When billionaire Ken Griffin pours billions into a stock, investors pay attention.
Griffin’s Citadel added approximately $2.52 billion worth of Amazon (AMZN) stock, taking its position to more than $3.2 billion, per its latest 13F filing. The hedge fund also doubled its stake in AI bellwether Nvidia (NVDA), cementing a position that’s worth nearly $4 billion.
The massive bets clearly point to Griffin wanting more exposure to the relentless AI arms race.
Amazon stock has wobbled of late, on the back of its aggressive $200 billion capital spending plan linked to AI.
For perspective, the stock is down 11.3% year to date, and more than 14% in the past month. However, from a fundamental standpoint, Amazon continues to impress, spearheaded by a healthy AI-powered backlog and its robust cloud sales.
Even with investors getting spooked about AI, the data still point to healthy demand that remains as solid as ever.
For perspective, Ray Dalio’s Bridgewater also piled into Nvidia, a massive $253 million bet, adding roughly 1.35 million shares, which took its total stake to nearly $721 million at year-end.
On top of that, billionaire investor David Tepper has been shopping in tech, with Appaloosa putting millions to work in Micron, Google, and Meta Platforms.
Griffin remains unfazed by the volatility in tech and is positioning Citadel for what this year could look like if AI spending effectively turns from promise into profits.
Ken Griffin’s Citadel disclosed a multibillion-dollar addition of Amazon stock.
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Citadel portfolio 13F activity breakdown
- Market value: $0.67 trillion (prior $0.66 trillion)
- Inflows/(outflows) as % of total MV: +0.52%
- New purchases: 2,088 stocks
- Added to: 5,010 stocks
- Sold out of: 2,204 stocks
- Reduced holdings in: 5,384 stocks
- Top 10 holdings concentration: 22.8%
- Turnover: 29.2% Source: WhaleWisdom
Who is Ken Griffin?
Ken Griffin is considered one of the most prolific investors of the past five decades, having grown Citadel into a global hedge fund juggernaut.
Things started off modestly for Griffin, trading from his Harvard dorm room back in the mid-1980s and applying quantitative models to guide his bets.
He later launched his first fund in 1987 and efficiently navigated the “Black Monday” crash with considerable aplomb through well-timed short positions.
More Fund Managers:
- Ray Dalio’s Bridgewater invests $253 million in major AI stock
- JPMorgan builds $2.93 billion stake in health care stock
- Jim Simons’ Renaissance drops $520 million on surging tech stock
Griffin officially founded Citadel in the 1990s and grew its presence across stocks, fixed income, and commodities, quickly turning the hedge fund into a dominant market-leading operation.
Citadel has also consistently shared its success with clients when performance is strong, rather than simply allowing the fund to swell in size.
For perspective, in December 2025, reports showed that Citadel effectively planned to return nearly $5 billion of 2025 profits to its investors in early 2026, Investing.com reported. With that payout cleared, the firm was expected to begin 2026 with nearly $67 billion in assets under management, down from $72 billion before the distribution.
Moreover, at a personal level, Griffin consistently ranks among the richest individuals on Wall Street, boasting a net worth of nearly $49.6 billion, according to Forbes.
Citadel’s biggest 13F swings
Top buys (largest value)
- Netflix (put options): $3.44 billion
- Tesla (call options): $3.15 billion
- Amazon: $2.52 billion
- Nvidia: $2.19 billion
- Meta Platforms (call options): $2.16 billion Source: WhaleWisdom
Top sells (largest value)
- SPDR S&P 500 ETF (put options): $8.21 billion
- Invesco QQQ Trust (put options): $4.95 billion
- Invesco QQQ Trust (call options): $2.88 billion
- Nvidia (put options): $1.89 billion
- SPDR Gold Shares (call options): $1.38 billion Source: WhaleWisdom
Top holdings (percent of portfolio)
- Invesco QQQ Trust (put options): 3.34%
- SPDR S&P 500 ETF (put options): 2.97%
- Tesla (call options): 2.95%
- SPDR S&P 500 ETF (call options): 2.74%
- Nvidia (call options): 2.18% Source: WhaleWisdom
Betting billions on the AI buildout
Citadel’s $2.52 billion Amazon buy feels like a conviction move as the stock struggles to impress Mr. Market.
Amazon stock took a big hit following its most recent earnings report, which prompted investors to fixate on a single eye-popping $200 billion capex number. Of late, investors are in “show me” mode with AI, putting Amazon and other tech players under duress.
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However, Griffin’s looking at the bigger picture with Amazon continuing to impress on the fundamentals side.
Amazon posted a whopping $716.9 billion in 2025 net sales, up 12%, with $80 billion in operating income. Its cloud service in AWS alone is delivering a tremendous $128.7 billion in revenue, surging 20%, with an eye-catching $45.6 billion in operating income to boot.
Amazon’s free cash flow has tightened as well, hovering at around $11 billion, but with AWS’s backlog at around $244 billion, it’s clear that demand is still there.
And Amazon wasn’t the only major mega-cap AI stock Griffin leaned into.
Citadel also expanded its Nvidia position by a sizeable margin, now worth nearly $4 billion, even with the stock facing weakness.
In a recent piece, TheStreet tech expert Vuk Zdinjak notes that Bank of America remains bullish on Nvidia stock, reiterating a buy rating and a $275 price target.
BofA’s Vivek Arya argues that despite the stock’s recent wobbles, Nvidia remains at the heart of the hyperscaler spending boom, lifting AI data-center addressable market estimates to a whopping $1.4 trillion by 2030.