https://coinmarketcap.com/currencies/steem-dollars/#markets
Coinmarketcap currently shows incorrect Steem Dollar prices of $13.36 for the internal STEEM/SBD exchange.
Most likely the bug is because of swapped rates, the current rate is 3.5 SBD per STEEM not 3.5 STEEM per SBD.
I have sent them a message informing of this, so hopefully it'll get fixed soon.