Yes, the reason for that is that the internal market is priced in terms of SBD. How much steem you can get per one SBD. Since SBD is way up right now ($1.64 last check) Steem is trading a proportional discount. Any time SBD is trading at a premium, Steem will be at a discount. Any time SBD is at a discount Steem will be trading at a premium. Does that make sense at all?

Basically if SBD is 50% higher, Steem will be 50% lower... on the internal exchange.