Merck and Moderna maintain a decade-long collaboration focused on mRNA cancer vaccines, including the recently successful Phase 3 melanoma trial for intismeran in combination with Keytruda, which has boosted Moderna’s valuation without altering ownership structures. Merck has pursued separate oncology bolt-ons such as the $6.7 billion Terns Pharmaceuticals deal, while Moderna navigates independent challenges including an FDA refusal-to-file on its flu vaccine candidate. These dynamics reinforce trader consensus around a low probability of a full merger or acquisition announcement this year, as both firms prioritize targeted partnerships and pipeline execution over consolidation. A sudden shift could arise from unexpected capital needs or strategic realignment, though current trajectories show no such catalysts.