Just days before it shares were due to start trading, Ma and top aunt executives were summoned by financial regulators for a chat.

That very same day, new rules targeting ants lucrative and fast growing online lending business were unveiled.

Shanghai and Hong Kong Stock Exchange is then suspended the AIPO, citing disclosure requirements.

It's a huge and dramatic setback for Mama and aunt.

The company would have been valued at over $300 billion.

And worryingly, the intervention underscores a much tougher approach towards China's Fintech pioneers.

Just last month, Ma had criticized financial regulators of stifling innovation, and Beijing is responding with new rules that would treat aunt and its peers more like banks rather than technology companies.

The share sale will probably still continue at some point, but it could also shrink, depending on the impact of the new rules on ants business models.