(Yicai) May 12 -- The share price of Beigene and several other pharmaceutical firms that have drugs approved for sale in the US took a knock today after US President Donald Trump announced plans to drastically cut prescription drug prices in the United States.

Beigene’s share price [SHA: 688235] closed down 9 percent at CNY221.50 (USD30.71), while its Hong Kong-listed shares [HKG: 6160] slumped 9 percent to end the day at HKD127.80 (USD16.40).

Other pharma firms were also affected. Hutchmed [HKG: 0013], which is controlled by conglomerate CK Hutchison Holdings, slumped 3.6 percent to finish the day at HKD21.70 (USD2.80). Meanwhile, Henlius Biotech [HKG: 2696], a subsidiary of pharmaceutical giant Fosun Pharmaceutical Group, sank 2.8 percent to HKD34.25 (USD4.40).

The selloff was triggered after Trump announced his latest bold move on social media platform Truth Social yesterday.

"I will be signing one of the most consequential executive orders in our country’s history. Prescription drug and pharmaceutical prices will be reduced, almost immediately, by 30 percent to 80 percent," Trump said.

"I will be instituting a most favored nation's policy whereby the US will pay the same price as the nation that pays the lowest price anywhere in the world," he added.

The US is the world’s biggest market for innovative drugs, and companies are able to set their own prices under its free-market approach and strong patent protections. This has made the US a key source of revenue for many multinational pharmaceutical firms.

Beigene, for example, has two cancer drugs for sale in the US, namely the BTK inhibitor Brukinsa (Zanubrutinib) and the PD-1 therapy Tevimbra (Tislelizumab). In the first quarter, Zanubrutinib's sales in the US surged 62 percent from the same period last year to CNY4 billion (USD553 million), accounting for half of the firm's revenue that quarter, according to its earnings report released on May 8.

Thanks to robust global sales of Zanubrutinib, Beigene turned an operating profit for the first time in the first three months, raking in CNY151 million (USD20.9 million) compared to losses of CNY1.8 billion (USD249.2 million) a year ago. However, the company still posted a net loss attributable to shareholders of CNY94.5 million (USD13.1 million).

Editors: Dou Shicong, Kim Taylor