An interactive explainer of how Irish banks use SRT securitisations to manage capital, with worked examples and live calculations.
SRT is a regulatory mechanism that allows banks to transfer the credit risk on a pool of loans to third-party investors, thereby reducing the risk-weighted assets (RWAs) that drive capital requirements — without removing the loans from the balance sheet.
Banks must hold regulatory capital (CET1) against every loan. A large SME or mortgage book consumes significant capital that could otherwise support new lending or be returned to shareholders.
The bank creates a synthetic or true-sale securitisation. Protection sellers (investors) absorb losses on the portfolio up to an agreed level, in exchange for a fee (protection premium).
If the ECB/SSM confirms significant risk has genuinely transferred, the bank replaces the full RWA with a much smaller retained exposure, releasing CET1 capital.
Irish banks have predominantly used synthetic structures (credit-linked notes or CDS) rather than true-sale for their SRT transactions.
Loans remain on balance sheet. The bank buys credit protection (via CDS or CLN) on a reference portfolio from investors. Investors post collateral or issue notes to fund their exposure.
Loans are legally sold to an SPV which issues notes to market. The bank retains the senior tranche (low risk, low capital). More complex; derecognition accounting implications.
| Framework | Provision | Key Requirement |
|---|---|---|
| CRR II / CRR III | Art. 243–244 | Defines SRT tests for synthetic securitisation; significant transfer ≡ ≥50% of weighted risk on mezzanine tranches transferred |
| EBA Guidelines | EBA/GL/2023/01 | Supervisory convergence on SRT assessment; requirements on structural features, clean-up calls, excess spread |
| ECB SSM | Supervisory approval | Banks in SSM must obtain prior ECB permission before recognising capital relief; notification 6–8 weeks prior to execution |
| Securitisation Regulation | EU 2017/2402 | STS criteria (for traditional); risk retention (5% minimum by originator) |
| Basel III / CRR III | SEC-SA, SEC-IRBA | Method for calculating RWA on retained tranches post-SRT |
A typical Irish bank synthetic SRT involves five parties and three tranches. Here is how the cashflows and risk transfer work in practice.
Losses on the reference portfolio flow through the capital structure from the bottom up. The bank retains the senior tranche (and the first-loss piece for regulatory reasons) but transfers the mezzanine risk to investors.
The bank selects a static or revolving pool (e.g., €2bn Irish SME loans). Eligibility criteria exclude NPLs, concentrations over limits, and loans nearing maturity. The pool is fixed or managed within agreed parameters.
The bank defines attachment/detachment points (e.g., 0–5% junior, 5–15% mezzanine, 15–100% senior). These are calibrated against historical loss data and ECB stress tests. The mezzanine tranche must be large enough to evidence significant risk transfer.
The bank pays a quarterly premium (e.g., EURIBOR + 600–900 bps) to the protection seller for the mezzanine tranche. This is priced off the expected loss, capital relief benefit, and market comparables.
If a reference loan defaults, losses are first absorbed by the junior tranche (bank). Once the junior is exhausted, the mezzanine investor bears losses up to their detachment point. A credit event notice is served; the protection seller pays the settlement amount.
Post-ECB approval, the bank replaces the blended IRB treatment with: (i) a full CET1 deduction on the first-loss tranche (capped at its face value) + (ii) a low SEC-IRBA risk weight on the retained senior tranche + (iii) zero capital on the mezzanine (transferred). The junior tranche becomes more expensive in isolation, but the senior saving dominates and net capital release is material.
