Macroeconomics — National Accounts, Classical, Keynesian, RBC, New Keynesian, Growth, Monetary, Fiscal, Open Economy, Financial Cycles

Macroeconomics

1. At a glance

Macroeconomics is the study of economy-wide aggregates — output, employment, inflation, interest rates, exchange rates, the trade balance, government debt — and of the systematic forces that move them together over business cycles + decades. Microeconomics begins from individual optimisation under constraint and aggregates upward. Macroeconomics starts from aggregate data + identities + theoretical models that aspire to consistency with both microeconomic foundations and the observed time-series dynamics of nations.

The discipline rests on three pillars. National income accounting provides the measurement language — Gross Domestic Product, Gross National Income, Net Domestic Product, the BEA NIPA tables, BLS price + employment data, IMF World Economic Outlook + World Bank WDI cross-country aggregates. Business cycle theory explains short-run fluctuations — from the classical full-employment view through the Keynesian sticky-price multiplier framework, the neoclassical synthesis, real business cycle (RBC) theory, and modern New Keynesian dynamic stochastic general equilibrium (DSGE). Growth theory explains long-run output trajectories — Solow capital deepening, Romer endogenous growth via ideas, Schumpeterian creative destruction, Acemoglu-Robinson institutional explanations.

This note is the canonical macro reference for the library — organised around the standard sequence: measurement → classical baseline → Keynesian + neoclassical synthesis → RBC + New Keynesian + DSGE → growth → monetary economics → fiscal policy → open economy → financial cycles. It pairs with macroeconomics-foundations (a complementary deep note, more empirically oriented), monetary-economics-and-banking (central banks + financial intermediation), public-economics-and-taxation (fiscal detail), and the microeconomics note for theoretical foundations.

Three reference texts anchor modern graduate study: Romer Advanced Macroeconomics (5th ed 2018) for the standard graduate text; Williamson Macroeconomics (6th ed 2017) for intermediate; Galí Monetary Policy, Inflation, and the Business Cycle (2015 2nd ed) for the canonical New Keynesian treatment; Acemoglu Introduction to Modern Economic Growth (2008) for growth theory; Sargent + Ljungqvist Recursive Macroeconomic Theory (4th ed 2018) for dynamic programming methods.

2. National income accounting

2.1 GDP and measurement conventions

Gross Domestic Product (GDP) — the market value of all final goods and services produced within a country in a period, before depreciation. Three measurement approaches, by accounting identity equal in concept:

• Production / value-added approach: GDP = Σ value-added by all sectors.
• Expenditure approach: GDP = C + I + G + (X − M), where C = consumption, I = gross investment, G = government consumption + investment, X = exports, M = imports.
• Income approach: GDP = compensation of employees + corporate profits + proprietors’ income + rental income + net interest + indirect taxes + depreciation (the “gross” in gross domestic product).

The three approaches differ only by statistical discrepancy in measurement.

Gross National Income (GNI) / Gross National Product (GNP) = GDP + net income from abroad (interest, dividends, remittances received minus those paid). GDP is geographic (within the country); GNI is national (to the country’s residents regardless of where earned).

Net Domestic Product (NDP) = GDP − consumption of fixed capital (depreciation). Closer to true economic income because it excludes the depreciation that must be replaced just to maintain the capital stock.

Real vs nominal: nominal GDP uses current-year prices; real GDP deflates with a price index to a base year. GDP deflator = nominal GDP / real GDP × 100. Chain-weighted indices (BEA since 1996) update weights each period to reduce substitution bias.

Price indices: BEA GDP deflator, BLS Consumer Price Index (CPI-U headline + core), BLS Producer Price Index (PPI, intermediate + final demand), BLS Employment Cost Index (ECI, compensation), BEA Personal Consumption Expenditures (PCE) price index — the Fed’s preferred inflation gauge since 2000, particularly core PCE excluding food + energy.

Employment: BLS Current Population Survey (household survey: unemployment rate U-3 + U-6 + labour force participation rate), Current Employment Statistics (establishment survey: payroll employment + average hourly earnings). JOLTS for job openings + quits + hires. Unemployment definitions: U-3 (official rate — actively seeking work in last 4 weeks), U-6 (includes marginally attached + part-time-for-economic-reasons).

2.2 Measurement institutions

US:

• Bureau of Economic Analysis (BEA) within Department of Commerce — NIPA tables (National Income and Product Accounts), regional accounts, industry accounts, international transactions.
• Bureau of Labor Statistics (BLS) within Department of Labor — CPI + PPI + Employment + JOLTS + Productivity.
• Federal Reserve — Industrial Production index, capacity utilisation, Senior Loan Officer Opinion Survey (SLOOS), Beige Book.
• Census Bureau — retail sales, housing starts, durable goods, business formation.

International:

• IMF World Economic Outlook (April + October annually) — cross-country forecasts + International Financial Statistics.
• World Bank World Development Indicators — cross-country GDP + capita + labour + capital data.
• OECD Statistics — OECD member-country harmonised data.
• Eurostat — EU harmonised data.
• Penn World Table — long-run cross-country GDP + factor input + price-level data.
• Maddison Project — long-run historical GDP per capita going back to year 1.

2.3 GDP critiques and alternatives

GDP excludes household production, environmental degradation, depreciation of natural capital, distribution, and well-being beyond market consumption. Alternative + supplementary measures:

• Genuine Progress Indicator (GPI) — adjusts for environmental + social factors.
• Human Development Index (HDI) — UNDP composite of life expectancy + education + GNI per capita.
• Better Life Index (OECD) — multi-dimensional well-being.
• Wealth accounts (World Bank) — broader produced + natural + human capital wealth.
• Stiglitz-Sen-Fitoussi report 2009 — recommendations for moving beyond GDP.
• EPA + UK + EU natural capital + ecosystem-service accounts — System of Environmental-Economic Accounting (SEEA, UN 2012).

