Johnson & Johnson is in discussions to buy Protagonist Therapeutics, a source familiar with the matter told Reuters.
Shares of Protagonist surged more than 30% in afternoon trading. The company had a market capitalization of $4.2 billion as of Thursday’s close.
The two companies are working on the development of an oral treatment, icotrokinra, for immune diseases, including plaque psoriasis and ulcerative colitis, with J&J holding the exclusive rights to commercialize the product.
Protagonist declined to comment, and J&J did not immediately respond to Reuters’ requests for comment.
The Wall Street Journal reported the matter earlier in the day.





