Magnetar Trims CoreWeave Stake 8.4%, Keeps $4.15 Billion Bet

Magnetar Financial cut its CoreWeave stake by 8.4% in the third quarter, holding 47,686,666 class A shares worth $4.15 billion at Sept. 30, according to a 13F filed Friday, Nov. 13. The AI cloud provider still represented about 40.7% of the $10.22 billion in US-listed securities the Evanston, Illinois hedge fund reported.

The share count fell by 4,376,261, from 52,062,927 at June 30. The position's value dropped $1.03 billion, from $5.18 billion three months earlier, according to the filing. CoreWeave's weight in the reported book declined from about 47.3% of $10.96 billion at the end of the second quarter.

What drove the $1.03 billion value drop?

The filing's implied prices show the answer. The math works out to about $99.49 per CoreWeave share at June 30 and $87.12 at Sept. 30. Most of the value decline came from the falling share price, not the sale itself. The 13F shows no CoreWeave options.

CoreWeave class A	June 30	Sept. 30
Shares	52,062,927	47,686,666
Value	$5.18B	$4.15B
Share of reported book	47.3%	40.7%

CoreWeave shares have moved sharply since the quarter closed. The stock jumped 25% on Nov. 11 after the company reported third-quarter results.

Magnetar's total reported holdings fell to $10.22 billion from $10.96 billion. The number of table entries rose to 2,132 from 1,713, indicating a broader spread of positions.

The relationship between the two firms predates CoreWeave's AI cloud business. Magnetar's tie began with a $50 million loan in 2021, when CoreWeave was still a crypto-mining operation, Hedgeweek reported. That early exposure helped make Magnetar one of CoreWeave's largest shareholders.

How did the rest of the AI book change?

Most of Magnetar's other AI-related lines are hybrid securities of the kind convertible-arbitrage funds trade, not common stock. The adjustments in the quarter were:

• Alphabet: cut class A depositary preferred shares, each representing one-twentieth of a preferred share, to 328,617 from 1,496,367; added a new class B series of 742,750.
• Oracle: reduced 6.5% Series D depositary preferred to 175,420 from 1,425,420.
• Hewlett Packard Enterprise: cut 7.625% mandatory convertible preferred to 350,010 from 760,010.
• Super Micro Computer: raised 7% depositary preferred to 720,680 from 570,680.

The moves show rotation within the AI and cloud-computing supply chain rather than a broad retreat. Magnetar reduced preferred exposure to Oracle and HPE while adding to Alphabet's new series and Super Micro.

Where is the fund adding?

Utilities connected to power demand grew. Magnetar roughly doubled its NextEra Energy equity units due in 2029, to 1,119,154 from 550,000. It opened a new position of 1,160,000 Duke Energy equity units worth $55.8 million.

Exits included DigitalBridge common stock, 4.12 million shares worth $65.0 million at June 30. The fund also sold out of SkyWater Technology, 1.18 million shares, and Chart Industries. It dropped convertible notes of GameStop and PG&E.

What can a 13F actually tell investors?

A 13F lists only long positions in US-listed securities at quarter end. It does not show short sales, hedges or private holdings. The filing therefore cannot say whether these lines are directional bets or one leg of a hedged trade.

Magnetar's private activity sits outside the document. The firm led a $500 million round in data-center developer Torus this week, a deal that does not appear in the filing.

The filing shows a fund that trimmed its single largest AI position while spreading capital across more lines, and the Nov. 11 rally means the remaining CoreWeave stake is likely worth more today than its Sept. 30 mark suggests.