IRON shorts rebuild ahead of June earnings

Disc Medicine heads into its June 18 earnings report with short sellers quietly adding exposure and the ORTEX short score at a fresh weekly high.

Short interest is the dominant story here. Bears have rebuilt their position to 15.6% of the free float — a level that places IRON firmly in the top tier of shorted biotech names. The move has been steady rather than dramatic: shorts added roughly 8% in a single day on June 9 and are up nearly 6% on the week, extending a 12% build over the past month. The ORTEX short score reached 74.4 on June 9, the highest reading in the recent ten-session window, reinforcing the picture of growing bearish conviction heading into the print. Days-to-cover from the official FINRA settlement stands at 14.6 — meaning a meaningful reversal in sentiment would take nearly three weeks to unwind at average volumes, a dynamic that cuts both ways.

The borrow market tells a subtler story, and it's worth naming the contrast. Despite the position build, the lending environment remains comfortable. Availability runs at 242% — more than two shares available to borrow for every one already shorted — well above the 52-week low of 181% reached in early May. Cost to borrow is just 0.53%, essentially unchanged over the past month. Bears can add to shorts cheaply and without constraint, which means the short interest increase reflects genuine directional conviction rather than a forced or squeezed dynamic.

Options traders are conspicuously unbothered. The put/call ratio of 0.20 is in line with its 20-day average and barely a quarter of a standard deviation above the mean — call positioning still dominates the options book by a wide margin. That PCR reading is a long way from the 52-week high of 2.61, suggesting the broader options market is not hedging into the event. The disconnect between a rising short book and a still call-heavy options tape is the week's central tension.

The Street remains broadly constructive, though targets have drifted lower from peaks set in late 2025. Wedbush reiterated Outperform with an $88 target on June 10. Morgan Stanley raised its target to $80 from $75 in mid-May while holding Overweight. The consensus mean target is around $101, implying roughly 48% upside from the $68.34 close — a gap that reflects either genuine pipeline optionality or stale optimism depending on your view. The bull case centres on bitopertin's FDA approval trajectory and early Phase 2 data for DISC-0974 in myelofibrosis-related anemia. Bears point to the modest commercial ceiling for erythropoietic protoporphyria, a limited cash runway, and the binary nature of the upcoming readout. The short score ranking in the 8th percentile and a days-to-cover ranking also in the 8th percentile signal that the data is flagging IRON as a name where short-side risk is above average relative to the broader universe.

Among close peers this week, TVTX gained 13% and ARQT rose nearly 10%, while ALT fell 8% — a divergent backdrop that offers no clean directional read for the group. IRON itself added just 0.5% on the week, flat relative to the broader biotech move, even as short positions climbed.

Institutional holders are not obviously reducing exposure. FMR (Fidelity) holds 14.6% of shares and added 586,000 shares in Q1. RA Capital, a specialist healthcare fund, added 474,000 shares over the same period to reach 6.4%. State Street added 510,000 shares through April. The insider register is less encouraging: the CFO and Chief Medical Officer both sold stock in April at prices close to current levels, though transaction sizes were modest and significance scores were low.

What to watch into June 18 is whether the short build accelerates further in the final sessions before the print — a continuation at the current pace would push short interest meaningfully above 16% of float — and whether the call-heavy options positioning begins to unwind if trial-outcome uncertainty sharpens.