3. Classical model and the quantity theory

The pre-Keynesian baseline. Output is determined by the production function Y = F(K, L, A) with capital K, labour L, technology A, at full employment. Wages + prices flex to clear labour + goods markets continuously. Money is neutral in the long run — affects only the price level, not real variables.

Quantity theory of money (Fisher 1911 + monetarist tradition): MV = PY, where M is money supply, V is velocity of circulation, P is price level, Y is real output. With V + Y exogenously determined, ΔM → ΔP one-for-one.

Classical dichotomy: real variables (Y, real wage, real interest rate) determined separately from nominal variables (P, nominal wage, nominal interest rate). Money is a veil.

Say’s law: “supply creates its own demand” — production generates income equal to its value, which is spent, clearing the goods market. Implies no general overproduction.

Wicksell’s natural rate (1898 Interest and Prices): the real interest rate that prevails when output is at potential + savings = investment at full employment. Modern central banks target the policy rate against an estimated “natural” or “neutral” rate (r*); the gap between the policy rate and r* is the stance of monetary policy.

The classical view dominated macroeconomic thinking until the 1930s. The Great Depression — sustained output gap + 25% US unemployment by 1933 + simultaneous deflation — exposed the classical baseline’s empirical inadequacy at business-cycle frequency, motivating Keynes.

4. Keynesian revolution

4.1 Keynes 1936

Keynes 1936 The General Theory of Employment, Interest and Money. Central propositions:

• Sticky nominal prices + wages in the short run mean that labour + goods markets do not clear continuously. Output is demand-determined when prices don’t adjust.
• Aggregate demand drives short-run output: Y = C + I + G + (X − M). Shifts in any component shift output even with flexible factors of production.
• Multiplier effect: an exogenous shift ΔG generates ΔY > ΔG because the additional government spending becomes household income, a fraction of which is re-spent, multiplied iteratively. Simple multiplier = 1/(1 − MPC), where MPC is marginal propensity to consume.
• Animal spirits drive investment + asset markets in ways that pure optimisation cannot capture; expectations are partly self-fulfilling.
• Liquidity preference + paradox of thrift — at the zero lower bound on interest rates, higher saving lowers aggregate demand and reduces income, reducing savings further (the paradox).
• Policy implication: counter-cyclical fiscal + monetary policy stabilises aggregate demand around full employment. Government has both the capacity + responsibility to act in recession.

4.2 IS-LM

Hicks 1937 + Hansen — formalised Keynes into a two-curve graphical model:

• IS curve — combinations of (Y, r) where the goods market clears (Investment = Saving). Downward-sloping in (Y, r) space: higher real interest rate r reduces investment, reducing Y.
• LM curve — combinations of (Y, r) where the money market clears (Liquidity demand = Money supply). Upward-sloping in (Y, r) space: higher Y raises money demand, raising r at given M.

Equilibrium at IS-LM intersection. Comparative statics:

• Expansionary fiscal (ΔG > 0 or ΔT < 0) shifts IS right → higher Y + higher r.
• Expansionary monetary (ΔM > 0) shifts LM right → higher Y + lower r.
• Crowding out: the higher r from fiscal expansion reduces I, partially offsetting the multiplier.
• Liquidity trap: at zero r (zero lower bound) the LM curve is flat in r; monetary policy is impotent and fiscal policy has full multiplier.

IS-LM was the standard intermediate-macro framework from the 1940s through ~1970, joined with AS-AD (aggregate supply + aggregate demand) and Phillips curve.

4.3 Phillips curve

Phillips 1958 documented a negative relationship between UK wage inflation + unemployment over 1861-1957. Samuelson + Solow 1960 extended to US + price inflation + suggested a stable trade-off — policymakers could choose a point on the curve.

Friedman 1968 + Phelps 1967 critique: the trade-off depends on expected inflation. In the long run, with expectations adjusting, the Phillips curve is vertical at the natural rate of unemployment (NAIRU) — there is no long-run trade-off. Attempts to exploit the short-run trade-off generate accelerating inflation (the accelerationist hypothesis).

1970s stagflation — high inflation + high unemployment simultaneously — empirically vindicated Friedman-Phelps + motivated the rational expectations revolution.

Modern Phillips curve debates:

• The curve has flattened sharply post-1990 in advanced economies — the slope coefficient relating inflation to unemployment / output gap is close to zero in many estimates 2010-2020.
• Bernanke + Blanchard 2023 decomposition of post-COVID inflation: shocks to energy + supply chains + labour markets + monetary policy + expectations.
• Anchored expectations as channel: central banks credibly committed to inflation targets keep long-run expectations stable, flattening the short-run Phillips curve.

5. Neoclassical synthesis and the rational expectations revolution

The neoclassical synthesis (1950s-60s, Samuelson + Solow + Hansen + Tobin et al.) combined Keynesian short-run aggregate demand with classical long-run full employment. Short-run output is demand-determined; long-run output is determined by labour + capital + technology at full employment. Counter-cyclical demand management closes short-run output gaps.

The rational expectations revolution (Muth 1961; Lucas 1972, 1976) challenged the synthesis. Central propositions:

• Expectations are formed using all available information including knowledge of the model itself.
• Lucas critique (1976) — econometric policy-evaluation exercises that hold structural parameters fixed across policy changes are invalid, because agents’ expectations + decision rules adjust to the new policy.
• Anticipated monetary policy is neutral (Lucas-Sargent-Wallace policy-ineffectiveness proposition under rational expectations + market clearing); only unanticipated shocks affect real output.

