MANILA – Tycoon Roberto Ongpin resigned on Thursday as chairman of online gambling company PhilWeb Corp., one day after President Rodrigo Duterte singled him out in a speech which included criticisms of the country’s oligarchs.

PhilWeb shares plunged by as much as 50 percent, before closing 36.88 percent lower to P8.95. It was the stock's steepest decline on record according to Bloomberg.

Ongpin, a trade minister during the Marcos dictatorship, announced his resignation as company chairman and director in a disclosure to the stock exchange. He did not give a reason for his decision.

Before his tirade on Wednesday, Duterte said in June that he would stop online gambling and since then, regulators have renewed the company’s license on a per-month basis.

“I think the last thing investors want is uncertainty or unpredictability of regulations,” BPI Asset Management chief investment officer Smith Chua told ANC’s “Market Edge with Cathy Yang.”

In a free-wheeling speech at the presidential palace on Wednesday, Duterte promised to “destroy” oligarchs whom he accused of making money at the expense of the poor.

“These are the guys na umuupo lang sa eroplano nila, umuupo lang sa mga mansion nila kung saan-saan yung pera nila nagpapatak, parang metro ng taxi. Sabi ko, destroy (These are the guys who sit in their private jets and their mansions, watching their money grow like a running taxi meter)” he said.

Adding to Ongpin’s woes is a P174-million insider trading fine imposed by the Securities and Exchange Commission over his 2009 purchase of Philex Mining shares. The businessman secured on Monday a 60-day restraining order from the Court of Appeals.