This is jump is caused by HITBTC.

HitBTC is not really trading any SBD. It is all fake. Investors are winning and loosing big on it with real money, but the virtual supply of SBD on HitBTC is fake.

Her is why. HitBTC has abandoned the central STEEM/SBD wallet for 5 months (presumably forever). Within their exchange they have a virtual wallet system. Normally when you transfer STEEM or SBD in or out of the exchange, you would send it through a central wallet via a memo to keep track of who has what.

Since HitBTC has abandoned their STEEM/SBD wallet for so long, people who have transferred any STEEM/SBD into HitBTC have long since sold it for something else or just abandoned it.

You can go and look at the HitBTC STEEM/SBD wallet and you will find that nothing is happening to the balance.

So what are they trading?
Answer: It is fake money. Make believe. It is not real.
The only thing is real is investors are buying up this fake virtual money on HitBTC and trading it in high stakes gambling.

If HitBTC keeps up this system of fake currency trading on their exchange, people will eventually learn that HitBTC is not a real exchange and abandon it.

By the way, Poloniex is doing the same thing with STEEM and SBD.