Pfizer (PFE) shares plunged 5.02% in intraday trading on Friday, as President Donald Trump's latest tariff warnings sent shockwaves through the pharmaceutical sector. The dramatic decline comes as part of a broader sell-off in drug stocks, with several major players in the industry facing significant losses.

Trump's announcement that tariffs on the pharmaceutical sector are "under review" and expected to be announced in the near future has sparked concerns among investors. This potential shift in trade policy could have far-reaching implications for the industry, which has long benefited from tariff exemptions on imported pharmaceutical products.

According to estimates by Bernstein analyst Courtney Breen, the proposed tariffs could add approximately $46 billion in import costs for the pharmaceutical industry if implemented. This substantial increase in expenses could potentially lead to earnings contractions for affected companies and force them to reconsider their manufacturing strategies and global footprints.

The threat of tariffs poses particular challenges for companies like Pfizer, which have significant manufacturing operations in countries with lower corporate tax rates, such as Ireland and Switzerland. The implementation of tariffs could offset the tax benefits these companies currently enjoy, potentially impacting their bottom lines and competitive positions in the global market.

As investors grapple with the uncertainty surrounding these potential trade policy changes, the pharmaceutical sector may face continued volatility in the coming weeks. The industry's response to these challenges and any further developments in trade negotiations will be closely watched by market observers.