The SPCX Greenshoe: How the Underwriters Stabilised the First Week
Inside the 83.3 million-share over-allotment option and how the stabilisation bid shaped SPCX's first-week tape.
Greenshoe size
83,333,333 sh
Cover window
30 days
Stabilisation bid
$135.00
What a greenshoe actually does
The greenshoe — formally the over-allotment option — let the SPCX syndicate sell up to 15% more shares than the headline 555,555,555 figure. Underwriters short that extra block at the offer price. If the stock trades up, they exercise the option to cover; if it trades down, they buy stock in the open market at or above $135 to cover, creating a stabilising bid that defends the offer.
On a deal that opened $15 above the offer, the path of least resistance was full exercise. SPCX never approached the $135 floor in regular trading, so stabilisation never had to fire heavily — but its presence narrowed bid-ask in the opening minutes and kept the tape from gapping down on early flippers.
How to read the first-week tape
Greenshoe exercise notices land via the underwriters' final prospectus supplement and the deal's 8-K. Watch for either 'fully exercised' (bullish — book is clean, syndicate keeps the fees) or 'partial exercise plus syndicate short covered in the open market' (more bullish for short-term tape, as it implies covering bids). Either disclosure typically lands within the first three weeks.
Key takeaways
- The greenshoe upsized the deal to ~638M shares if fully exercised
- Stabilisation gives a soft floor at $135 during the 30-day window
- Full exercise is a green flag — it signals the book held without a defended bid
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