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AZN shares post their worst session since 2020 on unconfirmed merger talk with BMY

8/15/2026

Reports of merger discussions between AstraZeneca PLC (NYSE: AZN) and Bristol-Myers Squibb Company (NYSE: BMY) sent AZN shares down as much as 9% on Monday, the stock's steepest one-day drop since 2020.

Neither company confirmed the talks. People familiar with the matter told Reuters the deal may never materialize, and the market's reaction suggests most AstraZeneca investors are counting on exactly that.

The split in the tape was hard to miss. Bristol-Myers shares climbed as much as 6% on the same news before pulling back.

A combined entity would carry a market value of close to $400 billion, placing it fourth-largest among global drugmakers.