SBD's will almost always fluctuate between +/- 10% of 1 USD worth of Steem.
However, given the thin supply we will always see large spikes in such a volatile market as cryptos. Holding SBD is not as attractive as holding steempower in my opinion, but you could certainly earn them here and try and get the best price for them when you can.
RE: Steem Dollars/US Dollar (SBD/USD) Price Charts for Nov 29th 2017 - 24h Change - 17.384%