DGB-FX v1.2 — A Practical, Explainable Fair-Value Compass for the 7 Major Currency Pairs

Author: Dr. Glen Brown • Date: August 12, 2025

Executive Summary

DGB-FX adapts an equity-style valuation framework to currencies and blends three anchors: PPP (long-run price-level gravity), REER (multilateral competitiveness), and IRP (carry via 1-year yields). Around that, we run a regime-aware engine (trend/mean-reversion mix), add macro tilts (current-account, growth), and apply a Margin of Safety to protect against model error.

Think of it as a compass for where value lies over ~12 months — not a trade entry timer. Execution still needs your regime filters and risk management.

What “Fair Value” Means in FX (and why three anchors)

Unlike a stock, a currency has no cash flows. Value emerges from relative macro strength and prices. Each anchor answers a different question:

• PPP: “Are baskets of goods/services priced similarly across countries?” If not, the FX rate is doing extra work. PPP is slow-moving and powerful over long arcs.
• REER: “Is this currency competitively expensive/cheap versus its trading partners?” We use the BIS index and interpret deviation vs a long-run mean as a tilt.
• IRP: “What does carry/hedging pressure imply over a year?” We proxy with 1-year government yields for a clean, liquid read.

When PPP, REER, and IRP agree, conviction rises. When they disagree, the blend hedges model risk and keeps us honest.

The Regime-Aware PPP Engine — Explained without equations

1. Annualize the deviation over a short history (e.g., 7 months). This yields a baseline pace of how the gap might evolve.
2. Create regimes (bull/base/bear) by modulating that pace up or down (Fibonacci multipliers). It’s like asking: “What if momentum accelerates? What if it fizzles?”
3. Layer macro tilts: current-account and growth spreads.
4. Probability-weight the three scenarios and apply a Margin of Safety (MOS) haircut to stay conservative.

The MOS-adjusted result is our PPP-engine fair value. We then blend it with IRP (1-yr yields) and REER (deviation tilt).

REER & IRP — Why this version (v1.2) feels “right”

IRP using 1-year yields better reflects investable forward pricing and hedging flows than policy rates alone. We like the 1-year tenor because it’s liquid and matches our horizon.

REER as a deviation vs mean avoids the trap of treating today’s level as “truth.” If a currency’s REER sits far above its long-run average, we assume a mild headwind to further appreciation; if below, a mild tailwind. We use a simple λ parameter to control how strong the tilt is.

Structural premia (e.g., CHF, JPY) acknowledge safe-haven demand that vanilla PPP/REER can understate. We keep premia small (1–2%) and transparent.

One-Year Fair Values (as of Aug 12, 2025)

Rounded results. Negative mispricing = final FV below spot (base currency overvalued).

Pair	Spot	PPP	FV_MOS	IRP (1y)	REER tilt	Final FV	Mispricing
EURUSD	1.1645	1.3500	0.8943	1.1418	1.1896	1.0752	−7.7%
GBPUSD	1.3450	1.4706	1.0922	1.3440	1.3135	1.2499	−7.1%
USDJPY	147.6600	95.1100	300.0841	152.5099	122.8767	194.7009	+31.9%
USDCHF	0.8086	0.9500	0.5584	0.8400	0.7886	0.7436	−8.0%
USDCAD	1.3747	1.1420	1.8302	1.3913	1.3065	1.5093	+9.8%
AUDUSD	0.6529	0.7303	0.5334	0.6496	0.6636	0.6155	−5.7%
NZDUSD	0.5960	0.6849	0.4466	0.5914	0.6086	0.5489	−7.9%

Charts

Each panel shows Spot, PPP, MOS (PPP-engine), IRP (1-yr yields), REER deviation tilt, and the final blend.

Pair-by-Pair Commentary

EURUSD — PPP tailwind, IRP headwind, modest REER lift

Narrative: PPP argues the euro remains undervalued vs the dollar, but carry still leans USD. REER is only mildly supportive for EUR. Our blend lands ~8% below spot — a light downside bias for EUR vs USD unless rates converge faster than expected.

GBPUSD — Near-neutral carry; REER says “a bit rich”

Narrative: Sterling’s carry edge has faded. With REER not obviously cheap and PPP only a mild tailwind, our blend sits ~7% under spot. We read that as balanced-to-soft GBP vs USD, pending UK growth/data surprises.

