I'm not quite sure what to make of this either. I did notice the same thing myself today and thought, "how strange." Steem itself was down about 12% on CMC, while SBD were up substantially. I still don't understand the difference between "STEEM," and SBD. All i know is i'm hodling SP while the others can be traded. After noticing this I'm not sure what to do w/them!! I was gonna post on this too but you beat me to it ><. Thank you for informing myself and the community!!