Alnylam Pharmaceuticals has become a candidate for inclusion in the S&P 500 index, a development driven by its transition to sustained profitability under standard accounting rules. The biotechnology company, which utilizes RNA interference to switch off genes responsible for certain diseases, now holds a market capitalization of approximately $31 billion. This financial status distinguishes it from most drugmakers, which are typically excluded from the index until their products achieve sufficient scale. Consequently, Alnylam carries a trailing price-to-earnings ratio of nearly 44 times, while its forward multiple stands at 20 as earnings growth integrates into its valuation.
The primary argument for Alnylam's inclusion rests on the rapid expansion of its drug franchise, led by AMVUTTRA. In the second quarter, revenue surged by roughly 74% to $1.2 billion, marking a record performance for the company. The drug's approval for treating ATTR cardiomyopathy, a common heart condition, serves as the main growth engine by opening a significantly larger market than its original use in rare diseases. Behind this flagship product lies a pipeline of other RNA-based treatments intended to provide ongoing profit boosts. For an index committee that has added few healthcare names recently, Alnylam represents an appealing option to rebalance the sector mix.
Conversely, skeptics point to the stock's volatility and recent guidance adjustments. The share price has round-tripped, falling from a high near $495 to approximately $233 amid questions regarding competition and the durability of growth. Management recently trimmed full-year product revenue guidance to a range of $4.7 billion to $5.1 billion, citing the normalization of second-line demand for AMVUTTRA following an unusually strong initial launch phase. With biotech earnings often fluctuating quarter to quarter, the stock's premium valuation depends heavily on continued strong execution. A single soft quarter could negatively impact both the company's young reported profits and its high multiple.
Recent market performance has been mixed for investors holding the stock. Over the past six months, Alnylam shares slid by 25.5%, while the Insider Monkey Billionaire Index gained 11.6% during the same period. Despite the price decline, institutional interest appears to be strengthening. According to Insider Monkey's database, ownership of Alnylam increased to 64 hedge funds at the end of the second quarter of 2026, up from 54 in the previous quarter.
The central question for potential index inclusion is whether Alnylam's newly achieved earnings are steady enough to consistently clear the profit test required for S&P 500 membership. While the healthcare sector's thin representation among recent additions may aid its case, investors must weigh the room for growth after the recent pullback against AMVUTTRA's potential to compound value in the face of new competition.