IESET.
Hypotheses·fiscal·truss_2022_currency_user_ldi_collateral_mechanism

The September 2022 UK gilt-market dysfunction had its operative amplification mechanism in the foreign-currency-collateral exposure of the Liability-Driven Investment (LDI) leveraged-derivative chain in the UK pension system, not in a "fiscal limit" reached by the sovereign issuer.

Specifically, the 30y gilt yield spiked because forced LDI collateral calls on USD/EUR-denominated swap counterparties triggered a self-reinforcing fire-sale; UK pension funds were effectively foreign-currency users at the margin even though the UK sovereign was a currency issuer. The pattern was resolved by the BoE intervening as issuer-of-last-resort within four trading days, with full reversal of the gilt-yield spike, and the institutional reform that followed (LDI collateral standards) was a financial-stability measure rather than fiscal credibility restoration. This contrasts the MMT/PK currency-user-vs-issuer mechanism with the mainstream reading of Truss as a fiscal-credibility event.

INCONCLUSIVEengine/runs/truss_2022_currency_user_ldi_collateral_mechanism

INCONCLUSIVE_DATA_PENDING — no outcome variable loaded; missing: ['boe:IUDLG7N', 'boe:IUDMNZC', 'boe:gilt_volatility (manual); ice:UK_gilt_options', 'fred:DEXUSUK; boe:XUDLUSS', 'ecb:EXR.D.GBP.EUR; boe:XUDLERS', 'manual: BoE Financial Stability Report Dec 2022 + TPR LDI investigation tables']

confidence cueResult card produced; verdict unclassified.

policy briefCoverage too thin

In ordinary language

In plain terms, this asks whether mini budget announcement is actually linked to better or worse gilt yield 30y from 2022 to 2023.

plain answer

This test cannot make a firm call yet. no outcome variable loaded; missing: ['boe:IUDLG7N', 'boe:IUDMNZC', 'boe:gilt_volatility (manual); ice:UK_gilt_options', 'fred:DEXUSUK; boe:XUDLUSS', 'ecb:EXR.D.GBP.EUR; boe:XUDLERS', 'manual: BoE Financial Stability Report Dec 2022 + TPR LDI investigation tables']

why it matters

This matters because fiscal claims should change belief only when they survive a pre-declared empirical test.

how the test works

It compares 1 country or place units from 2022 to 2023, using a event study design, with fixed effects for date.

what was measured
What changed
  • Mini budget announcement
  • Boe gilt intervention announcement
What we checked
  • Gilt yield 30y
  • Gilt yield 10y
  • Gilt implied volatility
what this does not prove

A single test is not the whole truth. It narrows the claim under a specific sample, time period, and method. Strong policy conclusions need the pattern to survive nearby tests, alternative data, and serious objections.

verification

No evidence packet has been generated yet.

Results

engine/runs/truss_2022_currency_user_ldi_collateral_mechanism
1007550250202220232023GBR
illustrative sketch · run pending
No coefficients yet. When the model fires, this chart will show gilt_yield_30y across 1 sampled countries over 2022–2023.
The shapes above are stylised — none of the lines are real data.
Placeholder for truss_2022_currency_user_ldi_collateral_mechanism. Published chart will be generated from engine/runs/truss_2022_currency_user_ldi_collateral_mechanism/chart_data.json.

Pre-registration

pre-registered
first-spec commit 098ce96 · 2026-04-30T12:57:33Z
run generated · 2026-04-30T09:47:25Z

The September 2022 UK gilt-market dysfunction had its operative amplification mechanism in the foreign-currency-collateral exposure of the Liability-Driven Investment (LDI) leveraged-derivative chain in the UK pension system, not in a "fiscal limit" reached by the sovereign issuer. Specifically, the 30y gilt yield spiked because forced LDI collateral calls on USD/EUR-denominated swap counterparties triggered a self-reinforcing fire-sale; UK pension funds were effectively foreign-currency users at the margin even though the UK sovereign was a currency issuer. The pattern was resolved by the BoE intervening as issuer-of-last-resort within four trading days, with full reversal of the gilt-yield spike, and the institutional reform that followed (LDI collateral standards) was a financial-stability measure rather than fiscal credibility restoration. This contrasts the MMT/PK currency-user-vs-issuer mechanism with the mainstream reading of Truss as a fiscal-credibility event.

