All Synthetix currency positions (sUSD, sEUR, sJPY, etc.) are combined and mirrored into a single position of USDC. Currently, the pool holds WETH for sETH, WBTC for sBTC and LINK for sLINK. Positions with less than 1% weights are not considered. dUSD is a stable coin yield pool. The dUSD token will appreciate in price via LP fees and harvesting the rewards (ATM BAL). The performance mining rewards are extra on top of that which currently include DHT, MATIC, and 1inch.