Lucas 1995 Nobel for rational expectations + Lucas critique + business cycle theory. Sargent 2011 Nobel for empirical implementation. Prescott 2004 Nobel for real business cycles.

6. Real business cycle (RBC) theory

Kydland + Prescott 1982 Time to Build and Aggregate Fluctuations (Econometrica) — foundational paper. Joint 2004 Nobel for time consistency + RBC.

Central claims:

• Business cycles can be explained by real shocks (productivity, fiscal, technology) propagating through an optimising representative agent’s intertemporal substitution decisions.
• No need for sticky prices, money, or demand-management policy.
• Calibration approach — set parameters to match long-run averages + microeconomic estimates rather than estimate them statistically; compare model simulations to data moments (output volatility, employment volatility, persistence).

Standard RBC features:

• Representative agent maximising lifetime utility from consumption + leisure.
• Cobb-Douglas production with capital + labour + stochastic technology shock.
• Competitive markets with flexible prices + wages.
• TFP shocks calibrated as AR(1) process with ρ ≈ 0.95 + σ chosen to match output volatility.

Critique:

• TFP shocks calibrated to match output volatility implicitly assume that TFP fluctuations of the calibrated magnitude actually occur — but where do recurring 1-2% quarterly productivity drops come from?
• Money + monetary policy clearly affect real variables in event-study + identified-VAR evidence (Romer + Romer 1989, 2004 narrative identification).
• Cyclical movements in labour are driven mostly by hours per worker + employment rather than by intertemporal substitution by individual workers.

RBC is now subsumed under New Keynesian DSGE as the flexible-price benchmark, with sticky-price + nominal-rigidity extensions added.

7. New Keynesian DSGE

The New Keynesian framework combines:

• Microfounded optimisation + rational expectations (from RBC),
• Monopolistic competition + sticky nominal prices (the “Keynesian” element),
• Stochastic shocks (productivity, demand, monetary policy).

Calvo (1983) pricing — fraction (1 − θ) of firms reset price each period; remaining θ keep last period’s price. Yields the New Keynesian Phillips Curve (NKPC):

π_t = β E_t π_{t+1} + κ · output_gap_t + cost_push_shock_t

where κ depends on Calvo parameter θ, discount factor β, and labour-market parameters.

Taylor pricing (Taylor 1980) — alternative staggered-contracts model with fixed N-period overlapping contracts; yields similar NKPC dynamics.

Three-equation New Keynesian model (textbook Galí 2015):

1. IS equation (forward-looking, microfounded from Euler equation): output_gap_t = E_t output_gap_{t+1} − (1/σ)(i_t − E_t π_{t+1} − r_t) where σ is intertemporal elasticity of substitution, ris natural real rate, i_t is nominal policy rate.

2. NKPC (above).

3. Taylor rule (Taylor 1993) — central bank reaction function: i_t = r*+ π_t + φ_π (π_t − π*) + φ_y output_gap_t with Taylor principle φ_π > 1 ensuring determinacy + inflation control.

Solving the system yields a forward-looking dynamic equilibrium responding to demand + supply + monetary policy + cost-push shocks.

Estimated DSGE models — Smets + Wouters 2007 (Euro Area + US); Christiano + Eichenbaum + Evans 2005; FRB Reserve banks’ models; ECB’s New Area-Wide Model. Standard for central-bank forecasting + counterfactual analysis 2000-present.

Critique:

• DSGE handled the 2008 crisis poorly: standard models had no financial sector + no role for credit + no zero-lower-bound mechanism.
• Heterogeneous-Agent New Keynesian (HANK — Kaplan + Moll + Violante 2018) addresses some critiques by modelling income + wealth heterogeneity + idiosyncratic income risk.
• Post-2010 generation includes financial frictions (Gertler + Karadi 2011; Bernanke + Gertler + Gilchrist 1999 financial accelerator), zero-lower-bound forward guidance, fiscal multipliers at the ZLB (Christiano + Eichenbaum + Rebelo 2011; Eggertsson + Krugman 2012).

8. Growth theory

8.1 Solow model

Solow 1956 (QJE) + Swan 1956. Workhorse of long-run growth analysis. Production function with capital + labour + technology:

Y = F(K, AL)  =  A · K^α · L^(1−α)  (Cobb-Douglas case)

with constant returns to scale + diminishing marginal product of capital. Capital accumulation: K̇ = sY − δK, savings s exogenous, depreciation δ.

Steady state: K/L grows at exogenous rate of technological progress g_A; output per worker grows at g_A; capital-output ratio K/Y constant. Conditional convergence: countries with lower K/Y grow faster in transition to steady state, conditional on same parameters.

Solow residual = TFP growth — the residual after accounting for measured K + L. Cross-country variation in income is dominated by TFP differences, not factor accumulation differences (Caselli 2005; Hsieh + Klenow 2010).

Solow 1987 Nobel for growth theory.

8.2 Endogenous growth

The Solow model’s exogenous technology growth is unsatisfying — what determines g_A?

Romer 1990 (JPE) — Endogenous Technological Change. Ideas + non-rivalry. Firms invest in R&D to develop new varieties, which raise aggregate productivity. Romer 2018 Nobel (shared with Nordhaus). Implications:

• Ideas are non-rival (one country’s use doesn’t deplete another’s) → increasing returns at the aggregate level.
• Patents + monopoly markup over R&D cost is necessary to fund R&D — endogenous monopolistic competition.
• Subsidising R&D + education raises long-run growth.

