Interest rate changes directly affect your "interest income on reserve funds" — and the effect is more direct than you might think.
When a company holds stablecoins in advance for payments, it is essentially swapping "cash" for "interest-bearing cash equivalents." USDC's reserves are mostly invested in short-term U.S. Treasuries and overnight reverse repurchase agreements. The yields on these assets move with the federal funds rate. The USDC you hold does not earn interest itself (the GENIUS Act prohibits stablecoins from paying interest), but the issuer (Circle) earns interest on the reserves and passes the effects of rate changes through the whole ecosystem through market mechanisms.
How Interest Rate Changes Affect Your Reserve Costs
Let's break it down: the "cost" of holding USDC as reserves has two parts.
1. Opportunity cost: the higher the interest rate, the more you lose by holding USDC
If you have cash that could earn 4–5% per year in a bank deposit or short-term U.S. Treasury bills, and USDC pays no interest, then holding USDC means giving up that interest income. Circle's reserve income comes from interest on the U.S. Treasury bills backing USDC, but most of the yield is taken by distribution partners, and users receive none of it.
Every time the U.S. benchmark interest rate drops by 25 basis points, Circle's annual income directly falls by about $40–60 million. But for companies, a rate cut also means the opportunity cost of holding USDC falls — because cash in the bank no longer earns as much either.
2. Exchange rate movement: stablecoins are "stable" in U.S. dollars, not in your local currency
The basic rule of who bears exchange rate losses has not changed: whoever bears exchange rate risk depends on what the contract says. But interest rate changes can affect exchange rates themselves — Fed rate cuts usually weaken the U.S. dollar, so your USDC may be worth less when converted back into your local currency.
Practical Steps: Three Things to Do When Rates Change
First, check how long your reserve period is. If you hold USDC for more than 30 days before paying it out, the effect of interest rate changes on opportunity cost cannot be ignored. Circle's reserve yield fell from 4.16% to 3.5% in less than a year — faster than you might expect.
Second, consider putting reserve funds somewhere that earns yield instead of holding idle USDC. Some DeFi protocols offer yield on USDC deposits, with annual rates around 3–4%. But note: this is not risk-free. Protocol risk and smart contract risk still exist. If you want certainty, it may be better to hold short-term U.S. Treasury bills or money market funds, and convert to USDC only when you need to make a payment.
Third, watch what happens after the GENIUS Act. After the Act passes, stablecoin issuers gain a clear federal regulatory framework. Circle, Paxos, and others have received conditional bank charters, but this has not changed the rule that stablecoins themselves cannot pay interest. If regulators later relax the interest restriction, the yield characteristics of holding stablecoins could be redefined. That stage has not arrived yet.
Final Check
Open your stablecoin wallet or exchange account and find a USDC balance you have held for more than 30 days. Calculate how much interest you could have earned by putting that money in short-term U.S. Treasury bills (currently around 3.5–4% per year) during those 30 days, then compare it with what you actually earned (usually zero). That gap is where interest rate changes really affect your reserve costs.
Verification channel: Check the "reserve yield" line in Circle's public financial reports. This is the "market reference rate" for holding USDC as reserves. If it is lower than the risk-free rate in your own country, then the cost of holding USDC as reserves is positive — every day you hold it, you lose one day of interest.
