Where This Lesson Fits
Previous lessons examined how asset-side products such as loans and investments respond to interest rate changes and how duration mismatch creates balance sheet sensitivity.
This lesson focuses on the liability side of the balance sheet — particularly deposits and other funding sources.
Understanding how funding costs respond to interest rate changes is essential because liability repricing directly affects a bank’s net interest margin.
Lesson Objective
By the end of this lesson, students should be able to explain how deposit pricing behavior and funding structure influence liability-side interest rate sensitivity in banks.
Lesson Overview
Banks fund their assets primarily through customer deposits, along with wholesale funding sources such as interbank borrowing, repurchase agreements, or bond issuance.
Each of these funding sources responds differently to changes in interest rates. Some funding costs adjust quickly, while others adjust slowly or only partially.
Because of this variation, the liability side of the balance sheet can significantly influence how interest rate changes affect overall bank profitability.
Deposit Pricing Behavior
Deposit accounts are often slower to adjust to changes in market interest rates than many other financial instruments.
Banks may choose how quickly to increase deposit rates when market interest rates rise. Competition, customer expectations, and strategic funding goals all influence these decisions.
As a result, deposit interest rates often move gradually rather than immediately matching market rate changes.
Deposit Rate Sensitivity
Deposit rate sensitivity refers to how strongly deposit interest rates respond to changes in market interest rates.
Some deposits are highly sensitive to rate changes. For example, large corporate deposits or brokered deposits may move quickly toward higher-yield alternatives.
Other deposits are less sensitive because customers value convenience, relationships, or payment services more than interest income.
These behavioral differences create variation in how funding costs respond to changing market conditions.
Deposit Betas
Banks often measure deposit sensitivity using a concept known as the deposit beta.
Deposit beta describes how much deposit rates change relative to a change in market interest rates.
For example, if market rates rise by one percentage point but the bank increases deposit rates by only half a percentage point, the deposit beta would be 0.5.
This measurement helps asset–liability managers estimate how funding costs may evolve when interest rates move.
Funding Mix and Cost Stability
The mix of funding sources also affects liability-side interest rate risk.
Banks with a large share of stable retail deposits may experience slower funding cost increases when rates rise.
Institutions that rely more heavily on wholesale funding or rate-sensitive deposits may see funding costs adjust much more quickly.
Because of these differences, funding structure plays a key role in determining interest margin stability.
Customer Behavior and Deposit Stability
Deposit behavior is influenced not only by interest rates but also by customer preferences and financial relationships.
Some depositors maintain long-term relationships with their bank and may not move funds immediately when market conditions change.
Other customers actively seek higher yields and may transfer funds to competing institutions or investment products when rates rise.
These behavioral patterns make deposit funding both a financial and behavioral component of asset–liability management.
Margin Impact of Funding Repricing
When interest rates rise, banks may face pressure to increase deposit rates in order to retain funding.
If funding costs rise faster than asset yields, net interest income can decline.
When rates fall, the opposite may occur: deposit costs may decline slowly, while asset yields adjust downward more quickly.
Understanding these dynamics helps asset–liability managers anticipate margin pressure under different rate environments.
Why Liability Behavior Matters
Interest rate risk is often discussed in terms of asset repricing, but liability behavior can be just as important.
If deposit costs rise rapidly while asset yields remain fixed, earnings pressure can emerge even when asset volumes remain stable.
For this reason, asset–liability management must evaluate both sides of the balance sheet together.
What Good Basic Interpretation Looks Like
Students should understand that deposit pricing and funding mix significantly influence a bank’s exposure to changing interest rates.
Asset–liability management therefore analyzes not only assets and investments but also the behavioral characteristics of deposit funding.
Common Misunderstandings
Thinking deposits always reprice immediately
Deposit rates often adjust gradually because of competitive strategy and customer behavior.
Assuming all deposits behave the same way
Different deposit categories have different levels of rate sensitivity and stability.
Believing interest rate risk exists only on the asset side
Liability repricing behavior can significantly influence earnings and margin stability.
Practical Exercises
Exercise 1
Explain how deposit betas help banks estimate funding cost changes when interest rates rise.
Exercise 2
Describe how reliance on wholesale funding could increase liability-side interest rate sensitivity.
Exercise 3
Discuss why customer behavior affects the stability and cost of deposit funding.
Key Terms
Deposit Repricing — The adjustment of deposit interest rates in response to market rate changes.
Funding Sensitivity — The degree to which funding costs change when market interest rates move.
Deposit Beta — A measure of how much deposit rates change relative to market interest rate changes.
Funding Mix — The combination of deposit types and borrowing sources used to fund bank assets.
Wholesale Funding — Large-scale borrowing from financial markets or institutional counterparties.
Knowledge Check
Question 1
What does deposit beta measure?
A. The number of deposit accounts in a bank
B. The sensitivity of deposit rates to changes in market interest rates
C. The physical size of bank vaults
D. The number of loans issued
Question 2
Why might deposit rates rise slowly when market rates increase?
A. Because deposit pricing often reflects competitive strategy and customer behavior
B. Because banks cannot change deposit rates
C. Because deposits never earn interest
D. Because market rates do not affect funding
Question 3
How can funding mix affect interest rate exposure?
A. Different funding sources respond differently to rate changes
B. Funding mix has no impact on risk
C. Deposits eliminate interest rate risk
D. Funding structure only affects accounting reports
Lesson Summary
- Deposits are the primary funding source for most banks.
- Deposit interest rates often adjust more slowly than market rates.
- Deposit betas measure how sensitive deposit pricing is to rate changes.
- Funding mix influences how quickly liability costs respond to interest rate movements.
- Understanding deposit behavior is essential for managing net interest margin stability.
Next Lesson Preview
The next lesson examines how banks evaluate the effect of interest rate changes on net interest income and economic value across the balance sheet.
Continue to Lesson 36.5