High P/S ratio may pose a risk if the company underperforms the industry. Declining revenue and underperformance against industry's 25% forecasted expansion could lead to share price drop. Investors risk overpaying if recent medium-term revenue trends persist.

Nanfang Ventilator's high P/S ratio may be due to investors' high expectations. However, its recent negative growth rates and shrinking revenue over the medium-term, coupled with the industry's growth forecast, make the high P/S uncomfortable.