The numbers themselves tell a compelling and sobering story. The fiscal 2025 deficit closed at $1.78 trillion, or 5.8% of GDP. Fiscal 2026 is running wider: the shortfall reached $1.8 trillion in the first ten months (October to July), and CBO's August 2026 estimate puts the full-year figure at $2.1 trillion, above 6% of GDP on CBO's August estimate and $200 billion above its February baseline, a level never before realised outside of wars and recessions. The primary deficit, which must be roughly in balance to stabilise the debt-to-GDP ratio, sits at approximately 3% of GDP. Gross public debt outstanding passed $40 trillion in August 2026, per Treasury's Debt to the Penny, having crossed $39 trillion only in March on the same measure.

The structural drivers are well understood but politically intractable. Mandatory spending programmes, primarily Social Security, Medicare, and Medicaid, account for the majority of federal outlays and are growing faster than revenue. Net interest on the debt exceeded $1 trillion in fiscal 2025 and is running 14% higher in fiscal 2026; through July it totalled $931 billion against $804 billion for national defence. This creates a self-reinforcing cycle: higher rates increase debt service costs, which widen the deficit, which requires more borrowing, which puts further upward pressure on rates.

The "One Big Beautiful Bill Act" (OBBBA), signed in July 2025, has added significant fiscal impulse. CBO estimates, as reported in the press, put the legislation's addition to federal deficits over the next decade in the trillions of dollars, through permanent extension of the 2017 tax cuts, expanded SALT deductions, and full expensing provisions. The revenue side has since weakened further: the Supreme Court's February 2026 ruling that IEEPA does not authorise tariffs halted collections and triggered refunds, and CBO now expects fiscal 2026 customs receipts to come in about $250 billion below its earlier projection. All of this is occurring during a period of relative economic stability, not in response to a crisis, making it a historical outlier comparable only to wartime or pandemic-era fiscal expansions.

The bond market is the primary transmission mechanism. In a fiscal dominance regime, the supply of government debt grows persistently faster than the market's natural demand for it. This puts structural upward pressure on yields, particularly at the long end, as investors require higher term premiums to absorb increasing issuance. The February edition of this report anticipated a drift toward 4.5% on the 10-year by year-end 2026; the market moved through that level by the summer. The 10-year closed at 4.79% and the 30-year at 5.27% on 1 September 2026, after both touched roughly 20-year highs in mid-August. The Treasury's response, announced on 19 August, was to at least double its buybacks of 10- to 30-year debt to $4 billion per operation from 9 September; the relief in yields lasted days. Foreign demand is softening at the margin: official data show foreign holdings of Treasuries fell to $9.3 trillion in June 2026, with China's holdings at their lowest since 2008. The framework suggests the long end remains exposed to further term premium expansion, with 5% on the 10-year no longer a tail scenario.

A structural shift is underway in how investors assess sovereign versus corporate credit. Corporate fiscal discipline has driven the fastest pace of credit upgrades in a decade, while G-7 governments show little restraint. High-quality corporate bonds are increasingly viewed by institutional investors as safer than sovereign debt on a relative basis, a development with significant implications for portfolio construction and asset allocation.

For equities, the relationship with fiscal policy is complex and non-linear. In the near term, fiscal expansion is supportive. The OBBBA provides direct tailwinds through full expensing, expanded deductions, and lower effective tax rates. The S&P 500 returned 17.9% including dividends in 2025 and has added roughly 12% in price terms in 2026 through early September, even as long-dated yields have risen. But the bond market's response, a "bear steepener" driven by deficit expectations and now visible in a 30-year yield above 5.2%, signals that the long-term cost is being priced in real time.

The fiscal dominance dynamic is playing out across advanced economies simultaneously. France's public deficit came in at 5.1% of GDP in 2025, and the European Commission's Spring 2026 forecast sees it unchanged at 5.1% in 2026 before widening to 5.7% in 2027, with gross debt approaching 118% of GDP; persistent political instability since the 2024 snap elections has made meaningful consolidation exceptionally difficult. French 10-year government bond yields converged with Italy's around the turn of the year, a development that would have been considered extraordinary just two years ago.

Germany, long the anchor of European fiscal discipline, has shifted course. The announcement of a 500 billion euro infrastructure fund represents a historic departure from the fiscal conservatism that defined German economic policy for decades. While the economic rationale is sound, the signal to markets is clear: even the most disciplined advanced economies are moving toward fiscal expansion.

In Europe, the ECB's Executive Board is turning over: Vice-President de Guindos's term ended in May 2026, and Chief Economist Lane (May 2027), President Lagarde (October 2027) and Isabel Schnabel (December 2027) follow. This gives EU governments an unusual window to reshape the ECB's leadership, with implications for how the central bank manages the tension between accommodative policy for growth and discipline against fiscal free-riding.

The competitive dynamic matters for allocators. As the US lowers effective tax rates through OBBBA, European and Asian economies face pressure to match, creating a global fiscal expansion race where governments compete for capital through deficit-financed incentives. G-7 countries outside the US are now projecting increased fiscal spending, attempting to narrow the gap with the American playbook.