Why Tandem Diabetes (TNDM) Shares Are Trading Lower Today

September 25, 2025 at 12:45 PM EDT

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What Happened?

Shares of diabetes technology company Tandem Diabetes Care (NASDAQ: TNDM) fell 5.5% in the afternoon session after the U.S. government opened an investigation into the national security implications of medical equipment and device imports.

The Commerce Department initiated a Section 232 investigation that covered a wide range of healthcare products, including items like blood glucose monitors, which are relevant to Tandem's business. This review evaluated U.S. demand, domestic manufacturing capacity, and the impact of imports. A key part of the investigation was to determine if tariffs or quotas should be used to protect national security. This created uncertainty and concern over potential cost increases for medical device companies, impacting investor sentiment.

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What Is The Market Telling Us

Tandem Diabetes’s shares are extremely volatile and have had 36 moves greater than 5% over the last year. In that context, today’s move indicates the market considers this news meaningful but not something that would fundamentally change its perception of the business.

The previous big move we wrote about was 7 days ago when the stock gained 5% after the company announced the publication of a study showing its automated insulin delivery system was beneficial for adults with type 2 diabetes, while a broader market rally fueled by a Federal Reserve interest rate cut also provided a tailwind.

The study, published in the American Diabetes Association's Diabetes Care journal, found that the Control-IQ+ system helped adults with insulin-treated type 2 diabetes, regardless of their C-peptide levels.

This positive news arrived in a favorable market environment. The U.S. Federal Reserve initiated its first interest rate cut of 2025, which buoyed investor sentiment and sent stocks higher for a third straight session. Capital-intensive sectors like biotechnology and healthcare particularly benefited from the signal of improved funding conditions. The specific clinical update, combined with the broader economic tailwind, helped lift the shares.

Tandem Diabetes is down 66.8% since the beginning of the year, and at $11.90 per share, it is trading 73.3% below its 52-week high of $44.64 from September 2024. Investors who bought $1,000 worth of Tandem Diabetes’s shares 5 years ago would now be looking at an investment worth $109.82.

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Why Tandem Diabetes (TNDM) Shares Are Trading Lower Today

What Happened?

What Is The Market Telling Us

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