By Maria Armental

Pfizer Inc.'s stock gained 5% to $55.53 after reaching a $6.7 billion deal to acquire Arena Pharmaceuticals Inc.

Pfizer's stock on Monday traded as high as $55.73, making it the second best performer on the S&P 500 by percentage gain on Monday, behind Moderna Inc., according to FactSet.

Arena's stock surged 80% to $90.01, snapping a two-day losing streak and on track for the largest one-day percent increase on record.

Pfizer said it would pay $100 a share for Arena, more than double Friday's closing price of $49.94.

Arena could be a significant revenue contributor for Pfizer from 2025 to 2030, said Mike Gladstone, Pfizer's global president for inflammation and immunology.

At the heart of the deal is Arena's lead drug, etrasimod.

In addition to etrasimod's potential near-term launch as an ulcerative colitis treatment, company officials pointed to its potential for patients with other indications, such as Crohn's disease or atopic dermatitis.

The deal is expected to close in the first half of 2022, pending regulatory approvals.

Write to Maria Armental at maria.armental@wsj.com

(END) Dow Jones Newswires

12-13-21 1342ET