$USDC usdc's annual interest rate for the first 500u has risen to 11%, while usdt's annual interest rate has dropped to 2%, and usdc contract trading is fee-free. Contract fees are expensive, with limit orders costing 0.02% of the position, and market orders costing 0.05% of the position. For a large position (currently 80K), the market order fee is 40u, and opening and closing the order costs 80U in total. Your referrer earns 30% from you, which is 24U, regardless of whether your order is profitable or not; they will still receive 24U. (The maximum can reach 40%, earning 32u).