Lucas 1988 (Journal of Monetary Economics) — On the Mechanics of Economic Development. Human capital accumulation drives growth.

Schumpeterian growth (Aghion + Howitt 1992; Aghion + Howitt 1998 + 2009 The Economics of Growth) — quality ladders + creative destruction. New innovations replace existing technology. Aghion + Howitt + Akcigit + Klette + Kortum subsequent literature.

8.3 Institutions

Acemoglu + Robinson + Acemoglu + Johnson + Robinson (2001, 2002, 2005, 2012, 2024). Acemoglu + Johnson + Robinson 2024 Nobel.

Central claim: institutions (the rules of the game, broadly construed — property rights, contract enforcement, political accountability, inclusivity) explain the bulk of cross-country variation in long-run prosperity. Geography + culture matter, but they matter through institutions.

Key empirical work:

• AJR 2001 The Colonial Origins of Comparative Development — settler mortality as instrument for institutional quality.
• AJR 2002 Reversal of Fortune — the rich pre-colonial areas (Mughal India, Aztec Mexico) became the poor post-colonial areas as colonial institutions were imposed to extract rents rather than invest.
• Acemoglu + Robinson 2012 Why Nations Fail — book-length argument for inclusive vs extractive institutions.
• Acemoglu + Robinson 2019 The Narrow Corridor — state capacity + civil society constraints.

Critique + alternative views:

• North 1990; North + Wallis + Weingast 2009 — institutions as informal rules + organisations + history.
• Mokyr 2002, 2009, 2017 — culture + Enlightenment + scientific revolution as drivers.
• Diamond 1997 + Pomeranz 2000 — geography + ecology + resource endowments.
• Allen 2009 — high wages + cheap energy as British Industrial Revolution driver.

8.4 Growth empirics

Mankiw + Romer + Weil 1992 — augmented Solow with human capital fits cross-country data reasonably; explains ~80% of cross-country income variation conditional on investment + population growth + initial conditions.

Penn World Table + Maddison Project — long-run cross-country GDP data. The “Great Divergence” (Pomeranz 2000 terminology) starting ~1500-1800: Western Europe + offshoots pull away from China + India + Ottoman + Africa. The “Great Convergence” (Baldwin 2016) starting ~1990: emerging Asia + parts of Latin America + Eastern Europe close gap to advanced economies, driven by trade + technology diffusion + ICT.

China’s rise (1978 reforms onward + WTO 2001): GDP per capita from <$200(1978)to>$12,000 (2024). Hsieh + Klenow 2009 on misallocation as a measure of how far China + India remained from US TFP frontier.

9. Monetary economics

9.1 Money supply

Definitions (US Federal Reserve):

• M1 — currency + demand deposits + checkable deposits + traveler’s checks + savings deposits (since May 2020 reclassification).
• M2 — M1 + small time deposits + retail money-market funds. The Fed’s primary money aggregate post-2020.
• M3 — historical aggregate including large time deposits + institutional MMFs; discontinued 2006.

Reserve aggregates — bank reserves at the Fed (interest on reserve balances paid since 2008, formerly required reserves + excess reserves). Reserve requirements set to zero March 2020 + remain zero. Ample reserves regime since 2008.

Money multiplier = M / Monetary Base. Pre-2008, multiplier ~10 in the US (10 dollars of M2 per dollar of base). Post-2008 with massive QE-expanded reserves, multiplier collapsed to ~3-4. The classical fractional-reserve textbook story is empirically obsolete in the ample-reserves regime.

9.2 Central bank operations

US Federal Reserve:

• Federal Open Market Committee (FOMC) — 12 voting members (7 Governors + NY Fed President + 4 rotating Reserve Bank Presidents) meeting 8 times/year. Sets the federal funds target range + balance sheet decisions.
• Open market operations — purchases + sales of Treasury securities + agency MBS by the New York Fed Markets Group, implementing the FOMC’s target. In the ample-reserves regime, the administered rate (Interest on Reserve Balances, IORB) is the primary policy rate; Overnight Reverse Repo (ON RRP) rate sets a floor.
• Discount window — emergency liquidity at primary credit rate (above IORB).
• Standing Repo Facility — overnight repo against Treasury + agency MBS collateral, established July 2021 to ensure rate-floor mechanics.
• Forward guidance — communications about future policy path (calendar-based or state-contingent).
• Quantitative easing (QE) + quantitative tightening (QT) — large-scale asset purchases / sales as policy when funds rate is at zero lower bound (QE 1-4 between 2008-2014 + COVID-era 2020-22) or to manage reserve supply (QT 2017-19 + 2022+).

ECB:

• Governing Council — 6 Executive Board members + 20 national central bank governors (rotating voting since 2015) meeting every 6 weeks.
• Policy rates: Deposit Facility Rate (DFR) (primary policy rate post-2008), Main Refinancing Operation (MRO) rate, Marginal Lending Facility (MLF) rate.
• TLTRO (Targeted Longer-Term Refinancing Operations) — collateralised lending to banks conditional on lending to non-financial private sector.
• APP + PEPP — Asset Purchase Programme (2014+) + Pandemic Emergency Purchase Programme (2020-22).

BoE:

• Monetary Policy Committee (MPC) — 9 members (Governor + 3 Deputy Governors + Chief Economist + 4 external members) meeting 8 times/year.
• Bank Rate + Asset Purchase Facility.

BoJ:

• Policy Board — 9 members.
• Negative interest rate (-0.10%) regime + yield curve control (10Y JGB target) since 2016. Both ended March 2024 + July 2024 as Japan exited deflation.

