Patrick Ryan Investor Contacts: Peter Dannenbaum (973) 275-7075 (908) 740-1037 Michael DeCarbo (908) 740-1807 Merck Announces Fourth-Quarter and Full-Year 2020 Financial

FOR IMMEDIATE RELEASE

Merck Announces Fourth-Quarter and Full-Year 2020 Financial Results

KENILWORTH, N.J., Feb. 4, 2021 - Merck (NYSE: MRK), known as MSD outside the United States and Canada, today announced financial results for the fourth quarter and full year of 2020.

"Despite extraordinary challenges brought on by the COVID-19 pandemic, Merck achieved solid growth and made meaningful progress in our pipeline in 2020. We remain focused on our science-led strategy and are confident that this approach will continue to deliver value to patients and shareholders," said Kenneth C. Frazier, chairman and chief executive officer, Merck. "Our scientists continue to advance our internal pipeline of promising medicines and vaccines, including in oncology, HIV, and pneumococcal disease, and, more recently, therapeutics for COVID-19. These pipeline developments provide us with increasing line-of-sight to significant potential growth drivers later this decade and into the next."

Financial Summary

*Greater than 100%. **Refer to table on page 12.

GAAP (generally accepted accounting principles) (loss) earnings per share assuming dilution (EPS) was $(0.83) for the fourth quarter and $2.78 for the full year of 2020. Non-GAAP EPS was $1.32 for the fourth quarter and $5.94 for the full year of 2020. GAAP EPS for the fourth quarter and full year of 2020 reflect a $2.7 billion charge for the acquisition of VelosBio Inc. (VelosBio). The fourth quarter and full year of 2020 also include a $1.6 billion pretax intangible asset impairment charge related to ZERBAXA (ceftolozane and tazobactam), resulting from a recall in December 2020 and a temporary suspension of sales which reduced expected future cash flows of this product. In addition, the full year of 2020 reflects pretax charges of $1.1 billion related to certain license and collaboration agreements. Non-GAAP EPS excludes the charges noted above, other acquisition- and divestiture-related costs, restructuring costs and certain other items. Refer to the GAAP to non-GAAP reconciliation table on page 12 for further details.

COVID-19 Research Highlights

Building on the company's experience with antivirals, Merck advanced its scientific programs in an effort to help combat SARS-CoV-2, specifically:

1 Net (loss) income attributable to Merck & Co., Inc.

2 Merck is providing certain 2020 and 2019 non-GAAP information that excludes certain items because of the nature of these items and the impact they have on the analysis of underlying business performance and trends. Management believes that providing this information enhances investors' understanding of the company's results and permits investors to understand how management assesses performance. Management uses these measures internally for planning and forecasting purposes and to measure the performance of the company along with other metrics. In addition, senior management's annual compensation is derived in part using non-GAAP pretax income. This information should be considered in addition to, but not as a substitute for or superior to, information prepared in accordance with GAAP. For a description of the items, see Tables 2a and 2b attached to this release.

Oncology Pipeline Highlights

Merck continued to advance the development programs for KEYTRUDA (pembrolizumab), the company's anti-PD-1 therapy; Lynparza (olaparib), a PARP inhibitor being co-developed and co-commercialized with AstraZeneca; and Lenvima (lenvatinib mesylate), an orally available tyrosine kinase inhibitor being co-developed and co-commercialized with Eisai Co., Ltd. (Eisai).

Other Pipeline Highlights

Business Development

Fourth-Quarter and Full-Year Financial Impact of COVID-19

In the fourth quarter, the estimated negative impact of the COVID-19 pandemic to Merck's pharmaceutical revenue was approximately $400 million. As expected, within the company's human health business, revenue was negatively impacted by reduced access to health care providers given social distancing measures, which negatively affected vaccine sales in particular.

Operating expenses were positively impacted in the fourth quarter by approximately $50 million, primarily driven by lower promotional and selling costs, partially offset by higher research and development (R&D) expenses, net of investments in COVID-19-related antiviral and vaccine research programs.

