What happened

Shares of Viela Bio (VIE) were soaring Monday morning after it was announced that the biopharmaceutical company will soon be acquired by Horizon Therapeutics (HZNP). As of 11:27 a.m. EST, shares of Viela Bio were up by 52.5%.

So what

Horizon Therapeutics will acquire all the outstanding shares of Viela Bio for $53 per share in cash. The price of this transaction represents a significant premium over Viela's stock price as of the closing of Friday's trading, which was $34.68.

That explains why investors rapidly bid up Viela Bio's shares this morning. Tim Walbert, CEO of Horizon Therapeutics, said, "This acquisition represents a significant step forward in advancing our strategy -- to expand our pipeline in order to accelerate our growth over the long term."

Letter blocks spelling "M&A."

Image source: Getty Images.

Perhaps the most important asset Horizon will get as part of this acquisition is Uplizna, a medicine for a rare autoimmune condition called neuromyelitis optica spectrum disorder (NMOSD). Uplizna is the only drug approved by the Food and Drug Administration for NMOSD.

"We are pleased that Horizon recognizes the value of our robust R&D pipeline; our commercial medicine Uplizna, which is an important treatment option for patients with NMOSD; and our talented team," said Bing Yao, CEO of Viela Bio. Horizon will also inherit Viela Bio's pipeline, including potential treatments for rheumatoid arthritis and more.

Now what

The transaction between these two healthcare companies is structured as a two-step cash tender offer, whereby Horizon Therapeutics will acquire all the remaining shares of Viela Bio (those not tendered through the offer) through a merger, still at the price of the tender offer ($53 per share). The deal is expected to close by the end of the first quarter.