they runaway ! Please be careful don't hold your assets at exchange wallets,
sometime they say we got hacked or simply run away,
Lesson learned for me, cause I was too confident about exchanges like IDAX that they will not run away since they already have a reputation but I guess it is really hard since you are not holding any private key on it! IDAX was really good I am using it for less than a year but now I am totally rekt.