Alnylam Pharmaceuticals’ stock declined after the company revealed mixed results from the HELIOS-B trial for its investigational RNAi treatment, Amvuttra. While the study met its primary endpoint of reducing mortality and cardiovascular events, the reduction in mortality was not statistically significant, potentially impacting investor sentiment. Despite the setback, Amvuttra remains a key revenue driver for Alnylam and is expected to become a standard treatment for ATTR amyloidosis with cardiomyopathy.