Hong Kong-listed automobile stocks continued their downward trend on September 10, with shares of NIO falling nearly 5% and XPeng declining close to 4%. Meanwhile, Voyah Automobile dropped over 3%, while Geely Automobile, BYD Company Limited, and Great Wall Motor Company Limited all shed more than 2%.

The selling pressure came as market participants digested a major regulatory development from September 7, when the government issued the "Notice on Promoting Automobile Enterprises to Standardize Supplier Payment Terms and Optimize Payment Period Management." This marks the first national-level document targeting payment-cycle management specifically for a single industry. The core of this policy upgrade shifts the 60-day payment period governance from corporate commitments and industry initiatives to a formal regulatory standard at the national department level, while also closing loopholes that could allow companies to circumvent the new requirements.

Adding to the sector's woes, fresh data from the China Passenger Car Association revealed that retail sales of new energy passenger vehicles reached 1.005 million units in August, reflecting a year-on-year decline of 10.1% but a month-on-month increase of 5.7%. For the January-to-August period, NEV retail sales totaled 6.674 million units, down 12.1% compared with the same period last year.

These combined factors—the new payment-cycle regulation and softer NEV sales figures—have intensified investor concerns about the near-term outlook for the sector, resulting in broad-based selling across Hong Kong-listed auto stocks.