Falsification criterion — what would disprove this

set before the run · honoured after

This hypothesis is considered falsified if:

The hypothesis is falsified if any of the following hold for the September 2022 gilt-crisis window: (a) the 30y gilt yield does NOT fall by at least 100 basis points within 5 trading days of the BoE 28 September gilt-purchase facility announcement, (b) the BoE Financial Stability Report and TPR LDI investigation do NOT identify forced collateral calls on FX-denominated derivative positions as the proximate amplification mechanism, OR (c) GBP spot does NOT recover to within 3% of pre-mini-budget level by end-October 2022 absent further fiscal news. Falsification requires (a) AND ((b) OR (c)) — primary gate is the BoE intervention yield reversal.

formal test & threshold
test:      ldi_collateral_fire_sale_event_study_2022
threshold: 30y_gilt_yield reversal >= 100bp within 5 trading days of 2022-09-28 AND (BoE/TPR identifies LDI collateral channel OR GBP recovers to within 3% of pre-event level by 2022-10-31)

Method

Template
event_study
Fixed effects
date
Clustering
date
Sample
1 countries · 2022 – 2023
Evidence type
associational

High-frequency event study around the September 2022 gilt-crisis window. Primary identification: yield-reversal magnitude in 5 trading days post 28 September. Secondary: cross-walk against BoE FSR and TPR LDI commentary documenting forced-collateral-call mechanism. Robustness: GBP spot vs DXY-comparable basket to distinguish Truss-specific from global-rate channel.

Data

VariableSourceTransform
gilt_yield_30y
outcome
boe:IUDMNZCtier 1
bp_level
gilt_yield_10y
outcome
boe:IUDMNZCtier 1
bp_level
gilt_implied_volatility
outcome
manual:gilt_volatilitytier 4
ice:UK_gilt_optionstier 2
level
gbp_usd_spot
outcome
fred:DEXUSUKtier 1
boe:XUDLUSStier 1
log_level
gbp_eur_spot
outcome
ecb:EXR.D.GBP.EURtier 1
boe:XUDLERStier 1
log_level
ldi_collateral_call_volume
outcome
manual: BoE Financial Stability Report Dec 2022 + TPR LDI investigation tablesgbp_billion
mini_budget_announcement
treatment
constructed:indicator = 1 on 2022-09-23; 0 otherwisetier 5
event_dummy
boe_gilt_intervention_announcement
treatment
constructed:indicator = 1 on 2022-09-28 (BoE temporary gilt-purchase facility); 0 otherwisetier 5
event_dummy
boe_gilt_intervention_unwind
treatment
constructed:indicator = 1 on 2022-10-14 (extension end); 0 otherwisetier 5
event_dummy
truss_resignation
treatment
constructed:indicator = 1 on 2022-10-20; 0 otherwisetier 5
event_dummy
us_10y_yield
control
fred:DGS10tier 1
bp_level
bund_10y_yield
control
ecb:IRS.M.DEtier 1
fred:IRLTLT01DEM156Ntier 1
bp_level
vix
control
fred:VIXCLStier 1
level
boe_bank_rate
control
boe:IUDBEDRtier 1
level_pct

● ready  · ● pending  · ● reconstruct-needed

Detailed result card

Result card — truss_2022_currency_user_ldi_collateral_mechanism

Verdict: INCONCLUSIVE_DATA_PENDING — no outcome variable loaded; missing: ['boe:IUDLG7N', 'boe:IUDMNZC', 'boe:gilt_volatility (manual); ice:UK_gilt_options', 'fred:DEXUSUK; boe:XUDLUSS', 'ecb:EXR.D.GBP.EUR; boe:XUDLERS', 'manual: BoE Financial Stability Report Dec 2022 + TPR LDI investigation tables']

