lately they do have ZrCoin too which isn't released yet. are they doing IOU for this SONM? after zrcoin was listed to hitbtc, the zrcoin team announced that the zrcoin on hitbtc were fake. this SONM from hitbtc must also be fake.
It is possible they're selling something they don't own yet, like a futures contract.
it's far more likely that they're buying/selling their OWN ious to make it seem like it's occurring, thus getting a few noobs to lose money.
There's absolutely no way it's a consistent thing when they're 0/100 in terms of how high the price goes when it hits exchanges...