The estimated overall negative impact of the COVID-19 pandemic to Merck's revenue for the full year 2020 was approximately $2.5 billion, largely attributable to the human health business but including approximately $50 million attributable to Animal Health.

Operating expenses for the full year were positively impacted by approximately $600 million, primarily driven by lower promotional and selling costs, as well as lower R&D expenses, net of investments in COVID-19-related antiviral and vaccine research programs.

Fourth-Quarter and Full-Year Revenue Performance

The following table reflects sales of the company's top pharmaceutical products, as well as sales of animal health products.

*Alliance revenue for these products represents Merck's share of profits, which are product sales net of cost of sales and commercialization costs.

**Other revenues are comprised primarily of third-party manufacturing sales and miscellaneous corporate revenues, including revenue hedging activities. The revenue hedging activities resulted in negative revenue in the fourth quarter of 2020.

Pharmaceutical Revenue

Fourth-quarter pharmaceutical sales increased 8% to $11.4 billion. Excluding the favorable effect from foreign exchange, sales grew 6%.The increase was driven by growth in oncology, vaccines, reflecting the replenishment of GARDASIL 9 doses previously borrowed from the U.S. Centers for Disease Control and Prevention (CDC) Pediatric Vaccine Stockpile as discussed below, and hospital acute care, partially offset by the negative impact of the COVID-19 pandemic and the ongoing impacts of the loss of market exclusivity for several products.

Growth in oncology was largely driven by sales of KEYTRUDA, which were $4.0 billion for the quarter. Global sales growth of KEYTRUDA reflects continued strong momentum from the non-small-cell lung cancer indications as well as continued uptake in other indications, including adjuvant melanoma, RCC, bladder, head and neck squamous cell carcinoma (HNSCC) and MSI-H cancers, as well as uptake following the recent launch of the 400mg every 6 week adult dosing regimen in the U.S., partially offset by the negative impacts of the COVID-19 pandemic and pricing in Japan. Also contributing to growth in oncology was higher alliance revenue related to Lynparza and Lenvima reflecting continued uptake in approved indications in the U.S., Europe and China.

Growth in vaccines for the fourth quarter was driven by higher sales of GARDASIL [Human Papillomavirus Quadrivalent (Types 6, 11, 16 and 18) Vaccine, Recombinant] and GARDASIL 9 (Human Papillomavirus 9-valent Vaccine, Recombinant). Fourth-quarter 2020 GARDASIL 9 sales were increased by $120 million due to the replenishment of doses that were borrowed in the fourth quarter of 2019 from the CDC Pediatric Vaccine Stockpile. GARDASIL 9 sales in the fourth quarter of 2019 were decreased by $120 million due to the borrowing. GARDASIL/GARDASIL 9 sales growth also reflects higher demand in China. Growth was partially offset by the negative impact of the COVID-19 pandemic globally. Excluding the borrowing-related activity in both periods, GARDASIL/GARDASIL 9 sales grew 8% in the quarter, or 6% excluding the favorable impact from foreign exchange.

Growth in hospital acute care reflects higher demand globally for BRIDION (sugammadex) Injection 100 mg/mL, a medicine for the reversal of neuromuscular blockade induced by rocuronium bromide or vecuronium bromide in adults undergoing surgery; and the continued uptake of PREVYMIS (letermovir), a medicine for prophylaxis (prevention) of cytomegalovirus (CMV) infection and disease in adult CMV-seropositive recipients of an allogeneic hematopoietic stem cell transplant.

Pharmaceutical sales in the quarter were negatively affected by the ongoing impacts from the loss of market exclusivity, including for NUVARING (etonogestrel/ethinyl estradiol vaginal ring), ZETIA (ezetimibe) and certain products in diversified brands. In addition, the decline in sales of JANUVIA (sitagliptin) and JANUMET (sitagliptin and metformin HCI) reflects continued pricing pressure in the United States, which more than offset higher demand in certain international markets.

