China has unveiled sweeping regulations governing overseas share sales by the country’s firms, taking one of its biggest steps to tighten scrutiny on international debuts in the wake of Didi Global Inc.’s controversial listing.

The regulations, issued by the country’s securities watchdog, commerce ministry and top economic planning agency over the past week, cast more uncertainty over the prospects for overseas initial public offerings that had proceeded virtually unchecked for two decades. The Nasdaq Golden Dragon China Index dropped 1.1% overnight despite another all-time high for U.S. shares, while the Hang Seng Tech Index slipped as much as 1% in early trading Tuesday.

Chinese firms in industries banned from foreign investment will need to seek a waiver from a negative list before proceeding for share sales, the National Development and Reform Commission and the Ministry of Commerce said in a statement on Monday. Overseas investors in such companies would be forbidden from participating in management and their total ownership would be capped at 30%, with a single investor holding no more than 10%, according to the updated list effective Jan. 1.