How is the Net APY calculated for Pendle PT positions?

The Net APY shown on DeFi Saver factors in the currently available APY for the specific PT on Pendle.

However, the APY on PTs changes from day to day, so the one that's relevant for your Aave position is the currently available PT APY, seeing as that's the "locked" APY for your PT.

How it works:

On August 22, 2025 - the APY on PT sUSDe September is 11.4%:

This same amount is shown as the APY on DeFi Saver:

However, this APY only applies if the PT was minted at this moment.

For example, the APY on PT sUSDe September on August 19, 2025 at 4 PM was 11.16%

If someone opened a PT position while they had this APY locked, that's the APY their PT will be earning, even though DeFi Saver's market section might show a different APY.

Now, let's look at thow the Net APY is calculated on DeFi Saver:

To understand how we reach the 65.07%, let's break down what each value represents:

• The annual [token] interest represents the yield value on your PT, so in this case: $14,661,765 * 0.114 = $1,671,441.21 (the $1.67M from the screenshot)

• .The Base annual interest is the difference between your annual supply value and your annual borrow value. Since Pendle PTs have no supply APY on Aave, and this position has USDT and USDC as debt - we get: ($14,661,765 * 0%) - (($6,430,529.6 * 6.517%) + ($6,983,721 * 6.299%)) = -$858,869

• The total annual interest is then calculated as: Annual [token] interest + Base annual interest: $1,671,441.21 + (-$858,869) = $812,572.21

Please keep in mind that the numbers don't match 100% since DeFi Saver calculates the values with 10+ decimals, while we're rounding them up to 2 or 3 in this example to ensure visual clarity.

• From there, the Net APY % is calculated as: (Total annual interest / (supply balance - debt balance) ) * 100 ($813,271 / ($14,661,765 - $13,414,250.61) ) * 100 = 65.19%

With this in mind, you can get a better idea of how the Net APY shown on DeFi Saver might be a discrepancy between the Net APY your position will have - as the calculation heavily relies on the APY your PT had at minting.

As such, you can use the calculation from above, and instead of the APY on DeFi Saver, input the APY your PT had at minting, and you'll get a very precise Net APY for your position.

From a technical point of view, it would be extremely difficult and demanding to fetch and track the APY that was available at the time the PT was acquired, which is why we opted to use the current PT APY from Pendle for Net APY calculations.

We're aiming to improve these calculations and will look to offer precise calculations in the coming months.