Full-year 2020 pharmaceutical sales increased 3% to $43.0 billion; excluding the unfavorable effect from foreign exchange, sales grew 4%, primarily due to higher sales in oncology, reflecting strong growth in KEYTRUDA, higher sales of certain vaccines including PNEUMOVAX 23 (pneumococcal vaccine polyvalent), a vaccine to help prevent pneumococcal disease, and higher sales of certain hospital acute care products, including PREVYMIS and BRIDION. As discussed above, the COVID-19 pandemic negatively affected sales in 2020. Also negatively affecting sales in 2020 was the ongoing impacts of the loss of market exclusivity for several products, lower sales of pediatric vaccines, as well as pricing pressure in diabetes.

Animal Health Revenue

Animal Health sales totaled $1.2 billion for the fourth quarter of 2020, an increase of 4% compared with the fourth quarter of 2019; excluding the unfavorable effect from foreign exchange, Animal Health sales grew 6%. Growth in the quarter reflects a net favorable impact of one-time items, including an additional month of sales in the current quarter related to the 2019 acquisition of Antelliq Corporation (Antelliq), partially offset by distributor purchasing patterns. Also contributing to growth were contributions from smaller acquisitions, as well as the underlying performance of the business driven by companion animal products, reflecting higher demand in companion animal vaccines and parasiticides.

Worldwide sales for the full year of 2020 were $4.7 billion, an increase of 7%; excluding the unfavorable effect from foreign exchange, sales grew 10%. Full-year sales growth was primarily driven by livestock sales which included an additional five months of sales in the year related to the 2019 acquisition of Antelliq, along with higher sales of companion animal products, primarily the BRAVECTO (fluralaner) line of products for parasitic control, and companion animal vaccines.

Fourth-Quarter and Full-Year Expense, EPS and Related Information

The tables below present selected expense information.

GAAP Expense, EPS and Related Information

Gross margin was 55.8% for the fourth quarter of 2020 compared to 69.1% for the fourth quarter of 2019. The decrease reflects higher acquisition- and divestiture-related costs, including an impairment charge related to ZERBAXA, a charge related to the discontinuation of COVID-19 vaccine development programs, higher inventory write-offs due to a recall of ZERBAXA, pricing pressure and foreign exchange, partially offset by the favorable effects of product mix and manufacturing variances.

Gross margin was 67.7% for the full year of 2020 compared to 69.9% for the full year of 2019. The decrease in gross margin for the full year of 2020 reflects higher acquisition- and divestiture-related costs, including an impairment charge related to ZERBAXA, pricing pressure, a charge related to the discontinuation of COVID-19 vaccine development programs, higher amortization of intangible assets related to collaborations, and higher inventory write-offs, partially offset by the favorable effects of product mix and lower restructuring costs.

Selling, general and administrative expenses were $3.1 billion in the fourth quarter of 2020, an increase of 7% compared to the fourth quarter of 2019. The increase was largely driven by higher acquisition- and divestiture-related costs, primarily reflecting costs related to the company's planned spinoff of Organon & Co. (Organon), as well as a $100 million contribution to the Merck Foundation to support philanthropic programs and initiatives that help address health disparities and strengthen communities in the U.S. and around the world; partially offset by lower selling and administrative costs, including less travel and meeting expenses, due in part to the COVID-19 pandemic. Full-year 2020 selling, general and administrative expenses were $10.5 billion, a decrease of 1% compared to the full year of 2019. The decrease primarily reflects lower administrative, selling and promotional costs, due in part to the COVID-19 pandemic, largely offset by higher acquisition- and divestiture-related costs, primarily reflecting costs related to the company's planned spinoff of Organon.

R&D expenses were $5.8 billion in the fourth quarter of 2020, compared with $2.5 billion in the fourth quarter of 2019. R&D expenses were $13.6 billion for the full year of 2020, a 37% increase compared to the full year of 2019. The increase in both periods was primarily driven by higher upfront payments for acquisitions and collaborations, including a $2.7 billion charge in 2020 for the acquisition of VelosBio. In addition, the increase in both periods reflects higher expenses related to clinical development and increased investment in discovery research and early drug development. These increases were partially offset by lower travel and meeting expenses due to the COVID-19 pandemic, as well as lower acquisition- and divestiture-related costs.

