What is Implied APY?
Implied APY is the annualized yield rate that the market collectively expects for a yield-bearing asset, as derived from the current trading prices of yield-stripped tokens. When principal and yield tokens trade on secondary markets, their prices encode the market's expectations of future yields. Calculating implied APY from these prices reveals what traders collectively believe the underlying asset will earn.
This concept is similar to implied volatility in options markets. Just as option prices reveal expected volatility, yield token prices reveal expected yields. Implied APY provides a powerful tool for comparing market expectations against your own analysis and identifying potential opportunities.
How it Works
Implied APY can be calculated from principal token prices using the discount from par. If PT-stETH trades at 0.96 with exactly 1 year to maturity, the implied APY is approximately 4.17% (1/0.96 - 1). For shorter maturities, the calculation must annualize: a 6-month PT trading at 0.98 implies approximately 4.08% APY ((1/0.98)^2 - 1).
Yield token prices also imply yields. If YT-stETH representing 1 year of yield trades at 0.05 stETH, the implied APY is 5%. The YT buyer expects to receive approximately 0.05 stETH in yield distributions over the year.
In efficient markets, PT-implied and YT-implied yields should approximately match. The underlying asset value equals PT + YT, so: underlying = PT + YT, and (underlying - PT) / underlying = YT / underlying = expected yield percentage.
Implied APY changes constantly as PT and YT prices move. During periods of high yield expectations, PTs trade at deeper discounts, and YTs are more expensive. When expectations fall, PTs approach par, and YTs cheapen.
Comparing implied APY to current variable yields identifies market sentiment. If stETH currently yields 4% but implied APY shows 5%, the market expects yields to increase. If implied is lower than current, expectations are for yield decline.
Practical Example
You're analyzing PT-stETH with 6-month maturity trading at 0.975 stETH. The implied APY calculation: (1/0.975)^2 - 1 = 5.19% annualized. Current stETH variable yield is 3.8%. The market is pricing in yield increases over the next 6 months. You believe yields will actually fall to 3%, so you sell YTs (expressing a bearish yield view) and buy PTs (locking in the 5.19% fixed rate that exceeds your expected 3% variable yield).
Why it Matters
Implied APY is the market's collective wisdom about future yields. It enables comparison shopping between fixed and variable strategies, identification of mispriced opportunities, and informed speculation on yield direction. Sophisticated yield farmers use implied APY to inform all their rate-related decisions. Understanding this concept elevates your yield strategy from passive participation to active rate management. Fensory calculates and displays implied APY across all yield-stripped positions, making it easy to compare market expectations with current rates and your own analysis.