Illustrative transaction: Bank of Erin executes a synthetic SRT on a €2 billion Irish SME loan portfolio. Follow the numbers step by step.
| Item | Amount | Notes |
|---|---|---|
| Reference portfolio (EAD) | €2,000m | Irish SME corporate loans, performing |
| Average IRB risk weight | 85% | Calibrated to historical PD/LGD; typical for Irish SME |
| RWA (pre-SRT) | €1,700m | = €2,000m × 85% |
| CET1 required (13.5%) | €229.5m | Capital the bank must hold against this book |
| Tranche | Attachment | Detachment | Size (€m) | Held By |
|---|---|---|---|---|
| Junior (First Loss) | 0% | 5% | €100m | Bank (retained) |
| Mezzanine | 5% | 15% | €200m | Investors (TRANSFERRED) |
| Senior | 15% | 100% | €1,700m | Bank (retained) |
| Total Portfolio | — | — | €2,000m |
Protection premium paid to investors: EURIBOR 3M + 750 bps per annum on the €200m mezzanine notional = ~€15m p.a. at current rates.
| Retained Piece | Exposure | Capital Required | Capital Treatment |
|---|---|---|---|
| Junior tranche (0–5%) | €100m | €100m | 1,250% RW → €100m × 1,250% × 13.5% = €168.75m, capped at exposure value = €100m CET1 deduction. |
| Mezzanine (transferred) | €200m | €0m | Risk fully transferred to investors — zero capital for bank |
| Senior tranche (15–100%) | €1,700m | €27.5m | SEC-IRBA: ~12% RW → €1,700m × 12% × 13.5% |
| Total post-SRT | €2,000m | €127.5m |
| Tranche | Pre-SRT capital | Post-SRT capital | Change |
|---|---|---|---|
| Junior €100m (0–5%) | €100m × 85% × 13.5% = €11.5m | €100m deduction = €100m | +€88.5m ▲ cost |
| Mezzanine €200m (5–15%) | €200m × 85% × 13.5% = €23m | Transferred → €0 | −€23m ▼ saving |
| Senior €1,700m (15–100%) | €1,700m × 85% × 13.5% = €195m | €1,700m × 12% × 13.5% = €27.5m | −€167.5m ▼ saving |
| Total | €229.5m | €127.5m | −€102m net relief |
All three tranches treated at blended 85% IRB RW × 13.5%
Junior deducted (€100m) + senior at 12% RW (€27.5m) + mezzanine zero
The senior saving (€167.5m) does the heavy lifting. The junior tranche cost increases sharply (+€88.5m) — this is the real capital cost of skin-in-the-game. Banks therefore want the junior tranche as thin as the ECB will accept.
Under CRR Art. 244, significant risk transfer in synthetic securitisation is assessed by two alternative tests:
The mezzanine RWA transferred must exceed 50% of the total mezzanine + junior RWA. In our example: €200m mezzanine at (say) 200% avg RW = €400m RWA transferred. Mezzanine + junior RWA = €400m + €1,250m = €1,650m. 400/1,650 = 24% — may not pass this test alone.
The ECB/SSM may confirm SRT based on a holistic assessment even if Test A fails. The supervisor evaluates structural features, the adequacy of the mezzanine size relative to expected losses, and absence of implicit support provisions. Most Irish bank SRTs rely on Test B.
Adjust the parameters below to see how SRT capital relief changes under different structuring assumptions.
For Irish banks (AIB, Bank of Ireland, PTSB) supervised directly by the ECB under the SSM, prior supervisory approval is mandatory before capital relief can be recognised. This is a rigorous multi-stage assessment.
Bank engages informally with its Joint Supervisory Team (JST). Early sharing of transaction term sheet, draft legal documentation, portfolio data tape, and proposed tranche structure. The ECB will flag structural concerns early to avoid late-stage issues.
Formal submission includes: complete legal docs, portfolio stratification, tranching rationale, internal capital model outputs, stress test scenarios, excess spread analysis, and a self-assessment against the EBA SRT Guidelines. The ECB has 15 business days to respond but in practice takes 6–8 weeks.
The ECB runs its own quantitative models to verify the risk transfer is genuine. Key checks: (a) is the mezzanine sized relative to expected loss? (b) does excess spread embedded in the structure effectively nullify the protection? (c) are the protection premiums market-consistent or below market (raising subsidy concerns)?