Other (income) expense, net, was $258 million of income in the fourth quarter of 2020 compared to $223 million of income in the fourth quarter of 2019, primarily reflecting higher income from investments in equity securities, net, which was $375 million in 2020 compared with $119 million in 2019, largely from the recognition of unrealized gains on securities. Other (income) expense, net, was $886 million of income for the full year of 2020 compared to $139 million of expense for the full year of 2019, primarily reflecting higher income from investments in equity securities, net, which was $1.3 billion in 2020 compared with $170 million in 2019, largely from the recognition of unrealized gains on securities.

The effective income tax rates were (5.0)% for the fourth quarter and 19.4% for the full year of 2020. The effective income tax rates for the fourth quarter and full year of 2020 reflect the unfavorable impact of the charge for the acquisition of VelosBio for which no tax benefit was recognized.

GAAP EPS was $(0.83) for the fourth quarter of 2020 compared with $0.92 for the fourth quarter of 2019. GAAP EPS was $2.78 for the full year of 2020 compared with $3.81 for the full year of 2019.

Non-GAAP Expense, EPS and Related Information

Non-GAAP gross margin was 73.0% for the fourth quarter of 2020 compared to 72.6% for the fourth quarter of 2019. The increase in the fourth quarter reflects the favorable effects of product mix and manufacturing variances, partially offset by higher inventory write-offs due to a recall of ZERBAXA, pricing pressure and foreign exchange.

Non-GAAP gross margin was 74.3% for the full year of 2020 compared to 74.9% for the full year of 2019. The decrease reflects pricing pressure, higher amortization of intangible assets related to collaborations and higher inventory write-offs, partially offset by the favorable effect of product mix.

Non-GAAP selling, general and administrative expenses were $2.8 billion in the fourth quarter of 2020, a decrease of 2% compared to the fourth quarter of 2019. Full-year 2020 non-GAAP selling, general and administrative expenses were $9.5 billion, a decrease of 9% compared to the full year of 2019. The decrease in both periods primarily reflects lower administrative and selling costs, including less travel and meeting expenses, due in part to the COVID-19 pandemic. The declines were partially offset by the contribution to the Merck Foundation.

Non-GAAP R&D expenses were $2.6 billion in the fourth quarter of 2020, a 12% increase compared to the fourth quarter of 2019. Non-GAAP R&D expenses were $9.2 billion for the full year of 2020, a 6% increase compared to the full year of 2019. The increase in both periods was primarily driven by higher expenses related to clinical development and increased investment in discovery research and early drug development, partially offset by lower travel and meeting expenses due to the COVID-19 pandemic.

Non-GAAP other (income) expense, net, was $253 million of income in the fourth quarter of 2020 compared to $193 million of income in the fourth quarter of 2019, primarily reflecting higher income from investments in equity securities, net, which was $375 million in 2020 compared with $119 million in 2019, largely from the recognition of unrealized gains on securities. Non-GAAP other (income) expense, net, for the full year of 2020 was $916 million of income compared to $200 million of income for the full year of 2019, primarily driven by higher income from investments in equity securities, net, which was $1.3 billion in 2020 compared with $170 million in 2019, largely from the recognition of unrealized gains on securities.

The non-GAAP effective income tax rates were 15.3% for the fourth quarter of 2020 and 15.5% for the full year of 2020.

Non-GAAP EPS was $1.32 for the fourth quarter of 2020 compared with $1.16 for the fourth quarter of 2019. Non-GAAP EPS was $5.94 for the full year of 2020 compared with $5.19 for the full year of 2019.

A reconciliation of GAAP to non-GAAP net income and EPS is provided in the table that follows.

