Similar to OHM, each SDA is backed by 1 DAI, not pegged to it. Because the treasury backs every SDA with at least 1 DAI, the protocol would buy back and burn SDA in the event it trades below 1 DAI. This has the effect of pushing SDA price back up to 1 DAI. SDA could always trade above 1 DAI because there is no upper limit imposed by the protocol. Think pegged == 1, while backed >= 1. Intrinsic value of SDA is 1 DAI based on the contract. In reality, it becomes 1 DAI + premium as the treasury grows in assets.