Magnetar Financial LLC 4

What Happened
Magnetar Financial LLC (acting for multiple Magnetar funds and a 10% owner) reported that multiple short derivative positions tied to CoreWeave Class A common stock expired unexercised on June 18, 2026. The filing lists a total of 3,000,000 shares worth $0 disposed via expiration (transaction code "E"). These derivatives were part of a collar entered on September 10, 2025; both the call and put expired for no value because CoreWeave's closing price on June 18 was between the call and put strike prices. No underlying shares were transferred and no cash changed hands as a result.

Key Details

• Transaction date: 2026-06-18; filing date (Form 4): 2026-06-23.
• Total derivative shares expired: 3,000,000; reported value: $0 (expired unexercised).
• Transaction code: E (expiration of short derivative position). Footnote F1 explains the collar arrangement and why options expired worthless. Footnotes F10–F16 identify which Magnetar funds directly held the reported securities.
• Role/ownership: Magnetar Financial is an investment adviser to multiple Magnetar funds (F2); Magnetar Capital Partners and related entities are disclosed in F3–F4. These are institutional holdings (10% owner), not individual executive trades.
• Shares owned after transaction: not specified in the provided excerpt.
• Filing timeliness: filed 6/23/2026 for a 6/18/2026 transaction; no late-filing flag was provided in the supplied data.

Context
This was an expiration of option contracts (a collar), not a market sale or purchase of CoreWeave shares. When collars expire unexercised, there is no transfer of the underlying stock and no proceeds; such expirations are typically informational. Because Magnetar is reported as a 10% owner through multiple funds, this filing reflects institutional derivative activity rather than a personal insider buy/sell.