The ECB evaluates: (a) no implicit support clauses; (b) clean-up call limited to 10% of original pool; (c) bank cannot repurchase transferred assets at above-market prices; (d) no substitution rights that allow the bank to cherry-pick portfolios post-execution.
If satisfied, the ECB issues a formal non-objection. Capital relief is then recognised from the settlement date. The bank must notify the ECB annually during the transaction's life if any structural changes occur. Ongoing monitoring is conducted by the JST.
Portfolio yield: 6.5% | Funding cost: 2.5% | Excess spread: 4% p.a. × 5yr = 20% cumulative. If the mezzanine is only 10% of the pool, the excess spread effectively covers the mezzanine — so investors bear no real economic risk. SRT likely denied or scaled back.
Bank structures the deal so excess spread is released to the originator periodically rather than trapped. Or the mezzanine is sized significantly above cumulative projected excess spread. ECB satisfied that investors face genuine losses beyond expected levels.
Consider a €2,000m portfolio with a 10% mezzanine tranche (€200m) and 20% cumulative excess spread trapped in the structure. Assume a severe stress scenario of 12% cumulative losses over 5 years.
Loss waterfall with 20% spread buffer sitting ahead of the tranches:
Even under severe stress the investors paid nothing. The bank's own income stream bore all the risk — not the investors. ECB rejects the SRT.
Loss waterfall when spread flows out to the bank each quarter:
Investors bore genuine, substantial losses. Risk transfer is real. ECB approves the SRT.
| Issue | Description | Fix |
|---|---|---|
| Insufficient mezzanine | Mezzanine too thin relative to stressed losses; investors not bearing meaningful risk | Increase mezzanine thickness; use conservative loss scenario in sizing |
| Excess spread trap | Spread absorbed before mezzanine investors take losses | Release excess spread to originator on each payment date |
| Implicit support features | Bank has option to substitute non-performing assets or provide liquidity facilities | Remove all implicit support; strict substitution criteria |
| Below-market premium | Protection premium below what an arm's-length investor would require; suggests subsidy | Benchmark premium to comparable CDS market; obtain third-party pricing opinion |
| Clean-up call >10% | Call option allows bank to collapse structure at >10% of original pool — ECB views as implicit support | Limit clean-up call to ≤10% per CRR requirement |
AIB, Bank of Ireland, and Permanent TSB have all engaged in SRT activity. Their motivations, portfolio types, and capital strategies shape how and why they pursue these transactions.
AIB has executed SRT transactions on its SME and corporate lending books. Given its strong organic capital generation (~200 bps p.a.), SRT has been used opportunistically to fund buybacks and maintain headroom above targets rather than as a capital emergency tool.
BOI has used SRT across multiple asset classes, including UK commercial real estate and Irish corporate loans. Their UK operations create additional cross-border structuring considerations under both PRA and ECB supervisory frameworks.
PTSB's balance sheet is predominantly residential mortgages. SRT is less common for standard RMBS (which have lower RWs under IRB), but PTSB has explored portfolio SRT for its tracker mortgage book and BTL exposures where capital drag is more acute.
| Asset Class | Typical IRB RW | SA RW | Floor (72.5% × SA) | SRT Still Useful? |
|---|---|---|---|---|
| Irish Residential Mortgages (LTV<80%) | 10–20% | 35% | 25.4% | Reduced benefit |
| Buy-to-Let Mortgages | 25–45% | 75% | 54.4% | Moderate |
| Irish SME Corporate | 70–100% | 85–100% | 62–72% | Strong — floor less binding |
| Comm. Real Estate | 80–150% | 100% | 72.5% | Strong for higher RW exposures |
Four practical questions about how SRT transactions work in practice: how the premium functions, why the bank is protected even if the investor defaults, what is publicly disclosed about pricing, and how transaction terms are structured.
The economics of an SRT premium are straightforwardly insurance-like. The bank continues to collect all interest and principal from the underlying loans exactly as before — customer relationships are undisturbed, nothing changes operationally, and all loan cashflows keep flowing to the bank. The only outflow is the protection premium paid to the investor.
