Moderna (NASDAQ:MRNA) stock fell 7% to $148.02 midday Wednesday, giving back a large portion of Tuesday's 14% rally that followed Wolfe Research's upgrade to Peer Perform from Underperform. BioNTech SE (NASDAQ:BNTX) stock also declined 2% to $111.60, suggesting the selloff is largely Moderna-specific. No fresh company news was available to explain Moderna's slide, which appears to be profit-taking after a significant year-to-date surge.