled bonds exceeds supply, a green bond trades at a slightly lower yield than the issuer's otherwise identical conventional bond. This yield gap is the greenium; for the investor it is a cost. Studies find it small, a few basis points, and unstable: a Banque de France note of December 2024 found the average greenium of French and European issuers had shrunk after 2021 and largely disappeared in 2024. Check current data before assuming one exists.

The EU Green Bond Standard. Regulation (EU) 2023/2631 created the voluntary "European green bond" (EuGB) label, applicable from 21 December 2024. As of 2026: at least 85 % of proceeds must go to EU-taxonomy-aligned activities (lesson 6), with a "flexibility pocket" of up to 15 % for activities without technical criteria yet; the issuer must publish a pre-issuance factsheet, yearly allocation reports and an impact report; and the external reviewer must be registered with and supervised by ESMA. Other green bonds may still be sold under the ICMA principles; the EuGB label signals a stricter, supervised standard. Check the current rules.

Worked example

Hypothetical example: a utility has two five-year bonds outstanding with the same seniority. Its conventional bond yields 3.50 %; its green bond yields 3.45 %. You consider investing EUR 10,000.

Greenium. 3.50 % − 3.45 % = 0.05 percentage points = 5 basis points.
Cost per year: EUR 10,000 × 0.0005 = EUR 5. Over five years: 5 × EUR 5 = EUR 25 of forgone interest (ignoring compounding, reinvestment, fees and taxes). You pay EUR 25 for the label, while your credit risk is unchanged.

Step-up on an SLB. The same utility offers a five-year SLB, 3.00 % coupon on EUR 1,000 nominal, with a 25 basis point step-up if its emissions target is missed at the end of year 2 (coupon 3.25 % for years 3–5).
Extra interest = EUR 1,000 × 0.0025 × 3 years = EUR 7.50 per bond, or 5 % of total coupons of 5 × EUR 30 = EUR 150. Small for the issuer; small compensation for you.

EuGB proportions. A EUR 500 million European green bond must allocate at least 0.85 × EUR 500 million = EUR 425 million to taxonomy-aligned activities; at most 0.15 × EUR 500 million = EUR 75 million may use the flexibility pocket.

Assumptions: yields and coupons are invented round numbers; no fees, spreads, accrued interest or taxes.

Common mistake

Practice activity

On paper: a seven-year SLB, EUR 1,000 nominal, coupon 4.00 %, steps up 25 basis points for years 5–7 if a KPI target is missed at the end of year 4. The issuer's conventional seven-year bond yields 4.10 %. (a) Greenium in basis points? (b) Maximum extra interest per bond if the target is missed? (c) Why might an investor still prefer a use-of-proceeds green bond?

Key takeaways

• Green, social and sustainability bonds ring-fence the proceeds; SLBs tie the coupon to a KPI. Neither changes the issuer's credit risk.
• Measure the greenium in euros on your position; it is usually small and in recent years has often been close to zero.
• Read an SLB's KPI, target, test date and step-up size before giving it credit for ambition.
• The EU Green Bond Standard (85 % taxonomy alignment, ESMA-supervised reviewers) is the strictest label as of 2026, but it is voluntary.

Next step

Lesson 10 turns to the other lever investors have besides buying and selling: stewardship, proxy voting and the evidence on engagement versus divestment.