How did Bitstamp replenish the 19k coins they lost so quickly?

So Bitstamp has the cash reserve or BTC to replenish those 19k coins that they lost. But how?

A little bit of assumption here, I do not think bitstamp or any exchange holds assets of BTC in large quantities. Definitely not 13% of total bitstamp coins.

Therefore, it is reasonable to say that bitstamp has to come up with the coins some how and QUICK. 

Bitstamp won't trade on Chinese exchanges and definitely not Bit-E. Bitfinex is their only choice.

Look at the abnormal volume profile of large market buy orders at exactly 18:30 UTC yesterday and the day before. It is clear this is a large buy order and not short covering (bitfinex short swaps didn't' go down) In addition, the total sum of volumes for green bars during this period comes out to be about 13k.

Shortly after those movement, bitstamp is open the very next day. Just connecting the dots here, even imaginary ones.