Jazz Pharmaceuticals plc (JAZZ) Jumps Nearly 30% on Strong Q3 and Cancer Drug Trial Progress

The Harbor Capital Advisors released its “Mid Cap Value Fund’s” Q4 2025 investor letter. A copy of the letter can be downloaded here. Harbor Mid Cap Value Fund, subadvised by LSV Asset Management, delivered solid outperformance in the fourth quarter of 2025, with the Institutional Class returning 4.07% versus 1.42% for the Russell Midcap Value Index, benefiting from strength in value stocks as the Russell Midcap Growth Index declined 3.7% during the period. U.S. equities broadly advanced, with the S&P 500 Index rising 2.7% in the quarter and 17.9% for the full year, while mid-caps lagged, with the Russell Midcap Index up just 0.2% in Q4. For 2025, the Fund gained 15.95% (Institutional Class), outperforming the benchmark’s 11.05% return. Attribution data show a total quarterly excess return of 2.82%, largely from selection effects, underscoring the manager’s quantitative value discipline focused on fundamental undervaluation, improving momentum, and risk control. Looking ahead, management noted that while AI-driven large-cap leadership has elevated valuations in certain segments, mid- and small-cap value stocks continue to trade at more attractive multiples, positioning the Fund to capitalize on opportunities within economically sensitive and cash-generative businesses. In addition, please check the Fund’s top five holdings to know its best picks in 2025.

In its fourth-quarter 2025 investor letter, Harbor Capital Advisors' Mid Cap Value Fund highlighted stocks like Jazz Pharmaceuticals plc (NASDAQ:JAZZ). Jazz Pharmaceuticals plc (NASDAQ:JAZZ) is a biopharmaceutical company specializing in treatments for sleep disorders, epilepsy, and oncology with a focus on high-value specialty medicines. The one-month return of Jazz Pharmaceuticals plc (NASDAQ:JAZZ) was 14.88% while its shares traded between $95.49 and $198.00 over the last 52 weeks. On February 26, 2026, Jazz Pharmaceuticals plc (NASDAQ:JAZZ) stock closed at approximately $188.97 per share, with a market capitalization of about $11.483 billion.

Harbor Capital Advisors' Mid Cap Value Fund stated the following regarding Jazz Pharmaceuticals plc (NASDAQ:JAZZ) in its Q4 2025 investor letter:

"Jazz Pharmaceuticals plc (NASDAQ:JAZZ), in the Health Care sector, was a top performer, advancing nearly 30% driven by strong third quarter performance and positive clinical trial results for one of its cancer drugs. We continue to hold the company in the Fund."

Jazz Pharmaceuticals plc (NASDAQ:JAZZ) is not on our list of 30 Most Popular Stocks Among Hedge Funds. As per our database, 64 hedge fund portfolios held Jazz Pharmaceuticals plc (NASDAQ:JAZZ) at the end of the fourth quarter, which was 49 in the previous quarter. While we acknowledge the risk and potential of Jazz Pharmaceuticals plc (NASDAQ:JAZZ) as an investment, our conviction lies in the belief that some AI stocks hold greater promise for delivering higher returns and doing so within a shorter time frame. If you're looking for an extremely undervalued AI stock that also stands to benefit significantly from Trump-era tariffs and the onshoring trend, see our free report on the best short-term AI stock.

In another article, we covered Jazz Pharmaceuticals plc (NASDAQ:JAZZ) and shared the list of mid-cap stocks to buy according to top investors. In addition, please check out our hedge fund investor letters Q4 2025 page for more investor letters from hedge funds and other leading investors.

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Disclosure: None. This article is originally published at Insider Monkey.