Regencell Bioscience Holdings Ltd., a tiny Hong Kong-based traditional Chinese medicine company listed on Nasdaq, saw its share price rocket 82,000% in mid-June, briefly lifting its market value above US$33 billion. The rally propelled founder and chief executive Yat-Gai Au, who controls about 86% of the stock, into the ranks of the world’s 100 richest people—at least on paper. The gains evaporated almost as quickly as they appeared. By 26 June the shares had tumbled 74%, and they traded at US$12.34 on 2 July, down from a peak of US$83.60 but still roughly 9,400% higher for the year. The company, which has reported cumulative losses of more than US$10 million over the past two fiscal years, blamed short sellers for the extreme volatility in a statement on 1 July. Regencell’s sudden ascent and collapse have drawn the attention of market observers and, according to analysts, are likely to be reviewed by the U.S. Securities and Exchange Commission and the Financial Industry Regulatory Authority, which routinely screen for potential pump-and-dump activity in thinly traded stocks. The firm has not responded to requests for comment. Founded in 2014, Regencell licenses and markets herbal formulas developed by Au’s father to treat attention-deficit hyperactivity disorder and autism spectrum disorder. Despite its minimal revenues and vacant chief medical officer post, the company has cultivated a large social-media following by promotions such as concert-ticket giveaways. Whether that following can translate into sustainable investor confidence now that the share price has crashed remains unclear.