In This Article
On the evening of Sunday, March 19, 2023, officials from the Swiss Federal Department of Finance, the Swiss National Bank (SNB), and the Swiss Financial Market Supervisory Authority (FINMA) announced the state-brokered rescue of Credit Suisse by its arch-rival, UBS Group AG [2][3]. Under the emergency transaction, Credit Suisse shareholders received CHF 3 billion (approximately US$3.2 billion) in UBS stock [3][4]. Simultaneously, however, FINMA ordered Credit Suisse to write down the entire principal value of its 13 outstanding Additional Tier 1 (AT1) hybrid bond issues—carrying a nominal value of roughly CHF 16 billion to CHF 16.5 billion (about US$17 billion)—to zero [2][3][4].
The decision stunned global fixed-income markets. In a conventional corporate bankruptcy or bank resolution, common equity occupies the bottom of the capital structure and must be completely extinguished before any class of bondholders suffers a principal loss [4][5]. By wiping out US$17 billion of perpetual subordinated debt while preserving CHF 3 billion in value for common shareholders, the Swiss intervention inverted traditional creditor hierarchy expectations [1][3][4]. Within twenty-four hours, central banks and resolution authorities across the European Union and the United Kingdom issued formal declarations distancing their statutory regimes from the Swiss precedent—and within two and a half years, thousands of bondholder lawsuits culminated in a landmark October 2025 ruling by the Swiss Federal Administrative Court revoking FINMA’s write-off decree as unlawful [2][4][5].
Post-2008 Basel III Architecture and the Design of AT1 Capital
Additional Tier 1 bonds—often called contingent convertible bonds, or “CoCos”—were created after the 2007–2009 global financial crisis as a cornerstone of the Basel III international capital adequacy framework [6]. Determined to prevent taxpayer-funded bank bailouts, the Basel Committee on Banking Supervision required banks to hold higher buffers of loss-absorbing capital relative to their risk-weighted assets: Common Equity Tier 1 (CET1) had to exceed 4.5 percent of risk-weighted assets, total Tier 1 capital (comprising CET1 plus AT1 instruments) had to exceed 6 percent, and combined Tier 1 and Tier 2 capital had to exceed 8 percent, before adding conservation and systemic surcharges [6].
Unlike Tier 2 subordinated debt, which absorbs losses only after a bank enters formal insolvency or liquidation (“gone-concern” capital), AT1 bonds were engineered as “going-concern” capital designed to absorb losses while a distressed bank remains open and operating [3][6]. Issued as perpetual securities with no maturity date, AT1 bonds allow the issuing bank to cancel coupon (interest) payments at its discretion without triggering an event of default [6].
More importantly, every AT1 bond contract contains automatic loss-absorption triggers [3]. Under European Union banking rules (the Capital Requirements Regulation), standard AT1 contracts are anchored to a quantitative accounting trigger—typically when a bank’s CET1 ratio falls below 5.125 percent or 7 percent of risk-weighted assets [3]. Once that trigger is breached, or if regulators determine that the bank has reached a statutory Point of Non-Viability (PoNV), the bond’s principal is either converted into common equity shares or written down temporarily or permanently [3][6]. Because of this embedded risk of total loss, AT1 bonds offered significantly higher yields than senior bank debt, attracting institutional asset managers and private wealth investors worldwide [1][6].
