Merck & Co. Inc. (NYSE:MRK)

The common-size income statement reveals significant fluctuations in profitability and expense management over the five-year period. Sales remained consistently at 100% throughout, providing a stable base for analysis. However, substantial shifts are observed in the composition of revenues and expenses.

Gross Profit

Gross profit as a percentage of sales demonstrates volatility, beginning at 72.02% in 2021, decreasing to 70.63% in 2022, then increasing to 73.17% in 2023, peaking at 76.32% in 2024, and slightly declining to 74.80% in 2025. This suggests varying levels of efficiency in managing the cost of sales, with improvements in 2023 and 2024.

Operating Expenses

Selling, general and administrative expenses decreased from 19.78% of sales in 2021 to 16.51% in 2025, indicating improved control over these costs. However, research and development expenses experienced a dramatic increase in 2023, reaching 50.79% of sales, before decreasing to 24.29% in 2025. This suggests a significant, potentially one-time, investment in research and development in 2023. Restructuring costs remained relatively stable, fluctuating between 0.48% and 1.37% of sales.

Operating Income

Operating income exhibited considerable variation. It began at 25.74% of sales in 2021, rose to 30.27% in 2022, plummeted to 3.92% in 2023 (likely due to the increased R&D spending), and then rebounded strongly to 31.03% in 2024 and 32.64% in 2025. This highlights the impact of research and development investments on short-term profitability.

Non-Operating Items

Interest income and expense remained relatively consistent as percentages of sales, with interest expense slightly increasing over time. Exchange losses fluctuated, decreasing from 0.61% to 0.35% before rising again to 0.50%. Income from investments in equity securities showed significant volatility, including a negative impact in 2022. Net periodic defined benefit plan credit increased from 0.44% to 0.99% before decreasing slightly to 0.95%. Other income (expense), net, was also volatile, shifting from positive to negative values.

Net Income

Net income followed a similar pattern to operating income, starting at 26.82% of sales in 2021, decreasing to 24.50% in 2022, falling sharply to 0.63% in 2023, and then recovering to 26.70% in 2024 and 28.09% in 2025. The significant decline in 2023 aligns with the substantial increase in research and development expenses. Income from discontinued operations contributed 1.45% to net income in 2021, with no contribution in subsequent years. Net income attributable to Merck & Co., Inc. mirrored the overall net income trend.

Overall, the financial performance demonstrates a cyclical pattern, heavily influenced by strategic investments in research and development. While these investments negatively impacted profitability in 2023, they appear to have contributed to improved operating income and net income in 2024 and 2025. The company also appears to have successfully managed selling, general and administrative expenses over the period.