What Happened?

Shares of diabetes technology company Tandem Diabetes Care (NASDAQ: TNDM) jumped 30.2% in the afternoon session after the company reported better-than-expected fourth-quarter financial results. 

The medical device maker posted quarterly sales of $290.4 million, a 15% increase year-on-year that surpassed analyst estimates. The company also recorded a much smaller-than-expected loss of just one cent per share. While this was a slight decline from the one-cent profit reported in the same quarter last year, it handily beat forecasts. Investors appeared to focus on the strong quarterly performance and improved operating margins, driving the stock higher despite the company issuing a 2026 sales forecast that was slightly below market expectations.

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What Is The Market Telling Us

Tandem Diabetes’s shares are extremely volatile and have had 41 moves greater than 5% over the last year. But moves this big are rare even for Tandem Diabetes and indicate this news significantly impacted the market’s perception of the business.

The biggest move we wrote about over the last year was 4 months ago when the stock gained 20.3% on the news that the company reported third-quarter results that surpassed analyst expectations for both revenue and earnings per share. 

For the quarter, Tandem posted revenue of $249.3 million, a 2.2% year-over-year increase, which was well ahead of the consensus estimate of $236 million. The company's loss per share came in at $0.31, narrower than the $0.32 loss that analysts had predicted. The results were also bolstered by an improvement in operational efficiency, as the company's operating margin increased to -9.2% from -10.7% in the same period a year ago. Overall, it was a strong quarter that significantly exceeded Wall Street's expectations.

Tandem Diabetes is up 12.7% since the beginning of the year, but at $24.28 per share, it is still trading 27.7% below its 52-week high of $33.59 from February 2025. Investors who bought $1,000 worth of Tandem Diabetes’s shares 5 years ago would now be looking at an investment worth $261.37.

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