humourous sense(x)

The value of Indian Sensex is falling like anything.
I read this conversation somewhere on internet.
...
person A: What if the share values go negative?

(This seemed to be a rather ignorant than sarcasic question, going by the earlier conversation. The following witty reply made me laugh a lot.)

person B: Then you will get money for taking shares from market.
Just keep taking them and you will be richer than the CEO of Reliance!
..