Devotees of entrepreneur Dai Wenjun’s famous duck neck snacks are so loyal that he could even sell them bricks cooked with his signature spices, he once boasted. But he can’t sell shares in his company to the public.

Hunan Juewei Food has been stuck for the past year in China's clogged pipeline of initial public offerings. About 675 companies are awaiting government approval to sell a total of roughly $63 billion in stock, according to a tally by The Wall Street Journal of securities filings.