Why Protagonist Therapeutics Stock Skyrocketed by Almost 30% Today

Clinical-stage biotech Protagonist Therapeutics (NASDAQ: PTGX) was all the rage on the stock market Friday. The company's share price closed a dizzying 29.8% higher on the day, thanks to intense takeover speculation. That leap was particularly notable considering it was quite a downbeat day for stocks overall, with the S&P 500 (SNPINDEX: ^GSPC) sliding by almost 3%.

Sale in the works?

That speculation was fired that morning by The Wall Street Journal, which reported healthcare giant Johnson & Johnson was in discussions to acquire Protagonist. Although it gleaned this from unidentified "people familiar with the matter," the financial newspaper had few details to report about the apparent negotiations.

Image source: Getty Images.

Protagonist is well known to Johnson & Johnson, as the two companies collaborate on the development of a drug that combats immune disorders such as ulcerative colitis. If and when the medication is developed successfully and comes to market, Johnson & Johnson will hold its exclusive commercialization rights.

If the report is accurate, the would-be acquirer wouldn't be snapping up Protagonist at a bargain. Thanks largely to positive results in clinical trials for several of its pipeline drugs, the biotech's share price had risen in excess of 70% year to date -- and that was before Friday's monster pop.

Mum's the word... for now

Neither Protagonist nor Johnson & Johnson has yet commented on the WSJ report, which is par for the course in early stages of such events. I should stress that this has to be considered speculation at this point, although I would advise investors of either company (or both) to keep a sharp eye on how the apparent deal might shape up.

Eric Volkman has no position in any of the stocks mentioned. The Motley Fool recommends Johnson & Johnson and Protagonist Therapeutics. The Motley Fool has a disclosure policy.