SBD is not getting printed now because of a built-in safety net feature in the steem blockchain. So if the debt ratio (total SBD in existence / total Steem market cap) goes above 2% author rewards will paid only in Steem and Steem Power. We are currently past 5% debt ratio and that is why SBD is not getting printed any more.
So that makes the availability of SBD limited, to help it resist the market movements. However, steem is getting traded in exchanges and is directly controlled by the price movement of the BTC market. So its getting affected.
Hope this answers to your question ?