PBoC (People’s Bank of China):

• Multiple policy rates: 7-day reverse repo rate, Medium-term Lending Facility (MLF) rate, Loan Prime Rate (LPR).
• Required reserve ratio (RRR) active policy tool; cuts repeatedly through 2022-25.
• Government coordination structure; not independent central bank.

9.3 Taylor rule

Taylor 1993 — simple monetary policy rule that fit Fed policy 1987-92 well:

i_t = r*+ π_t + 0.5(π_t − π*) + 0.5 · output_gap_t

with r*= 2%, π*= 2%. Taylor principle: coefficient on π_t > 1 (here 1 + 0.5 = 1.5) ensures the real interest rate rises with inflation, providing determinacy + stable inflation.

Modern Fed reaction functions — multiple variants (Taylor 1999 expanded; balanced-approach rule; first-difference rule); the Fed’s discussion materials publish ranges from multiple Taylor-rule specifications.

9.4 Inflation targeting

Inflation targeting — central bank publicly commits to a numerical inflation target + uses policy rate to achieve it. Pioneered by New Zealand 1989, Canada 1991, UK 1992, Sweden 1993. Fed adopted explicit 2% PCE inflation target January 2012; revised to 2% average inflation targeting (AIT) August 2020 (Powell Jackson Hole speech) — allows inflation to run above 2% temporarily after periods of undershooting. ECB target “below, but close to, 2%” until July 2021 revision to symmetric 2% target.

Flexible inflation targeting — modern central banks balance inflation + output gap + financial stability + employment under a “dual mandate” (Fed) or single mandate (ECB, BoE, BoJ) interpreted flexibly.

9.5 Zero lower bound and unconventional policy

The 2008 financial crisis pushed the Fed funds rate to ~0-0.25% by December 2008. The European debt crisis pushed ECB rates to zero by 2012 + negative (DFR) from June 2014 to July 2022. BoJ negative -0.10% since January 2016 until March 2024. Swiss National Bank deepest negative -0.75%.

Unconventional tools at the ZLB:

• Quantitative easing (QE) — large-scale purchases of long-dated Treasuries + agency MBS, compressing term premium + lowering long rates.
• Forward guidance — calendar-based (“zero until 2015”) or state-contingent (“zero until inflation is 2% and employment is below threshold”).
• Negative interest rates (ECB, BoJ, SNB, Riksbank, Denmark) — applied to commercial bank reserves at the central bank.
• Yield curve control (BoJ) — explicit cap on 10Y JGB yield (0.0% ± 25 bp, raised + finally abandoned 2022-24).
• Lending facilities — TLTRO (ECB), Term Auction Facility (Fed 2007-10), Term Funding Scheme (BoE), Funding for Lending Scheme (BoE).
• Liquidity swap lines — between Fed + foreign central banks (ECB, BoE, BoJ, SNB, BoC, etc.) — emergency dollar funding for foreign banks.

9.6 Post-COVID monetary policy

2020-26 cycle. COVID shock March 2020 → Fed cut to 0-0.25% + QE5 ($4T+Treasury+MBSexpansion2020-22).Fiscalexpansion($5T+ across CARES + ARP + IIJA + IRA + CHIPS). Supply chain disruption + Russia-Ukraine war (Feb 2022) → US CPI peaked 9.1% June 2022. Fed hiked aggressively March 2022 - July 2023, from 0-0.25% to 5.25-5.50% (525 bp in 16 months — the fastest tightening cycle since Volcker). Held through August 2024, eased 100 bp September-December 2024 (50 bp first cut Sept 2024 + 25 bp Nov + Dec). Paused 2025; resumed cutting H2 2025 as inflation moved toward 2% target + labour market loosened. Core PCE ran 2.5-3.0% through 2024-25, gradually approaching target.

ECB followed similar trajectory: DFR from -0.50% (mid-2022) to 4.00% (Sept 2023), held through mid-2024, eased to 2.50-3.00% by end-2025. BoE Bank Rate from 0.10% to 5.25% (Aug 2023), eased to 3.50% by end-2025.

10. Fiscal policy

10.1 Multipliers

Fiscal multiplier = ΔY / ΔG (or ΔY / ΔT for tax multiplier). Simple textbook formula: 1/(1 − MPC). With MPC = 0.7, multiplier = 3.33.

Empirical multipliers much smaller in practice (typically 0.5-1.5 in normal times):

• Standard Vector Autoregression (Blanchard + Perotti 2002): government spending multiplier ~1.0 + tax multiplier ~1.3.
• Narrative + structural-VAR identification (Romer + Romer 2010 tax narrative): tax-cut multiplier ~3 at long horizons.
• Local-multiplier studies (Nakamura + Steinsson 2014 cross-state defence spending): multiplier ~1.5.

Multiplier at the ZLB — substantially larger than in normal times. Christiano + Eichenbaum + Rebelo 2011 + Eggertsson + Krugman 2012 + DeLong + Summers 2012: multiplier 2-3 at ZLB because (a) no monetary offset (Fed cannot cut further); (b) deficits not crowding out private investment with policy rate stuck at zero; (c) hysteresis prevents return to potential. The 2009 ARRA + 2020-22 CARES + ARP fiscal packages operated under ZLB conditions for substantial portions of their disbursement window.

10.2 Debt sustainability

Debt dynamics identity:

ΔD/Y = (r − g) · D/Y + primary_deficit/Y

where D is government debt, Y is GDP, r is real interest rate on debt, g is real GDP growth, primary deficit = total deficit excluding interest.

Debt is stable when:

• (r − g) < 0: real interest rate below growth rate → debt-to-GDP falls automatically even with small primary deficit.
• Primary surplus offsets (r − g) > 0.

