Regencell Bioscience shares sank 15.6% in premarket trading on Friday.

Regencell Bioscience Holdings, an early-stage, Hong Kong-based bioscience company with no revenue, is the latest speculative overseas stock to attract an unusual surge in trading demand.

Shares of Regencell, which says it develops traditional Chinese herb treatments to treat childhood attention deficit hyperactivity disorder and autism, more than tripled on Monday — soaring more than 280% by the close after a 38-for-1 split declared on June 2 took effect. By Monday’s close, Regencell, founded in 2014 and traded on Nasdaq under the ticker ‘RGC’ since 2021, had a total market capitalization of $29.7 billion, according to S&P Capital IQ.

The stock continued to jump on Tuesday, gaining 30%. The company’s year to date performance is off the charts too, having risen 59,900% in 2025. Its current market value of $36 billion tops Lululemon, eBay and Kraft Heinz. The shares traded for pennies at one point in the past one year.

The stock pulled back 18.8% on Wednesday, as speculative fervor cooled.

Regencell is the latest example of a speculative international stock attracting attention during summer trading. In August, 2022, for example, AMTD Digital, a Hong Kong-based fintech company, climbed 126%, briefly giving it a market value greater than Coca-Cola and Bank of America.

Earlier this month, Regencell explained the stock split as designed solely “to enhance liquidity in the market for the company’s ordinary shares and make the shares more accessible to investors.” Stock splits do not change anything fundamentally about a company.

Regencell's surge also came amid an increased focus on alternative medicines after Robert F. Kennedy Jr. was sworn in as Secretary of the U.S. Department of Health and Human Services in February. Kennedy, a vaccine skeptic, has taken steps to discourage routine immunizations in the U.S., last week removing all of the members of a panel that advises the Centers for Disease Control and Prevention on vaccines.

Regencell's stock often makes huge one-day swings. For example, shares jumped roughly 30% on March 21, before dropping 30% the following trading day.