USDJPY — The big divergence

Narrative: PPP sees JPY as very cheap; IRP still favors USD given the yield gap. We apply a small JPY safe-haven premium and REER tilts, yet the valuation remains well above spot. Translation: the value wind points to higher USDJPY, but timing is treacherous.

USDCHF — Safe-haven gravity intact

Narrative: Switzerland’s structural surplus and high price level justify a bias to a stronger CHF over time. IRP leans USD, but the REER/PPP combo and a small CHF premium pull USDCHF lower on our blend (~8% below spot).

USDCAD — Carry supports USD; PPP pushes back

Narrative: PPP says the USD is expensive vs CAD, but IRP plus our engine point the other way, yielding a ~10% premium to spot. Commodities (oil) and Canada’s CA can swing this quickly; consider terms-of-trade as a future factor.

AUDUSD — Cyclical beta, modest downside bias

Narrative: A softer growth pulse and near-term carry disadvantage leave AUD a touch expensive on our blend (~6% under spot). China demand and RBA posture are the big swing variables.

NZDUSD — Similar story to AUD, with thinner liquidity

Narrative: With limited carry support and no strong REER case, NZD screens ~8% rich on our blend. As always, thin liquidity can exaggerate swings relative to fundamentals.

About the Author — Dr. Glen Brown

Dr. Glen Brown is the President & CEO of Global Accountancy Institute, Inc. and Global Financial Engineering, Inc., closed proprietary trading and research organizations focused on multi-asset strategies. Dr. Brown designs valuation frameworks and regime-aware execution systems that integrate macroeconomics, quantitative modeling, and risk engineering.

Research & Frameworks

• DGB-FX — a multi-anchor FX valuation model blending PPP, REER, and IRP with regime weighting and a Margin-of-Safety lens.
• GATS — Global Algorithmic Trading System; regime confirmation & signal gating for execution.
• DAATS — Dynamic Adaptive ATR Stops; risk overlays for adverse selection and volatility shocks.
• Nine-Laws — a practical operating philosophy for portfolio construction, scenario thinking, capital protection, and iteration.

Focus Areas

• Valuation models for FX, index futures, fixed income, and commodities
• Risk-aware portfolio design: convexity, drawdown control, regime shifts
• Macro data assimilation: current-account, growth, inflation, policy, and terms-of-trade
• Research tooling: reproducible workflows in Python/Excel; audit trails; versioned parameters

Operating Model

Global Accountancy Institute, Inc. and Global Financial Engineering, Inc. operate a closed proprietary model: no client solicitation, no external funds. Publications are intended for internal research, training, and education.

Disclaimers & Disclosures

Educational Content

This publication is provided for educational and research purposes only. It is not investment, legal, tax, or accounting advice and should not be relied upon to make investment decisions.

Market Risk

• Trading foreign exchange and derivatives involves substantial risk of loss and is not suitable for all investors.
• Leverage can work against you; losses may exceed initial capital in certain instruments.
• Past performance, hypothetical or backtested results do not guarantee future outcomes.

Model Risk & Data Limitations

• The DGB-FX model depends on inputs (PPP, REER, yields, current-account and growth data). Revisions and measurement error can change outputs materially.
• Assumptions (e.g., elasticities, regime probabilities, MOS) are tunable and subject to model risk.
• Scenario illustrations and charts are for demonstration; they are not guarantees or recommendations.

Conflicts & Independence

• Global Accountancy Institute, Inc. and Global Financial Engineering, Inc. are proprietary entities and may hold positions in the instruments and assets discussed.
• No compensation has been received from issuers or counterparties in relation to this publication.

No Solicitation

This content does not constitute an offer to sell or a solicitation of an offer to buy any security, investment product, or service. The organizations do not accept external clients or funds.

Forward-Looking Statements

Statements about expected returns, risk, or market conditions are forward-looking and inherently uncertain. Actual outcomes may differ materially.

Jurisdiction & Distribution

Distribution may be restricted by law in certain jurisdictions. If you access this content, you are responsible for compliance with applicable local regulations.

Intellectual Property

© Global Accountancy Institute, Inc. and Global Financial Engineering, Inc. All rights reserved. “DGB-FX”, “GATS”, “DAATS”, and “Nine-Laws” are proprietary frameworks. You may not reproduce or redistribute this content without written permission.