Inhibrx Biosciences heads into its May 15 earnings call sitting on a 70% one-month rally driven by clinical data — yet short sellers remain deeply embedded, setting up one of the more charged setups in small-cap biotech.
The catalyst that lit the fuse came on April 22, when reports surfaced that large drugmakers were circling Inhibrx's cancer pipeline, with deal values cited above $8 billion. The stock was briefly halted on a circuit breaker before closing up more than 55% that day. Then on May 11 — just days before the quarterly print — the company presented interim Phase 2 data for INBRX-106 in combination with Keytruda in first-line head and neck squamous cell carcinoma (HNSCC). Early response rates from the HexAgon study were described as high, adding another layer of momentum into the earnings date. The stock closed at $127.58 on Monday, down 5% on the day — a pullback that arrived even as the clinical news remained constructive, suggesting some profit-taking after a historic move.
Short sellers face a difficult position. Short interest runs at nearly 14% of free float by ORTEX daily estimate, and borrow availability remains loose at roughly 298% of short interest — meaning there is ample capacity in the lending pool and no mechanical squeeze pressure for now. Cost to borrow is modest at under 0.8%, well below the kind of stress levels that typically accompany a forced short unwind. Yet the stock has doubled from where Viking Global Investors sold a combined 350,000 shares in October 2025 at around $32 — a trade that now looks deeply offside. Short interest edged higher through mid-April before retreating slightly in recent sessions, suggesting some covering but no stampede for the exits. The ORTEX short score of 67.7 remains elevated, reflecting the combination of meaningful SI and a still-active borrowing market.
Options traders have turned measurably more cautious into the print. The put/call ratio climbed to 0.31 — more than two standard deviations above its 20-day mean of 0.19 — a level that indicates a clear shift toward hedging activity over the past two weeks. That rotation in the options book is a notable contrast to the otherwise bullish fundamental narrative: M&A speculation, strong Phase 2 readouts, and a stock near its highest levels. The bull case rests on INBRX-106 and INBRX-109 as genuinely differentiated assets with BigPharma acquisition interest. The bear case is structural — INBX burns cash with no commercial revenue, its R&D spend has trailed estimates, and any slip in the regulatory or clinical timeline from here would hit a stock now priced for near-perfection. Stifel initiated coverage with a Buy in early April and a $150 target, which the stock has since blown through, illustrating how quickly the narrative has moved. The consensus mean target of $300 likely reflects an M&A scenario rather than a standalone discounted cash flow — treat it as scenario pricing, not a conventional valuation anchor.
Ownership is concentrated in active managers with conviction-level stakes: Perceptive Advisors holds nearly 10% of shares, Morgan Stanley added over 726,000 shares in Q4, and Sanofi — a potential strategic acquirer — holds a steady 7.9% with no reported change. May 15 will test whether the company's cash position and updated clinical trajectory can hold a stock that has already priced in a great deal of the upside.
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