Why the APY shown in DeFi is not what you will actually earn
The displayed APY on a DeFi dashboard is a number produced by a machine. It is not a promise. It is not a guarantee. It is a snapshot of one moment in a system that changes constantly.
Many retail users see 40% APY and think they will get 40% more tokens after one year. That is almost never what happens. The gap between displayed APY and real return can be enormous; sometimes it is negative.
The components the dashboard does not show
A liquidity mining position involves several forces working against each other. The display APY usually only reflects the current rate of farming token emissions. It ignores the following.
Token price depreciation. The rewards you earn are paid in the protocol's own token. That token often declines in value as early farmers sell. The high APY attracts depositors. Those depositors then become sellers. By the time your rewards are claimable, the token may be worth 60% less than when the APY was shown.
Impermanent loss. When you provide liquidity to a volatile pair, the ratio of the two assets shifts as prices change. This loss is real. It is deducted from your principal. The displayed APY does not account for it. A 40% APY can be irrelevant if your principal shrank by 30% from impermanent loss alone.
Gas costs. On Ethereum mainnet, each deposit, harvest, and withdrawal costs gas. If you are a small depositor, these fees can consume all your rewards. A $50 gas fee on a $500 position is a 10% headwind before anything else happens.
Protocol fees. Some pools charge entry fees, exit fees, or performance fees. These are sometimes buried in the smart contract and not shown on the front end.
Emission rate decay. Many programs start with high emissions that drop over weeks. The dashboard often shows the current rate. By week four, the actual emission may be half of what you saw on day one.
Vesting schedules. Some rewards do not come immediately. They vest linearly over months. If the token price falls during that vesting period, you receive fewer dollars worth of tokens. The displayed APY assumes instant value.
A real example using plausible numbers
Consider a liquidity mining position on a volatile pair. The dashboard shows 40% APY. You deposit $10,000. After 90 days you decide to withdraw.
The token you earn has dropped 50% in value during those 90 days. Your nominal reward count is roughly 1/4 of the annual rate. That gives you about $1,000 in tokens at their current price. But those tokens were worth $2,000 when emitted.
Impermanent loss on a volatile pair over 90 days with a 20% price swing in one asset runs roughly 2% to 5% of principal. Call it $300.
Gas for three harvests and one withdrawal: $200 on a medium-traffic block.
Your final position: $10,000 principal minus $300 impermanent loss, minus $200 gas, plus $1,000 in depreciated reward tokens. That is $10,500. A 5% nominal gain over 90 days.
The displayed APY suggested a 40% annual return. What you actually got was roughly 5% for three months. Annualized, that is about 20%. But that does not include the time cost or the price risk of holding the reward token for another six months while it vests.
You may well end up negative after vesting.
A reference: Lido stETH displayed APR versus actual
Liquid staking tokens like stETH show an APR when you deposit ether. That APR reflects the current issuance rate from the Ethereum consensus layer. But the APR you actually receive depends on the price of stETH relative to ETH on the secondary market.
In periods of market stress, stETH has traded at a discount to ETH. If you bought stETH at a discount and later redeemed for ETH at parity, your actual return exceeded the displayed APR. If you bought at a premium and later redeemed at a discount, your actual return was below the displayed APR.
The same principle applies everywhere. The displayed number is a model input. The realized number is a function of market conditions, your timing, and the actions of everyone else in the pool.
What you can do
Treat displayed APY as a starting point, not a conclusion. Compare the emission rate to the historical price action of the reward token. Check whether rewards are vested. Estimate your likely impermanent loss. Add up the gas cost of your planned interaction frequency.
If the position looks marginal on paper, it will almost certainly be worse in practice. The number on the dashboard exists because someone wants your capital in the pool. It is not there to help you.
Not financial advice. brooder.tech publishes market data and general information about digital assets. Crypto assets are volatile and you can lose everything you put in. Nothing here is a recommendation to buy, sell or hold, and we make no price predictions.
Prices are sourced from third parties and may be delayed or wrong. Verify anything you intend to act on against a primary source.