| Documented Figure / Metric | Historical Significance & Archival Context |
|---|---|
| ₹8,415 crore | As part of that salvage operation on March 14, 2020, the administrator wrote down ₹8,415 crore (roughly US$1.1 billion) of Yes Bank's AT1 bonds in full while existing common shareholders retained their locked-in equity stakes. |
| CHF 50 billion | An initial emergency liquidity line of CHF 50 billion from the Swiss National Bank failed to stem the flight, as daily deposit withdrawals exceeded CHF 10 billion later that week. |
| 94 banks | 1356, examining bond-level data from 94 banks across 22 countries) demonstrated how powerfully markets responded to this divergence. |
Early Precedents: India’s Yes Bank Write-Down and Contractual Nuances
Long before the March 2023 crisis in Zurich and Bern, an emerging-market banking rescue in India illustrated both the power of Basel III AT1 write-down clauses and the fierce judicial battles they could provoke [6][7]. In March 2020, following severe governance failures and loan losses at Yes Bank, the Reserve Bank of India (RBI) superseded the lender’s board, appointed an administrator, and implemented a state-backed reconstruction scheme led by the State Bank of India [6][7]. As part of that salvage operation on March 14, 2020, the administrator wrote down ₹8,415 crore (roughly US$1.1 billion) of Yes Bank’s AT1 bonds in full while existing common shareholders retained their locked-in equity stakes [6][7].
Wiped-out Indian bondholders challenged the decision in court, arguing that the reconstruction scheme notified by the government had not authorized extinguishing AT1 debt ahead of equity [7]. On January 20, 2023—just two months before Credit Suisse’s collapse—the Bombay High Court quashed the Yes Bank write-down, a ruling later upheld by the Supreme Court of India in October 2026 [7].
In Switzerland, meanwhile, the AT1 contracts issued by Credit Suisse and UBS differed in two critical ways from standard European bank hybrids [3]. First, rather than converting into common stock when triggered, Credit Suisse’s 13 AT1 bond series were structured strictly as “write-off bonds” with a conditional debt waiver: if a trigger event occurred, their principal was permanently written down to zero without granting bondholders a single share of equity [2][3]. Second, alongside a standard quantitative CET1 ratio trigger, Credit Suisse’s prospectuses included qualitative “Viability Event” clauses [2][3]. Under the third trigger clause documented by the Single Resolution Board, a permanent write-down could be activated if the Swiss regulator determined that customary measures to restore capital were infeasible and that public-sector support was required to prevent insolvency or illiquidity [3].
March 2023: The Run on Credit Suisse and the CHF 16.5 Billion Wipeout
Years of risk-management scandals—including multibillion-dollar losses from the collapses of Archegos Capital Management and Greensill Capital in 2021—had already eroded market confidence in Credit Suisse when the failure of Silicon Valley Bank on March 10, 2023, ignited a global banking panic [1][3][4]. During the third week of March 2023, Credit Suisse suffered a catastrophic run on its demand and time deposits [1][3]. An initial emergency liquidity line of CHF 50 billion from the Swiss National Bank failed to stem the flight, as daily deposit withdrawals exceeded CHF 10 billion later that week [1][3].
Although Swiss regulators had spent more than a decade preparing a formal “too-big-to-fail” resolution plan that envisioned bailing in senior and subordinated debt at the holding-company level, the Swiss Federal Council, the SNB, and FINMA concluded over the weekend of March 18–19, 2023, that putting a global systemically important bank into statutory resolution amid fragile market conditions posed unacceptable contagion risks [1][3]. Instead, authorities invoked emergency constitutional powers to orchestrate an immediate merger with UBS [2][3].
Under the rescue package announced on March 19, 2023:
- UBS agreed to acquire Credit Suisse in an all-stock transaction valuing Credit Suisse’s common equity at CHF 3 billion (roughly US$3.2 billion) [3][4].
- The Swiss National Bank provided emergency liquidity assistance lines—including a CHF 100 billion Public Liquidity Backstop carrying a federal default guarantee—offering up to CHF 200 billion jointly in public funding access [3].
- The Swiss Confederation granted UBS a loss-protection guarantee of up to CHF 9 billion to cover potential losses on a designated portfolio of Credit Suisse non-core assets (after UBS absorbed the first CHF 5 billion of losses) [3].
