The retail portion of a 576 million US dollars share offer by Air China was oversubscribed, the Reuters reported. But analysts said retail demand may have been inflated by big institutions' efforts to ensure the initial public offer's success, and they were not optimistic about the stock's short-term performance after it listed in Shanghai. The retail oversubscription rate was the lowest among a dozen IPOs since regulators lifted a year-long ban on new stock offers in May, official media said. Some analysts said big institutions may have taken steps behind the scenes to drum up retail orders, exaggerating the actual strength of retail interest.