Depositing into Ender Bonds

You may deposit ETH or stETH into bonds which are given as an NFT. You must set a bond maturity period from 7 to 365 days. Based on the maturity period, you are given a bond reward yield rate which is based on the period set. Currently, the minimum deposit amount is 0.1 ETH.

The bond yield rate is calculated based on the Base Rate, set at a fixed-rate that is based on the current asset yield rate of the LST deposited. Based on the rate, the maturity period will give a negative or positive bonus multiplier with longer periods having a higher bonus.

Period (days)	Yield Rate
7	-30%
15	-20%
30	-15%
60	-10%
90	Base Rate
120	+5%
150	+10%
180	+15%
220	+20%
260	+25%
280	+30%
320	+40%
360	+50%

This yield curve can be set/changed via governance vote which will impact all bonds retroactively.

Base Rate

The base rate for the bonds are set somewhere near or below the average yield rate of staking, acting as a baseline or "risk-free" rate for the bonds. Based on historical rates, we will set it appropriately to have a high-degree of certainty that the real staking yields will not fall below it by a substantial amount, with further padding being provided by the floating rate which is acquired through the strategy yields for a net yield basis. This may be changed on a year-over-year basis.

Using this chart as reference, we can see the rate has stabilized at around 3.3 - 3.5%, and so it would be appropriate to set the base rate for bonds to be 3% for the given year and at genesis.

Setting a Bond Fee

Users may set an optional self-set bond fee which takes a fee from the bond deposit upon the maturity of the bond and deducts that amount from the principal redemption of the bonds. This bond fee is now part of the treasury of the protocol, backing the protocol yield tokens.

By setting a bond fee, you are given a boost in various ways. For each % fee set, you are given a proportional multiplier to the bond yield above. For example, if you set a bond fee of 20%, you will get a 1.2x multiplier to your bond yield. In addition, you are also given a bonus in the governance token reward.

Users who hold a bond NFT with a bond fee set will also get a boost in the voting weight for their governance and governance token emissions voting. In addition, users who set a bond fee will get a multiplier on the Refraction Index increment.

Bond Reward

By depositing into the bonds, users are rewarded in a token, END, which are the protocol's yield token, that can be staked to give a concentrated yield. These are new type of liquid staking token, called a Concentrated Yield Token (CYT).

In addition, they also provide further utility in being able to be traded on the market as yield tokens, while also being able to be staked to get a rebase reward. Staked END tokens (sEND) can then be used to allocate liquidity of the bond deposited assets inside of the protocol's treasury to various strategies as well as liquid staking protocols for LSTs.

This makes it a unique yield token not only providing a concentrated yield, but acting as a token of universal Liquid Staking Power (LSP).