The economic system is designed in such a way that the value of SBD should be close to a dollar. There are two main mechanics that are designed to help "peg" the SBD to the dollar. Those are the "convert" function available through the wallet, and the interest rate that SBD balances earn. Both have their flaws, but seem to be working enough that right now 1 SBD is worth about $0.95... Though I think mostly that's through the power of suggestion, I'm content to leave well enough alone.