In Q4'25, Pfizer's (PFE) operating expenses reached a peak of $7.37B, driven by R&D expenses of $3.21B and SG&A expenses of $4.16B, marking the highest quarterly total in the observed period from Q1'23 to Q4'25. Over the three-year timeframe, total operating expenses exhibited volatility with an overall upward trajectory, rising from $5.92B in Q1'23 to $7.37B in Q4'25, including notable spikes in Q4'23 ($7.39B) and Q4'24 ($7.31B) primarily due to elevated SG&A costs. R&D expenses showed moderate growth from $2.51B in Q1'23 to $3.21B in Q4'25, with a dip to $2.20B in Q1'25 before recovering, while SG&A expenses fluctuated more significantly, peaking at $4.58B in Q4'23 and demonstrating consistent year-end increases that contributed to the stacked bar chart's expanding pattern.