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.