01—Abstract
Summary
Summary of the 8-K filed September 10, 2025. Cited figures are marked; the original filing is the authoritative source.
On September 8, 2025, Alnylam Pharmaceuticals announced a proposed private offering of $500 milliona of convertible senior notes due 2028 under Rule 144A, and on September 9, 2025 it priced an upsized $575 million offering of 0.00% convertible senior notes due September 15, 2028, with a 13-day option for initial purchasers to buy up to an additional $86.25 million.
The notes carry no regular interest and do not accrete, and the initial conversion price is approximately $670.11b per share, a roughly 40% premium to the $478.6327 VWAP on September 9, 2025. Net proceeds are estimated at about $561.6 million, or about $645.9 million if the option is exercised in full. The offering is expected to close September 12, 2025.
A central feature of the transaction is the use of proceeds: Alnylam is using approximately $30.7 millionc to fund capped call transactions (cap price of about $837.61 per share, a 75% premium to the reference VWAP) and is applying the remainder, together with cash on hand, to repurchase about $637.8 million of its 1.00% convertible senior notes due 2027 for a total cost of about $1,105.8 million including accrued interest. Those repurchases were negotiated with certain existing noteholders, and hedged holders are expected to unwind equity hedges by buying common stock or entering into derivative transactions, which could push the share price up and raise the effective conversion price of the new notes.
For investors, the transaction swaps expensive 1.00%d debt maturing in 2027 for zero-coupon debt maturing in 2028 with a lower cash interest burden, while adding dilution protection through the capped calls and a meaningful conversion premium. Investors should weigh the potential dilution if the notes convert, the cash cost of the repurchase and capped calls, the 2028 maturity and redemption features, and the near-term share price effects from hedging activity, as described in the filing.
02—Key points
Key Highlights
- Upsized private offering of $575 million of 0.00% convertible senior notes due September 15, 2028, up from the $500 million initially proposed on September 8, 2025.
- Initial conversion price of approximately $670.11 per share, a roughly 40% premium to the $478.6327 VWAP on September 9, 2025 (conversion rate of 1.4923 shares per $1,000 principal).
- Estimated net proceeds of about $561.6 million, or about $645.9 million if the initial purchasers exercise their $86.25 million option in full.
- Approximately $637.8 million of 1.00% convertible senior notes due 2027 to be repurchased for about $1,105.8 million including accrued interest, funded by note proceeds and cash on hand.
- Capped call transactions costing about $30.7 million, with a cap price of approximately $837.61 per share (a 75% premium to the reference VWAP) to mitigate dilution.
- Hedging activity by option counterparties and hedged noteholders could affect Alnylam's share price around pricing and in later periods, potentially raising the effective conversion price.
- Notes are unsecured senior obligations, redeemable for cash on or after September 20, 2027 if the stock trades at or above 130% of the conversion price for a specified period.
03—Questions
Frequently Asked Questions
What is the size and terms of the convertible notes Alnylam priced?
Alnylam priced an upsized $575 million offering of 0.00% convertible senior notes due September 15, 2028. The notes are senior unsecured obligations that do not bear regular interest and do not accrete. Holders can convert before June 15, 2028 only in certain circumstances, and freely from June 15, 2028 until the second trading day before maturity. Alnylam may settle conversions in cash, shares, or a combination.
What is the conversion price and how does it compare to the recent stock price?
The initial conversion rate is 1.4923 shares per $1,000 principal, equal to an initial conversion price of about $670.11 per share. This is roughly a 40% premium to the $478.6327 VWAP on September 9, 2025, the reference price used for pricing.
Why is Alnylam repurchasing its 2027 convertible notes?
Alnylam is using the proceeds, together with cash on hand, to repurchase about $637.8 million of its 1.00% convertible senior notes due 2027 for about $1,105.8 million including accrued interest. The repurchases were negotiated privately with certain existing noteholders. This replaces higher-coupon debt with the new zero-coupon notes, which lowers near-term cash interest obligations.
What are the capped call transactions and how do they limit dilution?
Alnylam used about $30.7 million of proceeds to enter into capped call transactions with option counterparties. They are expected to reduce dilution when notes convert and/or offset cash payments above principal, subject to a cap. The initial cap price is about $837.61 per share, a 75% premium to the reference VWAP, so dilution protection applies only between the conversion price and the cap.
What risks could the offering create for existing shareholders?
If the notes convert into shares, existing shareholders could be diluted, although the capped calls are intended to offset part of this. Hedging by option counterparties and by noteholders unwinding equity hedges could push the share price up or down around pricing and during conversion observation periods, which could raise the effective conversion price. The offering was also subject to market conditions and was not guaranteed to close on the stated terms.
04—Continue