The Shanghai Stock Exchange has suspended Ant Group's potentially record-breaking IPO, it said in a statement, with Hong Kong authorities following suit shortly after. And a controversial speech from Jack Ma might have played a role in torpedoing the listing.

Alibaba's stock plunged on the news of the suspension. The eagerly anticipated listing was set to be the world's biggest IPO, raising almost $37 billion at a $313 billion valuation.

The news follows an announcement yesterday that Chinese regulators summoned Jack Ma and other senior executives to answer questions about the company's listing. In its statement, the SSE said that the questioning and related regulatory changes may cause Ant to fail to meet issuance requirements.

At the questioning, regulators reportedly told Ma that Ant would face increased scrutiny and be governed similarly to banks. While concerns over fintech regulation have circulated for years, the specific timing of this intervention is notable. The warning came just a week after Jack Ma publicly criticized the state of Chinese financial regulation, calling it too old-fashioned. Doing that in China, with its famously retaliative government, is always a risk. Doing it a couple of weeks before your company lists is a giant risk. And in this case, it may have backfired.

Others disagree on the timeline though: Chinese tech reporter Chen Du suggests that regulatory scrutiny increased as soon as Ant published its IPO prospectus. The increased scrutiny may have annoyed Ma, prompting his speech.

Either way, one thing is clear: something's gone very wrong with the IPO.