buying SBD from the open market

Regardless of the source, when there is buy pressure what happens to the price? This is the mechanism that keeps the price near $1 (from below, at least): SBDs priced at <$1 are valuable, so people should want them (slight caveat: the haircut rule is also a factor). It is a distributed, decentralized mechanism. It doesn't work when the price is >$1 because there's no reason to do conversions. Doing conversions would take the SBDs out of circulation and the debt ratio would get better.