Arena Pharmaceuticals will be acquired by Pfizer in a $6.7 billion agreement.

Pfizer Inc. PFE, +1.34 percent announced Monday that it has agreed to purchase Arena Pharmaceuticals Inc. ARNA, -5.33 percent in a $6.7 billion deal. Arena stock jumped 91 percent in premarket trading as a result of the news. Pfizer will pay $100 for each Arena share, or more than quadruple the stock’s Friday closing price of $49.94. According to Mike Gladstone, global president, and general manager of Pfizer’s inflammation and immunology division, the acquisition will result in a company with greater expertise in inflammation and immunology. “Arena has established a robust development program for etrasimod, which includes two Phase 3 studies in ulcerative colitis (UC), a Phase 2/3 program in Crohn’s Disease, a planned Phase 3 program in atopic dermatitis, and ongoing Phase 2 studies in eosinophilic esophagitis and alopecia areata,” the companies said in a statement. Pfizer expects to fund the transaction using cash on hand. Pfizer’s stock rose 1.8 percent in premarket trading as a result of the announcement.