BSX · Boston Scientific

The thesis

Boston Scientific shares are more likely to lag the S&P 500 over the next three months. An August cyberattack, falling Watchman sales and lost share in electrophysiology have turned fourth-quarter sales guidance negative, and management has warned that 2027 will be hard. The fourth-quarter report, expected around 4 February 2027 with the first 2027 guidance, decides whether the low valuation has already priced the worst.

The third-quarter report of 28 October 2026 shows the break. Sales were $5.138 billion, up 1.5% from a year earlier, against 9.5% growth in the first half (TIKR, 28 October 2026). The company guided fourth-quarter sales to fall 1%–3% and cut full-year adjusted earnings per share (EPS) guidance to $3.16–$3.18 from $3.28–$3.32. Chief executive Michael Mahoney said the company "will be challenged to grow sales and adjusted EPS next year" excluding the pending Penumbra acquisition.

The market has priced a reset. The 12 November 2026 close of $44.20 is 58.2% below the 52-week high of $105.65 (13 November 2025), and TIKR put the forward price-to-earnings ratio near 13.5 on 28 October 2026, against a five-year average of 26. The rating is Low because no dated event before the February report is likely to show recovery, and management has already said 2027 guidance will show little growth.

Bullish and bearish views on Boston Scientific Corporation

The bull case on Boston Scientific Corporation (BSX), in brief: valuation sits near five-year lows. The bear case: the cyberattack sent orders to rivals.

Bull case

• Valuation sits near five-year lows. TIKR reported on 28 October 2026 that the forward price-to-earnings ratio briefly matched June's five-year low of about 12.4 before settling near 13.5, against a 38 peak in February 2025.
• New Watchman trial data. On 2 November 2026 the company reported that the SIMPLAAFY randomized trial of Watchman FLX Pro met its six-month primary endpoint; the shares rose 5.6% that session while the S&P 500 fell 0.5% (Trefis, 3 November 2026). The Elite AF trial of the next-generation Watchman Elite has begun enrolling (third-quarter release, 28 October 2026).
• Outside money for the heart pump. Blackstone Life Sciences agreed on 2 November 2026 to co-fund development of the Vitalyst temporary heart pump with $455 million, which shares the cost of a program that has not yet earned revenue.
• Parts of the business still grow. Neuromodulation sales rose 13.0% organically to $331 million and EMEA sales rose 6.1% operationally in the third quarter of 2026 (company release, 28 October 2026).
• A director bought before the guidance cut. Director Susan Morano bought 2,040 shares in the open market at $49.22 on 25 August 2026 (SEC Form 4), above the current price.

Bear case

• The cyberattack sent orders to rivals. The August attack shut every plant and distribution center for eight days, and Mahoney said "some hospitals likely ordered from others" (TIKR, 28 October 2026). The company put the cost at about 300 basis points of third-quarter growth, with more drag in the fourth quarter (Citeline, 28 October 2026).
• Watchman has turned to decline. Watchman sales fell 6% in the third quarter of 2026 after growing nearly 30% in 2025, and management assumes Watchman market conditions do not improve in 2027 (TIKR and the earnings call, 28 October 2026).
• Electrophysiology share is eroding. Management said on 28 October 2026 that its strong electrophysiology share has eroded as new technologies entered the market, and that the cyberattack sped up the shift.
• Guidance cut three times this year. Full-year 2026 sales growth guidance fell to about 4.25%, from 5.5%–6.5% in July and 10.5%–11.5% in February (TIKR, 28 October 2026). Fourth-quarter adjusted EPS guidance of $0.77–$0.79 compares with the $0.83 analysts expected before the report.
• Analysts have moved to neutral. After the report, Jefferies (29 October 2026) and TD Cowen (30 October 2026) downgraded to Hold with $46 targets, JPMorgan moved to Neutral and cut its target to $46 from $56, Barclays cut its target to $45, and RBC cut its target to $52 from $70 while keeping Outperform.
• Penumbra adds integration work in a trough year. The $14.5 billion Penumbra acquisition, agreed in January 2026, is expected to close in early 2027 and is excluded from guidance (third-quarter call, 28 October 2026).

Price setup

• The shares closed at $44.20 on 12 November 2026. The 50-day moving average is $44.06 and the 200-day moving average is $54.38, both as of that close. The price sits on the 50-day average and well below the 200-day.
• The 52-week closing low is $41.58, set on 7 October 2026. The lowest close of the post-report period shown here, $42.75 on 6 November 2026, stayed above it.
• From 5 November to 12 November 2026, closes ranged from $42.75 to $45.13. The positive Watchman data and the Blackstone funding did not lift the shares out of that range.
• The three-month price change is −14.7%. That period began before the company disclosed the cyberattack on 26 August 2026 and covers the guidance cut on 28 October 2026.
• Analyst targets set after the report cluster at $45–$52, close to the current price, which leaves the shares without a valuation pull from the sell side.

Catalysts ahead

• ~4 February 2027 (est.): Fourth-quarter 2026 results and first full-year 2027 guidance. Shows whether fourth-quarter sales fell as guided and how much growth management sees for 2027 after warning it will be challenged to grow sales and adjusted EPS.
• Early 2027 (est.): Expected closing of the $14.5 billion Penumbra acquisition. Adds a growing thrombectomy business that current guidance excludes, and adds integration work and share dilution in a year management already calls difficult.

What would change the view

A daily close above $51.83, the 14 August 2026 close, which would erase the three-month loss and show the shares leading; or fourth-quarter 2026 sales that grow from a year earlier, against guidance for a 1%–3% decline.

What it trades with

• Company-specific events drive the stock. Over the twelve months to early November 2026 the shares fell 56.8% while the S&P 500 returned 9.8% (StockStory via Yahoo Finance, 7 November 2026).
• Within medical devices, the shares are tied to the left atrial appendage closure market (Watchman) and to competition in pulsed-field ablation for atrial fibrillation, where management said on 28 October 2026 that newer rival technologies took share.
• Penumbra shareholders can choose 3.8721 Boston Scientific shares for each Penumbra share, subject to proration, under the January 2026 deal terms. Until the deal closes, Penumbra's share price partly tracks Boston Scientific's.