The primary driver behind the downward movement and intraday volatility in Pfizer’s stock is the recent major clinical setback in its oncology pipeline. The company reported disappointing topline Phase 3 results for its investigational antibody-drug conjugate, sigvotatug vedotin, in patients with advanced non-squamous non-small cell lung cancer. The trial failed to meet its primary overall survival endpoint compared to standard chemotherapy. Because this candidate was a cornerstone asset from Pfizer’s massive forty-three billion dollar acquisition of Seagen, the trial failure represents a significant blow to the company’s long-term oncology strategy, raising questions about the return on its heavy biotechnology investments and…