RGEN Heads Into Second Print With Shorts Still Holding

Repligen Corporation reports again today — a second earnings event in quick succession — with shorts bruised but not broken after the July 28 squeeze, and options traders still running unusually defensive positioning.

Short interest has barely moved since the 11% post-earnings rally flagged in the prior note. The short book eased only modestly to 10.9% of the free float, down less than 1% over the week, suggesting the covering wave was shallow. That residual position matters: with roughly 6.1 million shares still short and days-to-cover near eight by the official FINRA count, another sharp upside print could force a more complete unwind. The borrow market has tightened further since then — availability has compressed from 353% a week ago to 298% now, the sharpest weekly contraction in the recent window — though at nearly three shares available for every one borrowed, the lending pool remains comfortably stocked. Cost to borrow is still just 0.57%, up about 10% over the week, a directional nudge rather than a distress signal.

Options positioning remains the loudest read in the room. The put/call ratio is running at 2.60, still nearly 2.6 standard deviations above its 20-day average of 1.88 — elevated even after pulling back slightly from the 2.68 reading seen on July 28. That level of put-heavy positioning, so soon after a significant post-earnings pop, points to investors buying protection against a giveback rather than adding fresh directional exposure.

The analyst community has grown incrementally more constructive. JP Morgan raised its target to $175 from $165 on July 29 while holding Overweight — the most recent bellwether move, and one that came with the print effectively in hand. That sits below the consensus mean of $185, itself about 31% above the current price of $141. The bull case rests on the guidance raise to $715–735M in full-year revenue, with CDMO and biopharma channel growth running above 20% year-on-year and Process Analytics revenues up more than 50%. Bears focus on the margin story: adjusted operating margin guidance was cut to roughly 13.5% and EPS guidance of $1.65–$1.68 leaves limited room for execution error. T. Rowe Price, the largest reported holder at just over 11% of shares, added nearly one million shares in the last reported quarter — a vote of confidence that bulls will cite, though the data reflects positioning before either of the two most recent earnings events.

Today's print is therefore less a test of whether Repligen is growing and more a question of whether the margin trajectory can stabilise — and whether a short book that survived the first squeeze is willing to wait for an answer.