CoreWeave (CRWV) 10% Holder Magnetar Derivative Positions Expire

What Happened Magnetar Financial LLC — filing as a 10% holder/adviser to multiple Magnetar funds — reported that a series of short derivative positions (call and put options entered as a collar) expired unexercised on September 18, 2026. The filing shows 6,000,000 derivative share-equivalents disposed via expiration, with no cash exchanged (aggregate value $0). These were expirations of options (transaction code "E"), not open-market sales of CoreWeave common stock.

Key Details

• Transaction date: 2026-09-18; transaction code: E (expiration of short derivative position).
• Total derivative shares disposed: 6,000,000; reported dollar value: $0 (options expired worthless).
• Instrument & reason: A call and a put entered Aug 18, 2025 as part of a collar expired unexercised because CRWV's closing price on 9/18/2026 was between the strike prices (see footnote F1).
• Holdings: The expired positions were held across multiple Magnetar funds (see footnotes F10–F15); Magnetar Financial is the adviser (F2). The filing includes standard disclaimers of beneficial ownership by related entities (F3–F4).
• Shares owned after transaction: not specified in this Form 4.
• Filing timeliness: Reported and filed on 2026-09-18 (same day), so appears timely.

Context A collar involves selling a call and buying a put (or similar paired positions) to hedge exposure; when both options expire unexercised and for no value, the derivative positions simply lapse and no stock changes hands. For retail investors, note this is an institutional hedging/derivative outcome from a 10% holder — not a straightforward insider sale or purchase of CoreWeave shares. Derivative expirations at $0 do not necessarily signal a buy or sell opinion on the underlying stock.