What Happened
On September 23, 2022, Chancellor Kwasi Kwarteng announced the largest tax cuts in 50 years — £45 billion unfunded. The plan was supply-side economics: cut taxes, stimulate growth, and the revenue would follow. Markets did not believe it.
In 4 days, UK 30-year gilt yields rose 130bps. The pound fell to near parity with the dollar. UK defined benefit pension funds, which had used liability-driven investment (LDI) strategies leveraged on gilts, faced margin calls they could not meet. The Bank of England intervened with emergency gilt purchases on September 28 to prevent a pension fund collapse that would have been systemically catastrophic.
Kwarteng was fired on October 14, 17 days after his budget. His replacement Jeremy Hunt reversed virtually every measure within hours. Truss resigned on October 20 — 45 days in office. The episode was the clearest demonstration in a generation that bond markets impose fiscal discipline when governments will not impose it on themselves.
The Mechanism
Fiscal credibility and the bond market vetoGovernments borrow money from bond markets continuously. Bond investors price fiscal risk. When a government announces policies that are not credibly funded — large unfunded tax cuts without corresponding spending reductions or credible growth assumptions — bond investors demand a higher yield to compensate for the increased risk. Higher yields immediately increase the government's borrowing costs, worsening the fiscal position they were trying to improve. The LDI pension crisis added a systemic dimension: the yield spike triggered margin calls that required gilt selling, which pushed yields higher still.
What the Consensus Believed
The prevailing view before the reckoning
Supply-side tax cuts would stimulate growth sufficient to fund themselves. The political commitment of a newly elected government with a large parliamentary majority would provide credibility. The UK had never experienced a bond vigilante crisis of this magnitude.
What the Record Shows
Fiscal credibility is binary
Markets either believe a government's fiscal plan or they do not. There is no middle ground. Once credibility is lost, it is extremely difficult to restore without policy reversal.
LDI leverage amplified the crisis
The pension fund LDI strategies created a feedback loop: yield rise triggered margin calls, which required gilt selling, which raised yields further. Financial engineering created systemic risk that nobody had mapped.
The template for bond vigilantism
The Truss episode became the reference case for what happens when fiscal policy ignores market constraints. Every finance minister in every country studied it.
45 days is the timeline
From announcement to resignation was 28 days. Bond markets can end a government faster than any political process.
↑ Cognitive pattern: Authority Bias — Believing political will substitutes for economic logic
Key Voices
Called It Right
Paul Johnson
Institute for Fiscal Studies
“The UK government has lost control of its finances. The gilt market will impose discipline very quickly.”
September 23, 2022 Right within 4 days
Larry Summers
Harvard
“The UK is behaving like an emerging market. The policies are not credible and the market will say so.”
September 2022 Right
Various economists
Multiple institutions
“Liz Truss will not last 6 weeks as PM once the gilt crisis forces a reversal.”
September 30, 2022 Right — 45 days
Wrong
Kwasi Kwarteng
HM Treasury
“The growth plan is the right approach and we will not reverse course.”
October 3, 2022 Fired October 14
Liz Truss
Prime Minister
“I am a fighter not a quitter. We will deliver on our plan.”
October 12, 2022 Resigned October 20