The spread between a savings account rate and a credit card APR feels like a penalty. It is actually a product feature.
Banks operate on a model called net interest margin. They buy money from depositors and sell money to borrowers. The price difference is the profit. The reason the price paid to depositors varies wildly between institutions is not regulation, but funding strategy.
The mechanism
A bank needs money to lend. This capital comes from two primary sources: customer deposits and wholesale funding. Wholesale funding includes borrowing from other banks, issuing bonds, or accessing the Federal Reserve’s discount window.
Large institutions like Chase or Bank of America have massive branch networks and established relationships on Wall Street. They can access wholesale capital at rates tied to the Federal Reserve’s benchmark rate. Because they have these alternative sources, they do not need to compete aggressively for deposits. A savings account at a large bank is a convenience product, not a primary funding source. They can afford to pay 0.01% because they can borrow more cheaply elsewhere.
Online banks like Ally Bank or Marcus operate differently. They lack the physical infrastructure and the scale of wholesale access to borrow cheaply. Deposits are their primary, and often only, funding source. To grow, they must compete for the same depositors the big banks ignore. They pay 4% or more because they have to bid for that capital directly.
The credit card loan is the same product regardless of the issuer. The risk of lending to a consumer is high, so the interest rate charged is high. The Federal Reserve sets the baseline cost of money for the economy, but the final APR is determined by the bank’s cost of funds plus a risk premium. A standard variable APR sits around 22.99%. This rate applies whether the bank is a massive conglomerate or a digital-only lender.
The math
The difference in funding strategy creates a tangible gap in returns for the depositor. The cost of capital for a large bank is lower due to wholesale access, allowing them to maintain a wider margin on loans while paying depositors almost nothing. An online bank must pass more of that yield to the depositor to secure the funds in the first place.
Consider a $10,000 balance held for one year.
| Institution Type | Example | Savings APY | Interest Earned on $10k | Funding Strategy |
|---|---|---|---|---|
| Large Bank | Chase | 0.01% | $1.00 | Wholesale + Deposits |
| Online Bank | Ally | 4.50% | $450.00 | Deposits Only |
The difference is $449 in lost income per year on a single account. This is not a fee. It is the bank retaining the spread between what they earn on loans and what they pay for deposits.
Credit card APRs are generally uniform across institutions for similar risk profiles. A cardholder with good credit might see 22.99% at Chase. The same borrower would see a similar rate at a smaller issuer. The bank does not charge more on the loan side to offset the low deposit rate. The loan rate is determined by the market risk of the borrower, not the bank’s cost of deposits. The bank simply pockets the difference.
When the rule of thumb breaks
The gap between savings rates does not stay static. It widens and narrows based on the Federal Reserve’s monetary policy. When the Fed raises interest rates to combat inflation, the cost of borrowing increases across the board.
Big banks are slower to pass these rate hikes to depositors. Because they are not desperate for liquidity, they keep savings rates near 0.01% even when the Fed Funds Rate is 5%. They protect their net interest margin by keeping funding costs low. Online banks are faster to adjust. They need volume immediately, so they raise savings APYs quickly when the Fed moves.
There is a risk factor to consider. Both the large bank and the online bank offer FDIC insurance up to $250,000. The FDIC guarantees the principal regardless of the institution’s funding strategy. The safety of the money is identical. The only variable is the return.
Deviation occurs when a bank offers a specific promotional rate. A large bank might offer 4% on a savings account for the first three months to acquire a new customer. This is a marketing cost, not a structural shift. Once the promotion ends, the rate reverts to 0.01%. This is distinct from the structural 4.50% offered by online banks, which is baked into their business model.
The summary
For most people, in most situations, the right move is:
- Keep emergency funds in an online bank paying 4.50%.
- Use large banks only for physical branches or specific loan products.
- Pay off credit card balances before interest accrues at 22.99%.
The FDIC insurance is the same, but the math is not. Leaving $10,000 in a large bank costs $449 a year compared to an online alternative. The spread is the product. The bank retains the margin on the loan side while paying you near-zero on the deposit side because they do not need your money to lend. Online banks need the money, so they pay for it. Move the savings where the bank needs the capital, not where you have a branch location.