In the CLN structure used by Irish banks, the bank is fully protected regardless of what happens to the investor. This is the key structural advantage of funded over unfunded protection.
When the CLN is issued, the investor pays €200m cash to the SPV. This money leaves the investor's hands immediately on day one — it is not a future promise to pay.
The SPV invests the €200m in high-quality collateral — typically AAA-rated sovereign bonds. This collateral is legally isolated from the investor in the SPV's own ringfenced estate. If the investor goes insolvent the next day, the collateral is unaffected.
Under the transaction documents, the bank has a senior secured claim on the SPV's collateral. If losses hit the mezzanine, the SPV liquidates the required amount of collateral and pays the bank — no dependence on the investor's solvency at all.
If the transaction runs to maturity with no losses on the mezzanine, the collateral (now slightly grown from coupon income on the bonds) is returned to the investor along with the premium income earned over the life of the deal.
In an unfunded structure the investor simply promises to pay losses if they occur. The bank retains counterparty credit risk — if the investor defaults before paying a claim, the bank is exposed. Additional capital must be held against this risk unless the protection seller is highly rated. ECB scrutinises these carefully.
The investor's obligation is pre-funded and ringfenced from day one. The bank's only residual risks are collateral market risk (mitigated by AAA eligibility criteria) and legal/structural risk (mitigated by extensive documentation and legal opinions). ECB strongly prefers this structure.
Irish banks disclose that SRT transactions exist and the capital benefit they generate, but precise premium rates are treated as commercially sensitive and are not published.
| Source | What Is Disclosed | What Is Not Disclosed |
|---|---|---|
| Annual Report / Pillar 3 | SRT transactions referenced in capital management section; RWA relief in basis points of CET1; sometimes notional portfolio size | Premium rate; spread over EURIBOR; all-in cost; investor identity |
| Results Presentations | CET1 impact in bps (allows rough back-calculation of notional); capital strategy rationale | Pricing; deal economics; maturity |
| Prospectus (if public CLN) | Full structural detail including indicative pricing, attachment points, portfolio stratification | Most Irish bank SRTs are privately placed — no prospectus required |
| Market Convention | Mezzanine SRT pricing for European bank SME/corporate books: broadly EURIBOR + 600–900 bps depending on portfolio quality and tranche thickness | Bank-specific rates; this is market colour not disclosed data |
Broadly matched to the weighted average life of the reference portfolio. A 5-year SME loan book would typically underpin a 4–6 year SRT. Mismatching term and portfolio life creates basis risk and ECB concern about the economic rationale.
For static reference portfolios, the notional reduces as loans repay. The premium income to the investor falls in line. The transaction self-liquidates over time, which is administratively clean but means the capital relief also diminishes as the pool shrinks.
New eligible loans are substituted in as old ones repay, keeping the notional constant for the revolving period (typically 2–3 years) before entering an amortisation phase. Maintains full capital relief for longer but requires strict substitution criteria to prevent adverse selection.
| Feature | Mechanism | Regulatory Constraint |
|---|---|---|
| Scheduled maturity | Expected end date; drives premium pricing and investor commitment period | Must reflect WAL of portfolio; ECB sceptical of mismatched terms |
| Legal maturity | Longer than scheduled; allows time for loss settlements and credit event resolution after scheduled end | Gap typically 6–12 months beyond scheduled maturity |
| Clean-up call | Bank's option to terminate early once portfolio amortises to ≤10% of original notional — avoids administering a tiny residual structure | CRR hard cap at 10%; above this threshold the ECB treats it as implicit support, undermining the SRT |
| Extension | Both parties may agree to extend if portfolio is performing and investor appetite remains; premium is reset to prevailing market rates | Any extension requires fresh ECB notification; capital relief continues only with ongoing supervisory comfort |
| Premium sensitivity | Longer term = higher spread demanded by investors for duration and uncertainty; rate-sensitive given floating EURIBOR component | Premium must remain market-consistent throughout; below-market pricing triggers ECB implicit support concerns |