Filed by Pfizer Inc.

Pursuant to Rule 425 under the Securities Act of 1933, as amended

and deemed filed pursuant to Rule 14a-12

of the Securities Exchange Act of 1934, as amended

Subject Company: Pfizer Inc.

(Commission File No. 001-03619)

The following communications are being filed in connection with the proposed business combination between Mylan N.V. and Upjohn, Pfizer Inc.’s off-patent branded and generic established medicines business

TODAY’S NEWS Colleagues, In addition to second-quarter earnings, this morning we announced that Pfizer and Mylan have agreed to a proposed combination of Upjohn with Mylan. This is an exciting opportunity for Pfizer, Upjohn and patients around the world who rely on our medicines. First and foremost, we are creating a new champion for global health that will deliver more medicines to more patients around the world. The combination of Upjohn’s portfolio of iconic, trusted brands and commercial expertise with Mylan’s innovative pipeline and portfolio, which have a substantial presence in all major therapeutic areas, will position the new combined company to address macro global healthcare needs and better serve patients. This also will allow Pfizer to transition to be a more focused, global leader in science-based innovative medicines. Given the expected continued strength of several key brands launched in recent years, as well as the breadth and depth of our mid- to late-stage pipeline, we believe we will be even better positioned to deliver new medicines for patients, attractive shareholder returns, and engaging opportunities for colleagues. Thank you to Michael Goettler and everyone who has worked so hard in pursuit of this new future for our companies, and for patients. We intend to close by mid-2020, subject to customary closing conditions. In the meantime, we must remain focused on delivering on our purpose: Breakthroughs that change patients’ lives. I look forward to speaking with all of you on Wednesday’s Pfizer Live broadcast where we will discuss our quarterly results, as well as the tremendous opportunities that lie ahead for both Pfizer and Upjohn. Q2 BUSINESS HIGHLIGHTS

Global Revenues $13.3B Operational Revenue Growth 2% Adjusted Diluted EPS Growth 4% Q2 YTD PATIENT IMPACT 2.2M Patients treated for CANCER 2.6K Patients treated for RARE DISEASE 30.9M People immunized with VACCINES 66M Patients treated for PAIN 20.4M Patients treated with ANTI-INFECTIVES 56.6M Patients treated for CVD 2.1M Patients treated for INFLAMMATORY DISEASE 1.7M Patients treated for SMOKING *Patient counts are estimates derived from multiple data sources PIPELINE UPDATE (Since my last update on April 30, 2019) In the U.S., the FDA has approved: ï,· VYNDAQEL® and VYNDAMAX™ for the treatment of ATTR-Cardiomyopathy. ï,· ZIRABEV™, a biosimilar to Avastin®, for the treatment of five different types of cancer. ï,· A new indication for INFLECTRA®, a biosimilar for Remicade®, which is now approved for pediatric patients 6 years of age and older with moderately to severely active ulcerative colitis. ï,· RUXIENCE™, a biosimilar for Rituzan®, for the treatment of certain cancers and autoimmune conditions. ï,· BAVENCIO® in combination with INLYTA® for the first-line treatment of patients with advanced renal cell carcinoma.

In Europe, the EC has approved: " TALZENNA(R) for patients with inherited (germline) BRCA-mutated, locally advanced or metastatic breast cancer. " LORVIQUA(R) for treatment of adult patients with ALK-positive advanced non-small cell lung cancer. Pipeline Snapshot (As of July 29, 2019)

ADDITIONAL INFORMATION

This communication shall not constitute an offer to sell or the solicitation of an offer to sell or the solicitation of an offer to buy any securities, nor shall there be any sale of securities in any jurisdiction in which such offer, solicitation or sale would be unlawful prior to registration or qualification under the securities laws of any such jurisdiction. No offer of securities shall be made except by means of a prospectus meeting the requirements of Section 10 of the Securities Act of 1933, as amended (the “Securities Act”). In connection with the proposed combination of Upjohn Inc. (“Upjohn”), a wholly owned subsidiary of Pfizer Inc. (“Pfizer”) and Mylan N.V. (“Mylan”), which will immediately follow the proposed separation of Upjohn from Pfizer (the “proposed transaction”), Upjohn, Mylan and Mylan I B.V., a wholly owned subsidiary of Mylan, (“Mylan Newco”) intend to file relevant materials with the Securities and Exchange Commission (“SEC”), including a registration statement on Form S-4 that will include a proxy statement/prospectus relating to the proposed transaction. In addition, Upjohn expects to file a registration statement in connection with its separation from Pfizer. INVESTORS AND SECURITY HOLDERS ARE URGED TO READ THE REGISTRATION STATEMENTS, PROXY STATEMENT/PROSPECTUS AND ANY OTHER RELEVANT DOCUMENTS WHEN THEY BECOME AVAILABLE BECAUSE THEY WILL CONTAIN IMPORTANT INFORMATION ABOUT MYLAN, UPJOHN, MYLAN NEWCO AND THE PROPOSED TRANSACTION. A definitive proxy statement will be sent to shareholders of Mylan seeking approval of the proposed transaction. The documents relating to the proposed transaction (when they are available) can be obtained free of charge from the SEC’s website at www.sec.gov. These documents (when they are available) can also be obtained free of charge from Mylan, upon written request to Mylan, at (724) 514-1813 or investor.relations@mylan.com or from Pfizer on Pfizer’s internet website at https://investors.Pfizer.com/financials/sec-filings/default.aspx or by contacting Pfizer’s Investor Relations Department at (212) 733-2323.

