Shorts have built at massive speed. Short interest went from 23.3M shares at the first print on June 16 to 219.3M on July 29 — reaching 34% of float.

Bigger short than Tesla in dollar terms. SPCX now carries $24.6B of short interest against Tesla's $21B — a book fifteen years in the making.

Pre-IPO investor unlock is the big story. Q2 results land August 4; two days later the first lock-up tranche frees up to 911M shares, more than the current tradeable float.

The SpaceX short book already exceeds Tesla’s. Next comes the Q2 earnings and unlock.

The SpaceX borrow has repriced — 1.37% annualized fee at listing, 0.51% by late June as post-IPO lending supply arrived, now 2–3% on average with new borrows closer to 4%. Utilization sits at 95%. The size is exceptional for a name outside the S&P 500: at a ~1% Nasdaq-100 weight there is limited index or delta-one hedging standing behind $24.6B. This is a directional book, and a meaningful share may be looking to cover into the August 6 unlock.

The current float is 640M shares, 8.5% of shares outstanding. August 6 takes it to ~12%, the December 8 expiry to ~40%, and the June 14, 2027 Musk cliff — 6.4 billion shares landing the same session as a further tranche — to roughly 99%. The balance clears after Q2 2027 results, just over a year out.

There are three key drivers to monitor over the next year. The unlock ladder is the nearest. S&P 500 entry is another — seasoning rules put it out to mid-2027 at the earliest, but the market is already handicapping it. The third is a possible Tesla combination, which would fast-track that inclusion. But first, Q2 earnings Tuesday and the unlock Thursday. S3 provides the positioning and financing data required to trade these events.

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