Key Highlights

● Boston Scientific's sales growth slowed in the quarter.

● The company guided Q4 sales below the prior-year level.

● An August cybersecurity incident weighed on results.

● CEO Mike Mahoney called 2026 a challenging year.

Boston Scientific shares slid after the medical-device maker reported slowing sales growth and guided fourth-quarter sales below the prior year's level, citing the fallout from an August cybersecurity incident.

Boston Scientific (NYSE:BSX) slid on Wednesday, October 28, one of the more notable decliners in the S&P 500 on a day when the broader market edged higher.

Slower Growth Meets a Weaker Outlook

Boston Scientific has been one of the stronger large-cap health-care stories in recent years, with investors rewarding it for steady growth across its cardiology and medical-surgical businesses. That track record raised the bar for this report.

Slowing sales growth would have been enough to test sentiment on its own. Guiding fourth-quarter sales below the prior-year quarter added another layer of disappointment, signalling that the effects of the August incident were still being felt. Chief executive Mike Mahoney described 2026 as a challenging year, according to reports of the company's comments.

A Deep Opening Drop, Then a Partial Recovery

The stock was down far more early in the session than it was at the close, according to market reports, which differed on the size of the decline at various points in the day. The shares recovered some ground by the final bell but still finished firmly lower.

That pattern of a deep opening drop followed by a partial rebound is common when a well-regarded company issues disappointing guidance. Investors initially rush to reprice expectations, then some see value once the dust settles.

Health Care Holds Up, But Not for BSX

The decline came even though health care was one of eight S&P 500 sectors that finished higher on Wednesday. GE HealthCare (NASDAQ:GEHC) rose after raising its full-year guidance, and Labcorp (NYSE:LH) also gained, underlining that the selling in Boston Scientific was company-specific rather than a sector-wide retreat.

The broader market took its cue from the Federal Reserve, which left its benchmark rate range unchanged in a 10-2 vote. The S&P 500 rose 21.38 points to 7,743.98, its third straight gain, while chipmakers and AI-infrastructure names led.

What to Watch

The key question for Boston Scientific is whether management can show that the hit from the August cyber incident is temporary. Investors will watch for analyst estimate revisions and any further commentary on fourth-quarter trends.

For the wider market, Thursday brings the advance estimate of third-quarter GDP and September PCE inflation at 8:30 a.m. ET. Merck (NYSE:MRK), Mastercard (NYSE:MA) and Caterpillar (NYSE:CAT) report before the open, while Amazon (NASDAQ:AMZN) reports after the close.