> For the complete documentation index, see [llms.txt](https://siriusprotocol.gitbook.io/whitepaper/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://siriusprotocol.gitbook.io/whitepaper/economy-and-security/what-is-apy.md).

# What is APY?

**APY** stands for **Annual Percentage Yield**. This measures the real rate of return on your principal tokens amount by taking into account the effect of compounding interest. In the case of Sirius Protocol, your <mark style="color:blue;">**$SIRIUS**</mark> tokens represent your principal, and the compound interest is added periodically on every Rebase event (every 15 minutes). &#x20;

Your new principal amount is your then current <mark style="color:blue;">**$SIRIUS**</mark> token amount, plus your new rebase token amount. This total amount is what gets calculated for your next rebase rewards.&#x20;

One interesting fact about **APY** is that your balance will grow not linearly but exponentially over time!

Our starting pool will have a **350,000% APY.**