Alnylam Pharmaceuticals enters the week with its most bullish options configuration of the past year, even as the short-side rebuild that defined early June quietly goes into reverse.
The standout this week is in the options market. The put/call ratio has collapsed to 0.35 — the lowest reading in the past 52 weeks, against a 52-week high of 1.22 — and sits nearly 3.6 standard deviations below its 20-day average of 0.44. That's not a drift toward bullishness; it's a sharp rotation into call-side positioning. The move happened fast: just one week ago the PCR was running above 0.41, in line with its recent range. Whatever is driving the call demand, it arrived this week.
Short interest tells a different story — a moderating one. The rebuild that was the dominant narrative in the prior note has stalled and partially reversed. Short interest fell 2% on the week to 4.05% of the free float, or roughly 5.35 million shares, unwinding about half the late-May step-up. A week ago this column was tracking a deliberate 14% rebuild; that conviction appears to have faded. Borrowing costs remain negligible at 0.41% annualised, and availability is extraordinarily loose at over 6,000% of current short interest — meaning for every share currently borrowed short, roughly 60 more are available in the lending pool. There is no mechanical squeeze dynamic, and the short score has drifted gently lower all week, from 40.0 to 39.4, consistent with the reduction in borrowed shares.
The Street remains firmly in the bull camp, though the gap between consensus and price continues to draw attention. The mean analyst target is $441, implying roughly 48% upside from the current $297.69. Bulls point to the RNAi platform's commercial momentum — particularly global uptake of the existing portfolio — and a pipeline that includes potential launches in polyneuropathy by 2028 and cardiomyopathy by 2030, plus proof-of-concept data expected in the second half of 2026 for ALN-6400. Citigroup initiated with a Buy and a $380 target in mid-May, adding fresh institutional sponsorship. The bears counter with pricing pressure risk on key products, late-stage safety uncertainty, and the ever-present competition and IP exposure that shadows any platform biotech. Valuation is not cheap: EV/EBITDA runs at 26x and price-to-book at 13x, both edging higher over the past month. The analyst recommendation divergence factor scores in the 97th percentile across the universe — an unusually wide spread of views for a single name.
Institutional ownership adds a layer of conviction to the bull case. Capital Research and Management holds 15.3% of shares — a concentrated position for a passive or semi-active manager — and added 1.5 million shares in the most recently reported period. FMR and BlackRock each hold over 7%, with both adding modestly. T. Rowe Price holds nearly 5% and added 3.2 million shares as of end-March, one of the more aggressive additions in the register. On the insider side, director David Pyott sold roughly $1.1 million in shares on June 1 across several small tranches — low-significance transactions individually, though the cluster on a single date is worth noting. Net insider activity over 90 days is a modest positive at $3.5 million in net value, but driven more by the absence of large sales than by active buying.
The next scheduled catalyst is Q2 earnings on August 6. The prior three prints produced modest reactions: a 2.1% gain on May 20, a 2.6% decline on May 7, and a 1.7% decline at the April print — tight moves for a biotech, suggesting the market is valuing the commercial story on steady execution rather than binary trial readouts. The sharper call-side rotation this week, combined with the easing of short positions and the looming second-half data readouts, makes the options skew the number to watch in the sessions ahead.
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