RBC Capital analyst Kennen MacKay believes RA Pharmaceuticals' (RARX) zilucoplan gMG data "should impress even the skeptics," but he has received questions about why the stock hasn't inflected higher on data that left him "overall highly impressed." He believes the recent run-up of the stock into the data suggests anticipation of a positive result and also thinks the upside has likely been limited by some anticipation for a dilutive financing. Commenting on why the news "isn't more negative" for Alexion (ALXN), MacKay added that he anticipates that Alexion could have strategic interest in an acquisition of RA, with sufficient financial flexibility to pursue a deal, as the latter gets closer to commercialization. MacKay maintains an Outperform rating on RA Pharmaceuticals shares.