Pre-registration

  • Claim: The September 2022 UK gilt-market dysfunction had its operative amplification mechanism in the foreign-currency-collateral exposure of the Liability-Driven Investment (LDI) leveraged-derivative chain in the UK pension system, not in a "fiscal limit" reached by the sovereign issuer. Specifically, the 30y gilt yield spiked because forced LDI collateral calls on USD/EUR-denominated swap counterparties triggered a self-reinforcing fire-sale; UK pension funds were effectively foreign-currency users at the margin even though the UK sovereign was a currency issuer. The pattern was resolved by the BoE intervening as issuer-of-last-resort within four trading days, with full reversal of the gilt-yield spike, and the institutional reform that followed (LDI collateral standards) was a financial-stability measure rather than fiscal credibility restoration. This contrasts the MMT/PK currency-user-vs-issuer mechanism with the mainstream reading of Truss as a fiscal-credibility event.
  • Falsification rule: The hypothesis is falsified if any of the following hold for the September 2022 gilt-crisis window: (a) the 30y gilt yield does NOT fall by at least 100 basis points within 5 trading days of the BoE 28 September gilt-purchase facility announcement, (b) the BoE Financial Stability Report and TPR LDI investigation do NOT identify forced collateral calls on FX-denominated derivative positions as the proximate amplification mechanism, OR (c) GBP spot does NOT recover to within 3% of pre-mini-budget level by end-October 2022 absent further fiscal news. Falsification requires (a) AND ((b) OR (c)) — primary gate is the BoE intervention yield reversal.
  • Falsification test: ldi_collateral_fire_sale_event_study_2022
  • Event year: (not extracted)

Estimate

  • Error: no outcome variable loaded; missing: ['boe:IUDLG7N', 'boe:IUDMNZC', 'boe:gilt_volatility (manual); ice:UK_gilt_options', 'fred:DEXUSUK; boe:XUDLUSS', 'ecb:EXR.D.GBP.EUR; boe:XUDLERS', 'manual: BoE Financial Stability Report Dec 2022 + TPR LDI investigation tables']

Variables resolved

Variables missing data

  • boe:IUDLG7N (outcome, name=gilt_yield_30y)
  • boe:IUDMNZC (outcome, name=gilt_yield_10y)
  • boe:gilt_volatility (manual); ice:UK_gilt_options (outcome, name=gilt_implied_volatility)
  • fred:DEXUSUK; boe:XUDLUSS (outcome, name=gbp_usd_spot)
  • ecb:EXR.D.GBP.EUR; boe:XUDLERS (outcome, name=gbp_eur_spot)
  • manual: BoE Financial Stability Report Dec 2022 + TPR LDI investigation tables (outcome, name=ldi_collateral_call_volume)
  • constructed: indicator = 1 on 2022-09-23; 0 otherwise (treatment, name=mini_budget_announcement)
  • constructed: indicator = 1 on 2022-09-28 (BoE temporary gilt-purchase facility); 0 otherwise (treatment, name=boe_gilt_intervention_announcement)
  • constructed: indicator = 1 on 2022-10-14 (extension end); 0 otherwise (treatment, name=boe_gilt_intervention_unwind)
  • constructed: indicator = 1 on 2022-10-20; 0 otherwise (treatment, name=truss_resignation)
  • fred:DGS10 (controls, name=us_10y_yield)
  • ecb:IRS.M.DE; fred:IRLTLT01DEM156N (controls, name=bund_10y_yield)
  • fred:VIXCLS (controls, name=vix)
  • boe:IUDBEDR (controls, name=boe_bank_rate)

Generated by scripts/run_event_study.py at 2026-04-30T09:47:25+00:00

Strongest opposing argument

Every hypothesis ships with its charitable opposing argument. The framework earns credibility by handling objections at their strongest, not weakest.

Notes

Companion to the existing uk_truss_mini_budget_currency_sovereign_mechanism spec; that spec frames the question generally as institutional-rupture vs hard-fiscal-limit, while this candidate spec is more specific: the operative channel was the LDI collateral fire-sale, and the pension funds were the marginal currency-user. Tests the BIS / BoE Financial Stability Report decomposition. The standard mainstream read locates the mechanism in fiscal-credibility loss; this read locates it in institutional design and FX-collateral exposure of pension intermediaries.

Authored framework. Read the transparency note.