Key Highlights

● CEO Mike Mahoney called the period a challenging year.

● Shares were down more sharply early in the session than at the close.

● The company cited an August cybersecurity incident.

● Health care overall still finished higher that day.

Boston Scientific's chief executive called 2026 a challenging year as slowing sales and a softer fourth-quarter outlook tied to an August cyber incident pushed the shares lower.

Three words from the top of Boston Scientific summed up why its stock struggled on Wednesday, October 28. Chief executive Mike Mahoney described the period as a challenging year, according to reports of the company's comments, and investors took the message to heart.

From Early Rout to Partial Recovery

Boston Scientific (NYSE:BSX) slid on the S&P 500 after the medical-device maker reported slowing sales growth and trimmed its forecast. The company guided fourth-quarter sales below the level of a year earlier and cited a cybersecurity incident in August among the factors that hurt results.

The shares were hit hardest in the morning. Reports differed on the size of the decline, with the stock down far more early in the session than at the close. Buyers stepped in as the day wore on, but Boston Scientific still finished clearly in the red.

Why the Outlook Mattered

Boston Scientific has long been a favorite among large-cap health-care investors, valued for consistent growth across its cardiology, electrophysiology and medical-surgical franchises. Reliable growth stories tend to command premium valuations, which leaves less tolerance for slip-ups.

This report delivered two disappointments at once. Sales growth slowed, and the fourth-quarter outlook pointed to sales below the prior-year quarter. That second point suggested the effects of the August cyber incident had not been fully put behind the company.

A Market Led by Chips and AI

Boston Scientific's slide stood out on a day when health care was among the eight S&P 500 sectors to finish higher. GE HealthCare (NASDAQ:GEHC) and Labcorp (NYSE:LH) both rose after raising their outlooks, highlighting the company-specific nature of the selling.

The broader market was driven by the Federal Reserve, which left its benchmark rate range unchanged in a 10-2 vote. The S&P 500 closed up 21.38 points at 7,743.98, its third straight gain, while chipmakers extended their rally, with the Philadelphia Semiconductor Index rising for a fourth straight session to 11,684.00.

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, and Amazon (NASDAQ:AMZN) reports after the close.