- On the same day, the Swiss Federal Council amended its Emergency Ordinance by inserting Article 5a, authorizing FINMA to order the write-off of Tier 1 core capital [2][3]. Relying on Article 5a and the third contractual “Viability Event” trigger in the bond prospectuses, FINMA issued a decree on March 19, 2023, instructing Credit Suisse to permanently write down all CHF 16.5 billion (approximately US$17 billion) of its AT1 bonds to zero [2][3].
Global Market Repricing and European Regulatory Pushback
When Asian and European markets opened on Monday, March 20, 2023, prices of AT1 bonds issued by European and British banks plunged as investors feared that other regulators might similarly wipe out AT1 debt ahead of common equity [1][4]. Recognizing the threat to a crucial funding market for bank capital, foreign authorities intervened immediately to reaffirm the absolute priority of claims in their jurisdictions [1][4][5].
On the morning of March 20, 2023, European Central Bank (ECB) Banking Supervision, the Single Resolution Board (SRB), and the European Banking Authority (EBA) issued a joint statement declaring that under the European Union resolution framework, “common equity instruments are the first ones to absorb losses, and only after their full use would Additional Tier 1 be required to be written down” [4]. Hours later, the Bank of England published its own statement on the UK creditor hierarchy, noting that in its resolution of Silicon Valley Bank UK the previous week, all AT1 and Tier 2 instruments had been written down alongside the transfer of common equity for £1, and confirming that AT1 instruments strictly rank ahead of CET1 and behind Tier 2 in the British statutory order [5]. Similar clarifications followed from the Bank of Canada and the Hong Kong Monetary Authority [3].
Empirical research published by the Bank for International Settlements (BIS Working Paper No. 1356, examining bond-level data from 94 banks across 22 countries) demonstrated how powerfully markets responded to this divergence [1]. Yield spreads on AT1 bonds rose sharply and remained elevated in Switzerland, reflecting heightened regulatory and contractual risk premia, whereas AT1 spreads fell back across the euro area and the United Kingdom following the March 20 regulatory assurances [1]. Paradoxically, spreads on senior “bail-in” bonds narrowed across all jurisdictions—especially for weaker banks—as investors concluded from the Credit Suisse rescue that authorities were reluctant to impose losses on senior bail-in creditors during a systemic crisis [1].
Termination of State Guarantees and the October 2025 Court Reversal
For UBS and the Swiss treasury, the operational stabilization of Credit Suisse proceeded rapidly. UBS formally completed the legal acquisition of Credit Suisse on June 12, 2023, and on August 11, 2023, UBS voluntarily terminated both the CHF 9 billion federal loss-protection guarantee and the CHF 100 billion SNB public liquidity backstop, ending direct taxpayer exposure [3].
For the wiped-out AT1 bondholders, however, the battle moved to the courts. Roughly 3,000 complainants filed appeals across approximately 360 separate cases before the Swiss Federal Administrative Court in St. Gallen, arguing that neither the contractual terms of the AT1 prospectuses nor Swiss banking statutes permitted expropriating bondholders when Credit Suisse still met its regulatory capital ratios and shareholders were receiving CHF 3 billion [2][6].
On October 1, 2025 (published mid-October 2025), the Swiss Federal Administrative Court issued a landmark partial judgment in lead case B-2334/2023, revoking FINMA’s March 19, 2023 write-off decree as unlawful [2][6]. The court ruled on two independent grounds. First, it held that the contractual “Viability Event” in the bond prospectuses had never been triggered: at the moment of the write-off on March 19, 2023, Credit Suisse remained sufficiently capitalized, and the government-backed SNB facilities were liquidity measures that did not directly bolster equity capital [2][6]. Second, the court found that no valid statutory basis existed for overriding bondholders’ property rights: Article 26 of the Banking Act and Article 31 of the Financial Market Supervision Act were too vague to authorize expropriating third-party creditor claims, and Article 5a of the Federal Council’s Emergency Ordinance violated the Swiss Federal Constitution’s limits on emergency decrees, delegation of expropriation powers, and the constitutional guarantee of property ownership [2]. While FINMA and UBS announced appeals to the Swiss Federal Supreme Court, the ruling underscored the central lesson of the Credit Suisse AT1 episode: emergency financial stabilization cannot durably override the rule of law and contractual creditor hierarchies [1][2][6].