US debt trajectory: federal debt held by public ~$28T in 2025 (~100% of GDP). CBO projections show rising to 122% by 2034 absent policy change; structural primary deficit ~5% of GDP driven by Social Security + Medicare + Medicaid + debt interest as boomers retire + healthcare inflation persists. Major debt sustainability debate underway in 2024-26 with Trump administration tax + tariff + spending choices + CBO baseline updates.

Fiscal theory of price level (FTPL) — Sims + Cochrane + Leeper tradition. Government’s intertemporal budget constraint determines the price level; fiscal dominance can override monetary policy. Relevant when (r − g) approaches positive territory + monetary policy faces fiscal constraints. Active research area 2022-26 given large post-COVID fiscal positions globally.

10.3 Automatic stabilisers vs discretionary

Automatic stabilisers — tax + transfer programmes that respond automatically to the business cycle:

• Progressive income tax — revenue falls more than proportionally with income in downturn.
• Unemployment insurance — benefits rise automatically when unemployment rises.
• SNAP + EITC + Medicaid — counter-cyclical eligibility + benefits.

Estimated to dampen US output volatility by ~10-20%; Europe higher due to larger welfare state.

Discretionary fiscal policy — counter-cyclical spending + tax cuts enacted by legislation. Subject to political + implementation lags. Modern view (post-Romer + Romer 2010, post-2008 + 2020 experience): can be effective particularly at ZLB or in deep recessions; less reliable in normal times because of timing + political constraints.

10.4 Modern fiscal frameworks

• EU Stability and Growth Pact — 3% deficit + 60% debt ceiling, often breached + reformed (2024 reforms shifted to net-expenditure path frameworks).
• UK Charter for Budget Responsibility + OBR fiscal forecasts.
• US debt ceiling — periodic crisis flashpoint; doesn’t impose actual fiscal constraint but produces political stress (2011, 2023 most recent serious episodes; debt-ceiling suspension June 2023 deal through Jan 2025).
• Modern Monetary Theory (MMT) — Kelton + Wray + Tcherneva + Mosler. Claims that monetary-sovereign government’s spending is constrained only by inflation, not by debt-financing. Mainstream macro (Krugman, Mankiw, Summers, Blanchard) disputes some MMT claims but acknowledges intellectual point that monetarily-sovereign government with debt in its own currency does not face hard budget constraint in the same way as Eurozone members or emerging markets with FX-denominated debt.

11. Open economy

11.1 Balance of payments

Balance of payments = current account + capital account + financial account (with statistical discrepancy). By accounting identity, current account + capital + financial accounts sum to zero.

• Current account = trade balance (X − M) + net income from abroad + net unilateral transfers.
• Financial account = net foreign direct investment + portfolio investment + other investment + reserve assets.

A current-account deficit must be financed by a financial-account surplus (net foreign capital inflows). The US runs persistent current-account deficits financed by foreign demand for US Treasury debt + corporate equity + real estate.

11.2 Exchange rate regimes

• Fixed (pegged) — central bank commits to maintain a specific exchange rate (Hong Kong dollar peg to USD; historical Bretton Woods 1944-71; Argentina convertibility 1991-2001).
• Crawling peg — adjustable peg following a rule (some emerging markets).
• Managed float — central bank intervenes to smooth fluctuations without explicit target (most emerging markets + Switzerland post-2015).
• Free float — exchange rate determined by market with minimal intervention (USD, EUR, JPY, GBP, CAD, AUD, NZD).

11.3 Mundell-Fleming and the impossible trinity

Mundell-Fleming (Mundell 1963; Fleming 1962) — IS-LM extended to open economy with capital mobility. Central insight: under perfect capital mobility, a country cannot simultaneously have:

• Fixed exchange rate,
• Independent monetary policy,
• Free capital flows.

Pick two; the third is determined. The impossible trinity (or trilemma) frames every country’s choice:

• US, EU, UK, Japan: free capital + independent monetary → floating exchange rate.
• Hong Kong, Saudi Arabia, Denmark (ERM II): free capital + fixed exchange rate → no independent monetary policy (HKD currency board).
• China (partially), Malaysia (1998 crisis), Cyprus (2013 crisis): independent monetary + fixed exchange → capital controls.

Mundell 1999 Nobel for optimal currency area + open-economy macro.

11.4 Optimal currency areas

Mundell 1961 Optimum Currency Areas — conditions for sharing a single currency:

• High labour + capital mobility within the area.
• Synchronised business cycles (or fiscal transfers compensating for asynchronous shocks).
• Open trade integration.
• Wage + price flexibility.

The Eurozone (since 1999, 20 members by 2024 with Croatia 2023) has been the laboratory. The 2010-12 European debt crisis exposed gaps — labour mobility limited within EU + no fiscal transfers + asymmetric shocks hit periphery. ECB’s “whatever it takes” (Draghi July 2012) + OMT + later TPI + ESM + Banking Union reforms partially closed the gaps.

11.5 Reserve currencies and dollar dominance

The US dollar’s role as primary reserve currency + invoicing currency + safe-haven asset has structural macroeconomic implications:

• Triffin dilemma — providing global reserve assets requires US current-account deficits, but persistent deficits erode confidence.
• Exorbitant privilege (Giscard d’Estaing 1965) — US borrows cheaply in own currency.
• Gopinath et al. dominant-currency paradigm — global trade priced + invoiced in USD; exchange-rate movements transmit to trade volumes asymmetrically.

Renminbi internationalisation has progressed (CIPS, swap lines, RMB-denominated commodity trades — Russia, Brazil, Saudi Arabia partial) but RMB share of global reserves remains <3% as of 2025. Euro share ~20%. USD share ~58% (down from 70% in 1999 but stable since 2020).