5 Amount for full-year 2020 includes $826 million related to collaborations with Seagen, Inc.

6 Includes the estimated tax impact on the reconciling items. Amount for full-year 2020 includes a tax cost of $67 million, representing an adjustment to the tax benefits recorded in conjunction with the 2015 acquisition of Cubist Pharmaceuticals, Inc. Amount for full-year 2019 includes a $364 million net tax benefit related to the settlement of certain federal income tax matters, an $86 million tax benefit related to the reversal of tax reserves established in conjunction with the divestiture of Merck's Consumer Care business in 2014 as a result of the lapse in the statute of limitations, and a $117 million tax charge related to the finalization of treasury regulations associated with the 2017 enactment of U.S. tax legislation.

Financial Outlook

The guidance provided below is based on the assumption that the Organon business will be part of Merck for all of 2021; however, the Company expects that the Organon spinoff will occur late in the second quarter of 2021. If the spinoff occurs, these financial estimates will be updated.

At mid-January 2021 exchange rates, Merck anticipates full-year 2021 revenue to be between $51.8 billion and $53.8 billion, including a positive impact from foreign exchange of approximately 2%.

Merck expects full-year 2021 GAAP EPS to be between $5.52 and $5.72.

Beginning in 2021, the Company will be changing the treatment of certain items for the purposes of its non-GAAP reporting. Historically, Merck's non-GAAP results excluded the amortization of intangible assets recognized in connection with business acquisitions but did not exclude the amortization of intangibles originating from collaborations, asset acquisitions or licensing arrangements. Beginning in 2021, Merck's non-GAAP results will no longer differentiate between the nature of the intangible assets being amortized and will exclude all amortization of intangible assets. Also, beginning in 2021, Merck's non-GAAP results will exclude gains and losses on investments in equity securities.

On this new basis, Merck expects full-year 2021 non-GAAP EPS to be between $6.48 and $6.68, including an approximately 3% positive impact from foreign exchange. The non-GAAP range also excludes acquisition- and divestiture-related costs and costs related to restructuring programs. The changes to non-GAAP reporting resulted in a positive impact to projected 2021 non-GAAP EPS of approximately $0.08. For comparative purposes, Merck's non-GAAP EPS in 2020 would have been $5.79 if reported under the new basis.

The full-year guidance includes Merck's current assumption of the impact from the COVID-19 pandemic. Merck projects strong underlying business growth for 2021. This growth is partially offset by the anticipated continuing impacts of the pandemic into 2021. Merck believes that global health systems and patients have largely adapted to the impacts of COVID-19 disease, but the company's assumption is that ongoing residual negative impacts will persist, particularly during the first half of 2021 and most notably with respect to vaccine sales, which are expected to be more acute in the United States.

For full-year 2021, Merck assumes an unfavorable impact to revenue of approximately 2% due to the COVID-19 pandemic, all of which relates to pharmaceutical segment sales. For full-year 2021, with respect to the COVID-19 pandemic, Merck expects a net negative impact on operating expenses, as spending on the development of its COVID-19 antiviral programs is expected to exceed the favorable impact of lower spending in other areas due to the COVID-19 pandemic. Neither the sales nor the EPS guidance ranges provided above include the impact of the potential launches of Merck's COVID-19 antiviral drug candidates.

The following table summarizes the company's full-year 2021 financial guidance.

*The company does not have any non-GAAP adjustments to revenue.

**EPS guidance for 2021 assumes a share count (assuming dilution) of approximately 2.53 billion shares.

A reconciliation of anticipated 2021 GAAP EPS to non-GAAP EPS and the items excluded from non-GAAP EPS are provided in the table below.

Merck expects the spinoff of Organon to be completed late in the second quarter of 2021. The transaction is expected to create two companies with enhanced strategic and operational focus, improved agility, simplified operating models, optimized capital structures and improved financial profiles. Merck believes the transaction will deliver significant benefits for both Merck and Organon and create value for Merck shareholders.

In 2020, the products that will comprise Organon achieved revenues of $6.5 billion. In 2021, assuming it operated as an independent company for the full year, Organon is expected to generate $6.0 billion to $6.5 billion in revenue. As it nears the end of loss of exclusivity exposure to key brands, Organon will be well positioned for growth led by its Women's Health and Biosimilars portfolios, with expected low to mid-single digit annual revenue growth off of a 2021 base year.