FORWARD LOOKING STATEMENTS

This communication contains “forward-looking statements”. These statements are made pursuant to the safe harbor provisions of the Private Securities Litigation Reform Act of 1995. Such forward-looking statements may include, without limitation, statements about the proposed transaction, the expected timetable for completing the proposed transaction, the benefits and synergies of the proposed transaction, future opportunities for the combined company and products and any other statements regarding Pfizer’s, Mylan’s and Upjohn’s future operations, financial or operating results, capital allocation, dividend policy, debt ratio, anticipated business levels, future earnings, planned activities, anticipated growth, market opportunities, strategies, competitions, and other expectations and targets for future periods. Forward-looking statements may often be identified by the use of words such as “will”, “may”, “could”, “should”, “would”, “project”, “believe”, “anticipate”, “expect”, “plan”, “estimate”, “forecast”, “potential”, “intend”, “continue”, “target” and variations of these words or comparable words. Because forward-looking statements inherently involve risks and uncertainties, actual future results may differ materially from those expressed or implied by such forward-looking statements. Factors that could cause or contribute to such differences include, but are not limited to: the parties’ ability to meet expectations regarding the timing, completion and accounting and tax treatments of the proposed transaction; changes in relevant tax and other

laws; the parties’ ability to consummate the proposed transaction; the conditions to the completion of the proposed transaction, including receipt of approval of Mylan’s shareholders, not being satisfied or waived on the anticipated timeframe or at all; the regulatory approvals required for the proposed transaction not being obtained on the terms expected or on the anticipated schedule or at all; inherent uncertainties involved in the estimates and judgments used in the preparation of financial statements and the providing of estimates of financial measures, in accordance with the accounting principles generally accepted in the United States of America (“U.S. GAAP”) and related standards, or on an adjusted basis (“Non-GAAP measures”); the integration of Mylan and Upjohn being more difficult, time consuming or costly than expected; Mylan’s and Upjohn’s failure to achieve expected or targeted future financial and operating performance and results; the possibility that the combined company may be unable to achieve expected benefits, synergies and operating efficiencies in connection with the proposed transaction within the expected time frames or at all or to successfully integrate Mylan and Upjohn; customer loss and business disruption being greater than expected following the proposed transaction; the retention of key employees being more difficult following the proposed transaction; Mylan and Upjohn’s capacity to bring new products to market, including but not limited to where it uses its business judgment and decides to manufacture, market and/or sell products directly or through third parties, notwithstanding the fact that allegations of patent infringement(s) have not been finally resolved by the courts (i.e., an “at-risk launch”); the scope, timing and outcome of any ongoing legal proceedings and the impact of such proceedings on Mylan’s and Upjohn’s consolidated financial condition, results of operations and/or cash flows; Mylan’s and Upjohn’s ability to protect their respective intellectual property and preserve their respective intellectual property rights; the effect of any changes in customer and supplier relationships and customer purchasing patterns; the ability to attract and retain key personnel; changes in third-party relationships; the impacts of competition; changes in the economic and financial conditions of the business of Mylan or Upjohn; and uncertainties and matters beyond the control of management and other factors described under “Risk Factors” in each of Pfizer’s and Mylan’s Annual Reports on Form 10-K, Quarterly Reports on Form 10-Q and other filings with the SEC. You can access Pfizer’s or Mylan’s filings with the SEC through the SEC website at www.sec.gov or through Pfizer’s or Mylan’s website, and Pfizer and Mylan strongly encourage you to do so. Except as required by applicable law, Pfizer, Mylan or Upjohn undertake no obligation to update any statements herein for revisions or changes after the date of this communication.

PARTICIPANTS IN THE SOLICITATION

This communication is not a solicitation of a proxy from any investor or security holder. However, Pfizer, Mylan, Upjohn and certain of their respective directors and executive officers may be deemed to be participants in the solicitation of proxies in connection with the proposed transaction under the rules of the SEC. Information about the directors and executive officers of Pfizer may be found in its Annual Report on Form 10-K filed with the SEC on February 28, 2019, its definitive proxy statement and additional proxy statement relating to its 2019 Annual Meeting filed with the SEC on March 14, 2019 and on April 2, 2019, respectively, and Current Report on Form 8-K filed with the SEC on June 27, 2019. Information about the directors and executive officers of Mylan may be found in its amended Annual Report on Form 10-K filed with the SEC on April 30, 2019, and its definitive proxy statement relating to its 2019 Annual Meeting filed with the SEC on May 24, 2019. These documents can be obtained free of charge from the sources indicated above. Additional information regarding the interests of these participants will also be included in the proxy statement/prospectus when it becomes available.