The Interest Rate Determination Mechanism: Multi-Layer Lending Structure and the Central Bank's Quantity-Price Dual Track

Modern interest rates are not a single price but are formed jointly by multi-layer nested lending relationships running from the central bank to the real economy; after 2008, quantitative easing enabled central banks to determine both the money supply (quantity) and the base price of funds (price) simultaneously, giving rise to cyclical transmission through a tailwind phase (Davis Double Play) and a headwind phase (valuation-earnings double kill), with the cycle forcibly interrupted when liquidity becomes excessively abundant and leverage exceeds its limits.

The Framework As It Stands

This section is compiled from research drafts: the original framework’s structure, terminology, and key formulations are preserved, including editorial bridging and supplementary factual annotations; charts are drawn by the compiler following the structure of the original text.

I. The Multi-Layer Nested Lending Structure

Interest rates are not a single price but are formed jointly by multi-layer lending relationships:

flowchart TD
    A[Central Bank] --> B[Major Financial Institutions: Repo / Reverse Repo]
    B --> C[Major Banking System]
    C --> D[Regional Banks / Small Banks / Shadow Banks]
    D --> E[Corporate Sector]
    D --> F[Household Sector]
    E --> G[Real Investment and Credit Demand]
    F --> H[Mortgage / Consumer Loan Demand]

Supply and demand at each layer are highly dynamic, which is why the interest rate determination mechanism is complex.

Taking the U.S. 30-year mortgage as an example, its pricing formula is:

10Y/30Y Treasury Yield + Reasonable Spread + Mortgage Application/Repayment Supply-Demand + Model Hedging / Gamma Demand

This shows that the interest rate embedded in asset pricing is not an abstract policy term but is generated jointly by market indicators, supply and demand, and model behavior.

II. Post-2008: The Central Bank Determines Both Quantity and Price Simultaneously

Before 2008, central banks primarily controlled “price” (the policy rate). After 2008, QE allowed central banks to determine simultaneously:

• Money supply: quantity
• Base price of funds: price

This is the fundamental change in the modern financial system. See The Dual Anchors of Interest Rates and Exchange Rates: A Macro Observation Framework for the Age of High Volatility for the definition of the interest rate anchor entry point.

III. The Central Bank Considers at Least Six Categories of Factors

Factor	Meaning
Inflation level and inflation expectations	Expectations of financial institutions, households, and financial markets
Employment	One of the Fed’s statutory mandates
Price stability	One of the Fed’s statutory mandates
Economic growth	By default must be monitored
Financial stability	Significantly elevated in importance after 2008
Other political / structural factors	Overseas assets, green finance, wealth inequality, inclusive finance, etc.

IV. The Greenspan Put: Institutionalization of the Central Bank Backstop

The Greenspan Put refers to the central bank providing support when markets fall, restoring market stability and an upward trajectory. After 2008, major central banks accumulated more crisis-response tools, and the central bank backstop mechanism became more institutionalized.

V. Tailwind-Phase Transmission Chain: Low Inflation + Weak Economy → Davis Double Play

flowchart LR
    A[Low Inflation + Weak Economy] --> B[Monetary Expansion]
    B --> C[Demand Rises]
    C --> D[Leverage Increases]
    D --> E[Liquidity Rises / M2 Increases]
    E --> F[Asset Prices Rise]
    F --> G[Valuations Expand]
    C --> H[Corporate Earnings Rise]
    G --> I[Davis Double Play]
    H --> I

VI. Headwind-Phase Transmission Chain: High Inflation + Strong Economy → Valuation-Earnings Double Kill

Economy Overheats + High Inflation → Central Bank Tightens Money → Leverage Decreases → Asset Selling
→ Prices Fall → Demand Declines / Economic Downturn Expectations → Valuations Killed First → Earnings Killed Next → Double Kill

VII. Interruption Conditions: Excessive Liquidity Abundance + Leverage Beyond Limits

The natural cycle of tailwind and headwind phases is not easily interrupted. A true interruption typically occurs when:

Liquidity excessively abundant + Leverage exceeds reasonable bounds

The framework emphasizes: cheap liquidity volatility is the trigger; leverage beyond reasonable bounds is the primary cause.

Compiler’s Perspective

Coordinates: Category = Monetary System and Circulation · axis_h = Fa · axis_v = Why It Is So

Connection layer

In the early part of the 2022 rate-hike cycle, the market broadly looked only at the policy rate level (“price”), ignoring that the Fed was simultaneously pressing ahead with balance-sheet reduction compressing the money supply (“quantity”), and continued holding high-valuation growth stocks using the tailwind-phase framework — the error lay in separating “price” from “quantity,” whereas the framework explicitly states that after 2008, both are controlled by the central bank simultaneously. Once liquidity contraction began cutting into the “quantity” dimension, valuations collapsed first, entering the tailwind-phase sequence’s “valuations killed first” stage; it was only when inflation persistently eroded demand that “earnings killed next” followed — the two judgment points for being forced out of positions are entirely different.

The framework’s sole incremental claim: the Greenspan Put is fundamentally the institutional record of “financial stability” shifting from the implicit last position among the central bank’s six factors to the explicit first position — it is not an unconditional backstop promise. The backstop is triggered only when the weight of the financial stability factor overrides the inflation factor; if inflation remains strong (as in 2022), the Put’s room shrinks, and simply betting on a central bank rescue is a misreading of the dynamic weighting among the six factors.

The 30-year mortgage pricing formula (10Y/30Y Treasury + spread + supply-demand + gamma demand) is the numerical anchor verifying that “interest rates are not a single price”: any analysis that reduces “interest rates” to “the policy rate” has already become distorted at the very first layer defined in this entry.

See Also

• The Dual Anchors of Interest Rates and Exchange Rates: A Macro Observation Framework for the Age of High Volatility
• The Interest Rate as Macro Anchor: A Seven-Layer Decomposition
• A Century of Central Bank Crisis Response: Four Stages of Policy Evolution and the Linear-Analogy Trap
• Foreign Exchange as the Second Macro Anchor: The Mundell Trilemma and Managed Floating

Source

Compiled draft z-0203 · included July 2026; included without attribution).