Key Takeaways
- • Lone Pine Capital, the hedge fund founded by Stephen Mandel Jr., gave back its 2026 gains, with its long-short fund reportedly losing about 25% in July and 31% in the third quarter, followed by an 8.8% loss in October.
- • Year-to-date performance stood at approximately negative 7.5% before fees through the first ten months of 2026, after the fund had gained more than 40% in the first half.
- • The reversal was tied to concentrated long positions in AI infrastructure names, including about 4.3 million Nebius shares worth roughly $1.18 billion at June 30, and short positions that also lost money as AI-disrupted stocks rallied.
- • Seven of the largest U.S.-listed holdings represented about 40% of the reported U.S. equity portfolio at end-June, with five of those seven established in the second quarter.
- • As of November 9, 2026, reporting documents a severe performance reversal, not a confirmed liquidation or closure of the firm.
Summary
Lone Pine Capital, the investment firm founded by Stephen Mandel Jr., experienced one of the sharpest reversals of 2026 after entering the second half of the year on a large wave of profits from artificial intelligence investments, according to the original report. The firm's long-short hedge fund had gained more than 40% in the first half of 2026. The long-short strategy reportedly gained approximately 51% in the second quarter, while the long-only portfolio rose roughly 50%. The fund then lost approximately 25% in July and 31% in the third quarter, leaving the strategy roughly flat for the year through September. A further 8.8% loss in October left year-to-date performance at approximately negative 7.5% before fees. The firm was managing approximately $19 billion as of September.
The firm's AI positioning was central to both the rise and the decline. By June 30, Lone Pine held approximately 4.3 million shares of Nebius Group, an AI infrastructure provider, valued at roughly $1.18 billion, or about 7.2% of its reported U.S.-listed equity portfolio. Other significant holdings included Seagate Technology and Applied Materials, exposed to data storage and semiconductor equipment. Nebius fell nearly one-third from its late-June peak during July, and Applied Materials declined approximately 29% in the third quarter, as investors reassessed AI capital expenditures and valuations.
The report stresses that the losses were compounded by the structure of the portfolio. Lone Pine reportedly held long positions in AI beneficiaries alongside shorts in businesses considered vulnerable to AI disruption. When the AI narrative reversed, the long book fell while several short targets rallied, so the hedges failed to offset losses. At the end of June, seven of the largest U.S.-listed holdings made up roughly 40% of the reported U.S. portfolio, and five of those seven had been established during the second quarter.
Lone Pine was not alone. Tiger Global Management and Whale Rock Capital Management also suffered in the October selloff, with Tiger Global's hedge fund reportedly down about 8.5% in October. Citing Morgan Stanley, the report said equity-focused hedge funds reduced market exposure by roughly 9% from June, and more than 40% of stock-picking hedge funds were flat or negative year to date through October even as major U.S. equity indexes remained positive. The report concludes that AI's long-term importance is not in question, but that concentration, correlated positions, and valuation risk can undermine returns. As of November 9, 2026, the reporting describes a performance collapse rather than a confirmed closure of Lone Pine.
The firm's AI positioning was central to both the rise and the decline. By June 30, Lone Pine held approximately 4.3 million shares of Nebius Group, an AI infrastructure provider, valued at roughly $1.18 billion, or about 7.2% of its reported U.S.-listed equity portfolio. Other significant holdings included Seagate Technology and Applied Materials, exposed to data storage and semiconductor equipment. Nebius fell nearly one-third from its late-June peak during July, and Applied Materials declined approximately 29% in the third quarter, as investors reassessed AI capital expenditures and valuations.
The report stresses that the losses were compounded by the structure of the portfolio. Lone Pine reportedly held long positions in AI beneficiaries alongside shorts in businesses considered vulnerable to AI disruption. When the AI narrative reversed, the long book fell while several short targets rallied, so the hedges failed to offset losses. At the end of June, seven of the largest U.S.-listed holdings made up roughly 40% of the reported U.S. portfolio, and five of those seven had been established during the second quarter.
Lone Pine was not alone. Tiger Global Management and Whale Rock Capital Management also suffered in the October selloff, with Tiger Global's hedge fund reportedly down about 8.5% in October. Citing Morgan Stanley, the report said equity-focused hedge funds reduced market exposure by roughly 9% from June, and more than 40% of stock-picking hedge funds were flat or negative year to date through October even as major U.S. equity indexes remained positive. The report concludes that AI's long-term importance is not in question, but that concentration, correlated positions, and valuation risk can undermine returns. As of November 9, 2026, the reporting describes a performance collapse rather than a confirmed closure of Lone Pine.
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