JWCA advises Alnylam Pharmaceuticals on its upsized $575 million convertible and capped call transaction to retire a portion of its outstanding convertible notes

September 2025 | read press release

Transaction Background

Alnylam Pharmaceuticals, Inc. (“Alnylam” or “the Company”) successfully raised an upsized $575mm (before greenshoe) in the convertible market at very attractive terms (0.00% coupon and 40.0% conversion premium), while retiring ~$638mm (~62%) of its outstanding 2027 convertible notes

Alnylam’s objectives included:

  • Opportunistically retire 2027 convertible notes ahead of maturity to manage outstanding liabilities and equity dilution

  • Protect against future equity dilution through a derivative overlay

  • Minimize stock price risk during execution after reaching an all-time high stock price in the weeks leading up to execution

JWCA provided extensive analysis on deal structuring and related items, including:

  • Long-term capital structure strategy

  • Refinancing tactics and analysis

  • Convertible and derivative overlay structuring

  • Syndicate structure and precedent data

  • Execution timing

  • Shareholder messaging

JWCA designed and ran a capped call auction process to achieve competitive terms

JWCA provided advice, support and analysis throughout the execution process

Results

Alnylam’s convertible transaction was very well received by investors:

  • The transaction was multiple times oversubscribed leading to the issue being upsized by $75mm (15% of original $500mm base deal)

  • The 0.00% coupon was the low end of the marketed range and the 40.0% conversion premium was higher than the high end of the marketed range, making it the best-priced health care convertible since 2021

The Company retired ~$638mm of outstanding 2027 convertible notes at a minimal premium to market price

Capped call documentation and auction process produced meaningful savings for Alnylam, driving economics in the Company's favor