Novartis AG agreed to buy biotech firm Avidity Biosciences in a deal that values Avidity at around $12 billion, it announced on Sunday.

Avidity Biosciences rose 43% in premarket trading.

The Swiss drugmaker is paying $72 a share cash for the San Diego-based biotech, about a 46% premium to Avidity's closing price on Friday. The deal has already been approved by the boards of both companies.

Novartis said the acquisition aligns with its long-term strategy and expands its pipeline of treatments with potential near-term launches of drugs for genetically defined diseases. Avidity's drugs include late-stage therapies for the treatment of neuromuscular diseases.

The acquisition would raise the 2024-2029 expected sales compound annual growth rate for Novartis to 6% from 5%, it said.

"The Avidity team has built robust programs with industry leading delivery of RNA therapeutics to muscle tissue," Novartis CEO Vas Narasimhan said. "We look forward to developing these programs to meaningfully change the trajectory of diseases for patients."