Bristol Myers Squibb and AstraZeneca reportedly considering a $400 billion merger.

U.K. drugmaker AstraZeneca and New Jersey-based Bristol Myers Squibb are reportedly in early-stage talks for a merger that could create the world's fourth-largest drugmaker by market value and largest by revenue. The potential deal, valued at approximately $400 billion, would unite two major oncology players, though investors are reportedly questioning its strategic value and potential integration challenges.