In Q1'26, Pfizer's total operating expenses reached $5.59B USD, comprising $2.63B in R&D expenses and $2.96B in SG&A expenses, reflecting a modest quarterly increase from Q4'25's $7.37B total driven by seasonal factors in R&D investments. Over the period from Q2'23 to Q1'26, total operating expenses exhibited volatility with an overall upward trend, peaking at $7.37B in Q4'25 due to elevated SG&A costs averaging $4.16B annually, while R&D expenses fluctuated between $2.2B and $3.21B, showing a 10% growth from Q2'23's $6.15B baseline; notable spikes occurred in Q4 quarters, likely tied to year-end accruals, underscoring a pattern of higher administrative burdens offsetting stable research spending.