Inhibrx Biosciences has put in one of biotech's more dramatic single-month moves — up 45% to $121.17 — yet short sellers haven't flinched, and two company insiders remain on the SEC's activist register with Schedule 13D filings still outstanding.
The short position is the defining tension here. At 22.1% of the free float, roughly 3.2 million shares are still sold short — and that number has barely moved in five weeks. The latest FINRA fortnightly settlement date (August 14) showed 3.2 million shares short with days-to-cover running at 14.4 days, a notably long unwind period. Shorts have trimmed modestly from 3.43 million shares in late July — a roughly 6% reduction over the month — but have not accelerated their exit into the rally. That's the contrast worth noting: a stock up 45% in a month with a short base that refuses to capitulate.
The borrow market, however, does not reinforce that bearish conviction. Availability is loose — 435% relative to current short interest — meaning there are roughly four shares available to borrow for every one already lent out. Cost to borrow has drifted lower, running near 0.49% from around 0.66% at the August 28 peak. With supply ample and borrowing cheap, there is no mechanical squeeze pressure building in the lending pool right now. The ORTEX short score, at 70.2, sits in elevated territory but has eased marginally from 71.2 in late August — a slight softening in the overall short-side signal. Options traders are not adding urgency either: the put/call ratio of 0.21 is barely above its 20-day average and roughly half a standard deviation from normal, pointing to a market that is neither hedging aggressively nor speculating heavily to the upside.
The Street is cautiously constructive, though the coverage universe is thin. HC Wainwright initiated on August 24 with a Buy and a $245 target — the most recent and relevant action — joining Stifel's April initiation at $150 (now well inside the current price). The consensus mean target of $267 sits well above the current $121, implying the Street thinks the stock has further to run even after the July-August surge. The bull case centres on ozekibart's Phase 3 progress in advanced chondrosarcoma and INBRX-106's potential in combination head-and-neck cancer regimens. The bear case is straightforward: a negative earnings yield (-0.07), a P/E of -13.9, and an Altman Z-score that signals financial stress. The analyst recommendation differential factor score ranks in the 93rd percentile of the universe — a sign the few analysts covering INBX are meaningfully more positive than the average stock — but quality metrics remain stressed.
The ownership picture adds another layer. Two insiders — founder Mark Lappe (6.4% as last disclosed) and director Jon Faiz Kayyem (7.9%) — both carry Schedule 13D/A filings from February 2026, which denotes activist intent rather than passive holding. Both positions have been static since that filing date; neither has reported a change. As always with 13D registrations, stakes reflect the position as last disclosed around the 5% threshold, and a holder falling below 5% is not obliged to file again. Viking Global, the largest institutional holder at 9.4%, trimmed 78,000 shares in Q2 and was a large open-market seller in October 2025 at $32 — a price that in retrospect looks prescient given the subsequent rally. Schonfeld Strategic Advisors added 443,000 shares through Q2, and Bank of America reported a fresh 13G in August, building to 5.7% of shares — a meaningful new entrant at these higher levels.
The next earnings event is flagged for November 13. The recent history on results day is unforgiving: the two most recent scheduled prints delivered -8.9% and -7.9% moves on the day, with further five-day declines of -12.8% and -6.3% respectively. The August 21 update bucked that trend with a 5.8% gain and a 24.5% five-day follow-through — suggesting a clinical or data update rather than a routine financial print. With the stock more than doubling from those October 2025 insider-sale levels, the November print will be the next stress test for a short base that has shown remarkable patience through a 45% rally it has so far declined to exit.
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