Miami billionaire Ken Griffin is making big moves on Wall Street. What’s he buying?

Miami billionaire Ken Griffin is accustomed to making headlines for what he is building, buying or reshaping in South Florida.

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The Citadel founder has become one of the most influential figures in Miami’s transformation into a major financial and business center with his real estate purchases from Coconut Grove to West Palm Beach.

But over the past week, it’s been revealed in finance circles that Griffin, who manages one of the world’s largest hedge funds, has been making news for practicing his profession: buying and selling stocks.

His latest portfolio moves involve two pharmaceutical companies and a troubled artificial intelligence company are giving investors a glimpse into how one of the world’s most closely watched hedge fund managers is navigating an expensive and increasingly volatile market.

In the Situational Awareness fund move, Griffin sent investors a letter explaining Citadel’s stock actions with the AI company.

In the case of the two pharma companies, they were made public in the hedge fund’s Form 13F, a quarterly report filed with the U.S. Securities and Exchange Commission by institutional investment managers with at least $100 million in qualifying assets.

Here’s what to know:

Griffin goes big on Eli Lilly

In the latest move this week, financial reports show, Citadel nearly quadrupled its position in Eli Lilly during the second quarter, adding roughly 700,000 shares and bringing its holdings to about 945,000 shares, worth roughly $1.2 billion at the time of the filing.

The move puts Lilly among Citadel’s largest individual stock positions and comes after the pharma giant’s shares suffered a sharp decline earlier this year before rebounding.

Lilly’s weight-loss drugs Mounjaro and Zepbound have made it a dominant player in the booming diabetes and obesity-treatment markets. The company reported roughly $23 billion in second-quarter revenue, up 48% from a year earlier, with Mounjaro generating about $9.9 billion and Zepbound approximately $4.9 billion.

The investment also gives Griffin exposure to Lilly’s Alzheimer’s drugs. The company’s Kisunla treatment received FDA approval in 2024 for certain patients with early symptomatic Alzheimer’s disease.

There is a notable Miami connection to Griffin’s philanthropy. In 2024, Griffin donated $50 million to Baptist Health Miami Neuroscience Institute, helping establish the Kenneth C. Griffin Center for neurological care and research at the Kendall hospital.

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Griffin ads AbbVie as second pharma bet

Lilly wasn’t Griffin’s only major pharmaceutical move. Citadel increased its AbbVie position by roughly 547% during the second quarter, adding about 2.7 million shares and ending the period with approximately 3.2 million shares worth around $800 million.

AbbVie offers a different investment profile from Lilly, with established drugs including Skyrizi, Rinvoq and Botox and a dividend that has increased for more than five decades.

The two investments together suggest Citadel is looking beyond a single pharmaceutical trade, pairing Lilly’s high-growth story with AbbVie’s established products and cash generation, experts say.

Griffin gives ‘master class’

The phrase “masterclass” is actually tied to Griffin’s handling of an entirely different trade: the collapse of AI-focused hedge fund Situational Awareness.

The fund, founded by former OpenAI researcher Leopold Aschenbrenner, suffered a 67% decline in July as heavily concentrated AI-related positions plunged.

Then Citadel stepped in to purchase much of the distressed portfolio at a discount.

Citadel subsequently sold more than 80% of the acquired exposure through nearly 100 block trades worth more than $4 billion in market value, according to reports.

24/7 Wall St. described the maneuver as a “master class.” referring to Griffin’s ability to provide liquidity when another fund was under pressure and then rapidly reduce Citadel’s exposure.

Taken together, experts say, the moves paint a picture of a hedge fund manager willing to buy when others are forced to sell, take profits when opportunities change and rotate capital toward companies with strong underlying businesses.

Read more Miami billionaire Ken Griffin is making big moves on Wall Street. What’s he buying?

This story was originally published August 28, 2026 at 5:00 AM.