Instead of relying on manual adjustments by administrators to balance supply and demand, Aspan uses an algorithmic fee curve to guide market behavior. This is the core of the protocol’s self-regulation.
The system real-time monitors the Collateral Ratio (CR) and adjusts Mint and Redeem fees accordingly.
Fee Logic Matrix
System Status
CR
xBNB Leverage
Target
Mint xBNB
Redeem xBNB
Mint apUSD
Redeem apUSD
🟢 Zone A：Low Leverage
> 170%
< 2.5x
Decrease CR
Base Fee
2%
Base Fee
0%
Base Fee
0%
Base Fee
1%
🔵 Zone B：Healthy Mode
(Target Range)
150% - 170%
2.5x - 3.0x
Maintain the quo
Base Fee
1%
Base Fee
1%
Base Fee
0.1%
Base Fee
0.3%
🟠 Zone C：Stable Mode 1
(Risk Alert)
130% - 150%
>3.0x
Increase CR
Base Fee
0.5%
Base Fee
4%
Base Fee
0.5%
Base Fee
0.1%
🔴 Zone D：Stable Mode 2
(Rebalance)
< 130%
>4.3x
Forced Deleveraging
Base Fee
0%
Base Fee
8%
Suspended
Base Fee
0%
How Arbitrageurs Work
When the system enters an unhealthy state (e.g., CR < 140%), the protocol activates a "discount promotion" mode.
Example: The xBNB minting fee may be set to -1.0% (i.e., a 1% reward).
Arbitrage Behavior: Trading bots will realize that minting xBNB on Aspan is cheaper than buying BNB on Binance. They will flood in to mint xBNB (and hedge on CEXs), injecting a large amount of collateral into the protocol and pulling CR back to 150%.