Theoretical & Balance-Sheet Transmission Mechanism
In the Kindleberger–Minsky taxonomy of financial instability (Kindleberger, 1978; Minsky, 1986) and Irving Fisher’s (1933) debt-deflation framework, speculative asset booms become systemic crises when credit expansion shifts balance sheets from hedge finance (cash flows covering principal and interest) to speculative and Ponzi finance (relying on rising asset prices and short-term margin roll-overs).
Once monetary tightening or an exogenous shock halts price appreciation, forced margin liquidations trigger Fisherian debt-deflation: fire-sale asset discounts erode bank collateral values, contracting credit supply across the real economy.
Sources and Further Reading
- Alessandro Di Stefano, Yvan Lengwiler, and Kumar Rishabh, “ The credibility of bail-in,” Bank for International Settlements (BIS Working Papers No. 1356), June 2026. Central Bank / Monetary Authority
- Swiss Federal Administrative Court, “ Unlawful write-off of AT1 capital instruments (Press release regarding judgment B-2334/2023),” Swiss Federal Administrative Court (BVGer), October 2025. Historical & Financial Reference
- Single Resolution Board, “ The 2023 Banking Turmoil: Some preliminary take-aways for resolution,” Single Resolution Board (SRB), September 2023. International Financial Institution
- Single Resolution Board, “ EU regulators distance themselves from Credit Suisse bond writedowns,” Single Resolution Board (SRB), March 2023. International Financial Institution
- Bank of England, “ Bank of England Statement: UK creditor hierarchy,” Bank of England, March 20, 2023. Central Bank / Monetary Authority
- IMPRI Impact and Policy Research Institute, “ Reconsidering The Impact: Why The Swiss Court’s AT1 Ruling Has Limited Relevance For The YES Bank Case,” IMPRI Impact and Policy Research Institute, October 2025. Historical & Financial Reference
- The Hindu, “ Yes Bank weighs legal option after SC ruling, stares at 250 bps CET1 impact,” The Hindu, October 16, 2026. Historical & Financial Reference
- Irving Fisher — "The Debt-Deflation Theory of Great Depressions," Econometrica 1, no. 4 (FRASER Federal Reserve Archive, 1933): 337–357 Central Bank / Monetary Authority
- Charles P. Kindleberger & Robert Z. Aliber — Manias, Panics, and Crashes: A History of Financial Crises (Palgrave Macmillan) Peer-Reviewed / Academic Research
Cite This Historical Dossier (APA / Chicago)
APA (7th ed.): Ç., S. (Ed.). (2026). Credit Suisse and the CHF 16.5 Billion AT1 Bond Write-Down. In Forgotten Fortunes Historical Monograph Series (Forgotten Fortunes Editorial Desk). https://forgottenfortunes.net/credit-suisse-at1-bonds-credit-suisse-at1-bond-write-down/
MLA (9th ed.): Ç., Soner, ed. "Credit Suisse and the CHF 16.5 Billion AT1 Bond Write-Down." Forgotten Fortunes: Financial & Monetary History Archive, 2026, https://forgottenfortunes.net/credit-suisse-at1-bonds-credit-suisse-at1-bond-write-down/.
Chicago (17th ed.): Ç., Soner, ed. "Credit Suisse and the CHF 16.5 Billion AT1 Bond Write-Down." Forgotten Fortunes Historical Monograph Series (Forgotten Fortunes Editorial Desk), August 28, 2026. https://forgottenfortunes.net/credit-suisse-at1-bonds-credit-suisse-at1-bond-write-down/.
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