12. Financial cycles and crises

12.1 Minsky and financial fragility

Hyman Minsky 1986 Stabilizing an Unstable Economy + 1992 The Financial Instability Hypothesis. Central claims:

• Stability breeds instability — extended booms encourage rising leverage + speculative positions.
• Three financing positions: hedge (income covers principal + interest), speculative (covers interest, rolls principal), Ponzi (depends on asset appreciation).
• Late-cycle dominance of speculative + Ponzi positions makes the system fragile.
• Minor disturbance triggers debt deflation + asset price collapse — the Minsky moment.

Minsky was outside the macroeconomic mainstream when he wrote; the 2007-09 crisis revived his ideas as a framework for understanding financial fragility.

12.2 Reinhart-Rogoff

Reinhart + Rogoff 2009 This Time Is Different. Eight centuries of financial crises in a single database. Key empirical regularities:

• Banking crises follow rising leverage + capital inflows + asset bubbles in housing + equity.
• Recovery from financial crises is slower than from normal recessions — typically 5-10 years to recover lost output.
• Sovereign debt crises follow banking crises in many cases (private debt becomes public via bailouts).
• Inflation crises in emerging markets historically common when fiscal dominance overwhelms monetary policy.

Reinhart-Rogoff also wrote a controversial 2010 paper (Growth in a Time of Debt) on growth-debt threshold around 90% of GDP, later partly criticised for spreadsheet errors + sample selection (Herndon + Ash + Pollin 2013), but the broader empirical work on crisis history remains influential.

12.3 Modern financial accelerator

Bernanke + Gertler 1989, 1995 + Bernanke + Gertler + Gilchrist 1999 — financial accelerator framework. External finance premium rises with leverage + falls with net worth; recessions reduce net worth, raise the premium, amplifying the downturn.

Gertler + Karadi 2011 — banking sector with capital constraints in New Keynesian DSGE. Unconventional monetary policy (asset purchases) loosens bank balance-sheet constraints, expanding credit.

Brunnermeier + Sannikov 2014 — continuous-time financial-frictions framework with explicit risk-bearing capacity. Endogenous risk + occasional crises arise from the same friction.

Kiyotaki + Moore 1997 — credit cycles with collateral constraints. Negative shock reduces asset values, tightens collateral constraints, amplifies. Standard reference for housing-bubble + collateral-channel modelling.

12.4 2008 crisis and aftermath

US subprime mortgage crisis 2007-08 → Lehman Brothers bankruptcy Sept 15, 2008 → global liquidity crisis + AIG + Fannie + Freddie bailouts + TARP $700B + Fed emergency programmes + extraordinary monetary policy. Bernanke + Diamond + Dybvig 2022 Nobel for bank-run theory + crisis policy.

Dodd-Frank Wall Street Reform and Consumer Protection Act (July 2010) — major reform: Volcker Rule (banks cannot engage in proprietary trading), Consumer Financial Protection Bureau, derivatives clearing (CFTC + SEC), resolution authority (FDIC OLA), stress tests (Fed CCAR), Basel III implementation. Partial rollback under EGRRCPA 2018.

Basel III — Basel Committee on Banking Supervision international standards: Common Equity Tier 1 (CET1) capital ratio minimum + capital conservation buffer + countercyclical buffer + G-SIB surcharge + Leverage Ratio + Liquidity Coverage Ratio + Net Stable Funding Ratio. US implementation via Fed + OCC + FDIC rulemakings 2013-2025. Basel III “endgame” US final rules 2024-25.

12.5 European debt crisis

2010-12 sovereign debt crisis: Greece + Portugal + Ireland + Italy + Spain. Spreads between periphery + German bunds widened > 1,000 bp at peaks. Greek bailouts (May 2010 + Feb 2012 + Aug 2015), Portugal + Ireland EU/IMF programmes, Cyprus 2013 bail-in (depositors > €100K hair-cut), Spanish banking-system recapitalisation. Draghi “whatever it takes” (July 2012) + OMT (announced Sept 2012, never deployed but verbal commitment stabilised spreads) + ESM + Banking Union (Single Supervisory Mechanism Nov 2014 + Single Resolution Mechanism Jan 2016) reforms.

12.6 COVID-19 crisis 2020

March 2020 - global lockdowns + Fed cuts to 0-0.25% + unprecedented fiscal response (CARES Act \$2.2T)+massiveQE5+corporate-bondpurchases(PMCCF+SMCCF)+MainStreetLendingProgram+PaycheckProtectionProgram.OutputcollapsedQ22020(USGDP-31$5T US cumulative through IRA + IIJA), and a monetary expansion (zero rates + QE) of unprecedented magnitude in peacetime.

13. Recent themes (2022-26)

Inflation surge + decline. US headline CPI 1.4% Dec 2020 → 9.1% June 2022 → 2.5% by end-2024 → ~2.3-2.7% range through 2025. Core PCE similar trajectory. Decomposition (Bernanke + Blanchard 2023): early surge driven by energy + supply chains + commodities; persistent component driven by tight labour markets + wage growth; declining inflation reflects supply-chain normalisation + monetary tightening + labour-market loosening.

Soft landing question. As of mid-2026, the Fed achieved a remarkable result by historical standards: inflation falling toward target without a recession + unemployment staying low. Whether this is a soft landing or a delayed-recession scenario remains debated. The Sahm rule (recession indicator based on 0.5 pp rise in 3-month unemployment moving average) triggered briefly in 2024 + then reversed.

