Should You Be Excited for Regeneron (REGN)?

Longleaf Partners, managed by Southeastern Asset Management, released its fourth-quarter 2025 investor letter. A copy of the letter can be downloaded here. The Fund returned 3.35% in the quarter, compared to the S&P 500’s 2.66% and the Russell 1000 Value Index’s 3.81% return. 2025 was a challenging year for the firm, as it did not have any standout performers. Approximately 5% of the portfolio gained 20% or more, while 35% of the S&P 500 hit that level. The overall market dynamic drove the Fund’s underperformance. The firm focuses on actions to strengthen portfolio outcomes rather than chasing winners at the wrong time. The firm reiterates that building a portfolio of real companies on offense in a period of excessive speculation will benefit all markets. In addition, please check the Fund’s top five holdings to know its best picks in 2025.

In its fourth-quarter 2025 investor letter, Longleaf Partners Fund highlighted stocks such as Regeneron Pharmaceuticals, Inc. (NASDAQ:REGN). Headquartered in Tarrytown, New York, Regeneron Pharmaceuticals, Inc. (NASDAQ:REGN) is a biotechnology company. On January 16, 2026, Regeneron Pharmaceuticals, Inc. (NASDAQ:REGN) stock closed at $733.04 per share. One-month return of Regeneron Pharmaceuticals, Inc. (NASDAQ:REGN) was -5.94%, and its shares gained 7.55% of their value over the last 52 weeks. Regeneron Pharmaceuticals, Inc. (NASDAQ:REGN) has a market capitalization of $77.693 billion.

Longleaf Partners Fund stated the following regarding Regeneron Pharmaceuticals, Inc. (NASDAQ:REGN) in its fourth quarter 2025 investor letter:

"Regeneron Pharmaceuticals, Inc. (NASDAQ:REGN) – Healthcare company Regeneron was a detractor in the first half of the year but ended up as a contributor for the quarter and full year. It did not initially feel great, but our phased buy-in has worked well so far. We continue to like the company’s strong position in allergic diseases (DUPIXENT) and oncology (LIBTAYO and others). We believe the market focuses too much on EYLEA, a retinal disease medication which is less than 20% of the company's value. The company has a net cash balance sheet and great owner-partners. Unlike most others in its industry, it has sworn off large M&A and was a material share repurchaser in 2025. We still are not paying much (or anything depending on how you do the math) for the company’s sizeable pipeline value. After some initial pipeline disappointment in the first part of the year, there were more positives as the year went on. The P/V remains low, and we are excited for Regeneron to be a meaningful position entering the year."

Regeneron Pharmaceuticals, Inc. (NASDAQ:REGN) is not on our list of 30 Most Popular Stocks Among Hedge Funds. According to our database, 78 hedge fund portfolios held Regeneron Pharmaceuticals, Inc. (NASDAQ:REGN) at the end of the third quarter, up from 73 in the previous quarter. While we acknowledge the potential of Regeneron Pharmaceuticals, Inc. (NASDAQ:REGN) as an investment, we believe certain AI stocks offer greater upside potential and carry less downside risk. 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 Regeneron Pharmaceuticals, Inc. (NASDAQ:REGN) and shared the list of best debt-free stocks to invest in. 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.