Boston Scientific (BSX) Shares Plunge 9% on Watchman Device Concerns and Rating Cut

Key Takeaways

• Shares of BSX tumbled 9% to $62.93, marking the lowest closing price since January 2024
• The CHAMPION-AF trial showed Watchman FLX was non-inferior to blood thinners, though a 3.2% ischemic stroke rate (versus 2% for anticoagulants) concerned investors
• Raymond James lowered BSX from Strong Buy to Outperform and reduced its price target from $97 to $88
• The rating adjustment reflected decelerating momentum in U.S. electrophysiology and Watchman segments, which together drove more than 50% of annual growth
• Year-to-date, BSX has declined 34%, significantly underperforming the S&P 500’s 7.1% drop

Boston Scientific faced a challenging trading session Monday as shares plummeted 9% following a double blow: clinical trial results that raised investor eyebrows and a subsequent analyst downgrade.

Boston Scientific Corporation, BSX

Presented on March 30 at a major medical conference, the CHAMPION-AF trial evaluated the Watchman FLX left atrial appendage closure device. The headline findings appeared encouraging: the device met its primary endpoint by demonstrating non-inferiority to contemporary oral anticoagulants such as Eliquis and Xarelto. Additionally, patients treated with Watchman experienced reduced non-procedural bleeding complications.

However, market participants fixated on a secondary metric. Trial participants who received the Watchman device experienced ischemic strokes at a rate of 3.2%, compared with 2% among those taking blood thinners. Despite the modest absolute difference, this discrepancy triggered significant selling pressure.

Importantly, researchers noted that this variance lacked statistical significance and wasn’t designated as a primary study outcome. The trial team intends to monitor participants for five years to develop more comprehensive long-term stroke risk data.

Medical Experts Defend Trial Outcomes

Marty Leon, the study’s co-chair, characterized the findings as “a very strong endorsement” supporting broader device utilization. He highlighted the risk-benefit calculation: an annualized 0.33% increase in stroke or embolization events balanced against approximately 2.6% reduction in bleeding complications. Boston Scientific’s chief medical officer, Ken Stein, reinforced this perspective, emphasizing that stroke incidence remained “incredibly low” across both treatment arms.

Truist Securities reported overwhelmingly positive sentiment from conference attendees. Leerink Partners indicated that firsthand discussions with physicians strengthened their confidence that the data would support accelerating Watchman procedure adoption.

Nevertheless, the market reacted negatively. BSX finished the session at $62.93, representing its weakest close since January 30, 2024.

Compounding the pressure, Raymond James simultaneously downgraded BSX from Strong Buy to Outperform while slashing its price objective from $97 to $88. The firm highlighted weakening traction in two critical growth drivers: domestic electrophysiology and Watchman procedures, which collectively represented 26% of 2025 revenues and contributed over half of year-over-year expansion.

Raymond James Maintains Positive Outlook Despite Reduced Estimates

Raymond James analyst Jayson Bedford clarified that the rating change didn’t reflect fundamental concerns about the company’s prospects. The firm continues to regard Boston Scientific as among the premier growth stories in large-cap medical device companies. Rather, the adjustment stemmed from diminished near-term visibility rather than deteriorating long-range fundamentals.

The investment bank reduced its 2026 and 2027 revenue projections by approximately 0.5% and 1.5% respectively. Updated forecasts anticipate Watchman growth of 17% and 16% over the coming two years, down from previous expectations of 18% and 20%. Electrophysiology growth estimates were similarly adjusted to 15% and 14%.

Despite these revisions, Raymond James emphasized that valuation metrics remain compelling. BSX currently trades at roughly 18 times estimated 2027 earnings, compared to 21 times for comparable medical technology peers.

Numerous other research firms — including Bernstein, Evercore ISI, Stifel, Truist, and Jefferies — maintain Buy or Outperform recommendations, with price targets spanning $88 to $120.

BSX has retreated 34% year-to-date. The stock previously reached a 52-week peak of $110 earlier this year.