Fiscal trajectory. US debt-to-GDP rising; primary deficit ~5% of GDP structural. CBO 10-year projections show debt exceeding 120% by 2034 absent policy change. R-g sign + Treasury auction reception become central. 2024-25 Treasury market stress + foreign demand questions; auction tail patterns + foreign-CB holdings.

AI + productivity. Whether AI raises measured productivity at macro scale is contested. Brynjolfsson et al. + Acemoglu + Restrepo + Korinek + Autor estimates range from 0.3-1.5 pp productivity growth per year incremental. Sectoral early evidence: customer support + writing + software engineering show double-digit task-level gains; aggregate measured productivity less clear. Krueger + Mokyr + Gordon debate on whether AI rivals electricity / computer / Internet as general-purpose technology.

Industrial policy + reshoring. CHIPS + Science Act $52B;IRA$369B nominal; IIJA $1.2T; combined the largest US industrial policy push since the Apollo program. EU Green Deal Industrial Plan + Net-Zero Industry Act + Critical Raw Materials Act. China industrial-policy continued. Whether these policies raise long-run growth or distort allocation is contested + difficult to measure at horizons relevant to the policies.

Demographics + secular trends. Aging populations in advanced economies + China + Korea + parts of Latin America. Implied negative effects on labour-force growth + savings glut + low real interest rates (until 2022 surge) + healthcare + pension costs. Fertility rates well below replacement in Korea (0.7), Japan (1.2), Italy (1.2), Germany (1.4), China (1.0), US (1.6). Immigration as partial offset; political feasibility limited.

Climate macro. Stern Review 2006 (low-discount-rate urgency); Nordhaus DICE (Nordhaus 2018 Nobel) higher-discount-rate gradualism; Weitzman 2009 dismal-theorem fat-tails. EPA 2023 SCC $190/tCO2. Climate macro extending beyond microeconomics: Bansal-Yaron long-run risk + asset pricing under climate uncertainty; central bank stress-testing for climate scenarios (NGFS scenarios — Network for Greening the Financial System); Schnabel ECB + Brainard Fed speeches integrating climate into monetary frameworks.

14. Cross-references

• _index — library index
• macroeconomics-foundations — complementary empirical-orientation deep note
• microeconomics — micro foundations
• monetary-economics-and-banking — money + central banks + intermediation detail
• public-economics-and-taxation — fiscal detail + optimal taxation
• development-economics — long-run growth + emerging markets + RCTs
• econometrics-foundations — VAR + DSGE estimation + time-series methods
• history-of-economic-thought — intellectual history
• environmental-and-resource-economics — climate macro + carbon pricing

15. References

Graduate texts:

• Romer Advanced Macroeconomics 5th ed 2018.
• Acemoglu Introduction to Modern Economic Growth 2008.
• Ljungqvist + Sargent Recursive Macroeconomic Theory 4th ed 2018.
• Galí Monetary Policy, Inflation, and the Business Cycle 2nd ed 2015 — New Keynesian DSGE standard.
• Walsh Monetary Theory and Policy 4th ed 2017.
• Woodford Interest and Prices 2003 — New Keynesian foundations.

Intermediate: Williamson Macroeconomics 6th ed 2017; Mankiw Macroeconomics 11th ed 2022; Jones Macroeconomics 5th ed 2020; Blanchard Macroeconomics 8th ed 2020; Mishkin The Economics of Money, Banking and Financial Markets 13th ed 2022.

Specialty:

• Acemoglu + Robinson Why Nations Fail 2012; The Narrow Corridor 2019.
• Reinhart + Rogoff This Time Is Different 2009.
• Bernanke The Federal Reserve and the Financial Crisis 2013; 21st Century Monetary Policy 2022.
• Eichengreen Globalizing Capital 3rd ed 2019.
• Tooze Crashed 2018; Shutdown 2021.

Foundational papers:

• Keynes 1936 General Theory.
• Friedman 1968 AER (Role of Monetary Policy).
• Phelps 1967 Economica (Phillips curves + expectations).
• Lucas 1972 J Econ Theory (Expectations and the Neutrality of Money); 1976 Carnegie-Rochester (Lucas critique).
• Kydland + Prescott 1982 Econometrica (Time to Build); 1977 JPE (Time inconsistency).
• Romer 1990 JPE (Endogenous Technological Change).
• Aghion + Howitt 1992 Econometrica (Creative destruction).
• Acemoglu + Johnson + Robinson 2001 AER (Colonial origins).
• Calvo 1983 J Monetary Econ (Staggered prices).
• Taylor 1993 Carnegie-Rochester (Taylor rule).
• Mundell 1961 AER (Optimum currency areas).
• Bernanke + Gertler + Gilchrist 1999 Handbook of Macro (Financial accelerator).
• Christiano + Eichenbaum + Rebelo 2011 JPE (Government spending multiplier at ZLB).

Nobel laureates referenced: Friedman 1976; Tobin 1981; Modigliani 1985; Solow 1987; Lucas 1995; Mundell 1999; Heckman + McFadden 2000; Akerlof + Spence + Stiglitz 2001; Kahneman + Smith 2002; Kydland + Prescott 2004; Phelps 2006; Krugman 2008; Williamson + Ostrom 2009; Sims + Sargent 2011; Hansen + Fama + Shiller 2013; Tirole 2014; Deaton 2015; Hart + Holmström 2016; Thaler 2017; Nordhaus + Romer 2018; Banerjee + Duflo + Kremer 2019; Milgrom + Wilson 2020; Card + Angrist + Imbens 2021; Bernanke + Diamond + Dybvig 2022; Goldin 2023; Acemoglu + Johnson + Robinson 2024.