Longleaf Partners, managed by Southeastern Asset Management, recently released its first-quarter 2026 investor letter. The Fund reported a return of -4.46% for the quarter, slightly underperforming the S&P 500 and Russell 1000 Value Index. The market experienced turbulence in the wake of the Iran War and increasing private credit risks, leading to sector-wide movements influenced by perceived AI outcomes.
Despite initially lagging behind the market, the Fund saw improved performance as conditions worsened. By the end of the quarter, the Fund’s P/V stood at mid-50s%, indicating promising future returns. Investors can access a copy of the full investor letter for more details on the Fund’s performance and outlook for 2026.
One of the highlighted investments in the first-quarter letter was Avantor, Inc. (NYSE:AVTR). Based in Radnor, Pennsylvania, Avantor provides essential products and services to biotechnology, education, and pharmaceutical companies. The stock closed at $7.62 per share on May 15, 2026, with a one-month return of -10.35% and a 52-week loss of 42.96%.
Longleaf Partners Fund expressed optimism about Avantor in its letter, despite a decline in stock price attributed to lower-than-expected 2026 revenue outlooks from new CEO Emmanuel Ligner. The Fund believes that production inefficiencies are fixable, especially with the appointment of Mary Blenn as COO, bringing valuable supply chain and operational experience to the company. Avantor continues to generate solid free cash flow, and recent open-market purchases by directors demonstrate confidence in the company’s future prospects.
While Avantor is not among the 40 most popular stocks held by hedge funds, it remains a compelling investment opportunity. In Q1 2026, the company reported $1.58 billion in revenue, showing resilience despite a slight decline on an organic basis. For investors seeking undervalued AI stocks with significant potential upside, exploring other options in the market may offer greater returns with less downside risk.
Overall, Longleaf Partners Fund’s strategic investments in companies like Avantor reflect its commitment to identifying promising opportunities for growth and value creation. As the market continues to evolve, staying informed about the Fund’s top holdings and investment strategies can provide valuable insights for investors seeking long-term success.

