Results of Operations

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of Report (Date of earliest event reported): April 23, 2026 THERMO FISHER SCIENTIFIC INC. (Exact name of Registrant as specified in its Charter) Delaware 1-8002 04-2209186 (State of incorporation) (Commission File Number) (I.R.S. Employer Identification Number) 168 Third Avenue Waltham , Massachusetts 02451 (Address of principal executive offices) (Zip Code) Registrant’s telephone number, including area code: ( 781 ) 622-1000 Check the appropriate box below if the Form 8-K filing is intended to simultaneously satisfy the filing obligation of the registrant under any of the following provisions ( see General Instruction A.2. below): ☐       Written communications pursuant to Rule 425 under the Securities Act (17 CFR 230.425) ☐        Soliciting material pursuant to Rule 14a-12 under the Exchange Act (17 CFR 240.14a-12) ☐       Pre-commencement communications pursuant to Rule 14d-2(b) under the Exchange Act (17 CFR 240.14d-2(b)) ☐       Pre-commencement communications pursuant to Rule 13e-4(c) under the Exchange Act (17 CFR 240.13e-4(c)) Securities registered pursuant to Section 12(b) of the Act: Title of each class Trading Symbol(s) Name of each exchange on which registered Common Stock, $1.00 par value TMO New York Stock Exchange 1.450% Notes due 2027 TMO 27 New York Stock Exchange 1.750% Notes due 2027 TMO 27B New York Stock Exchange Floating Rate Notes due 2027 TMO 27D New York Stock Exchange 0.500% Notes due 2028 TMO 28A New York Stock Exchange 1.375% Notes due 2028 TMO 28 New York Stock Exchange 1.950% Notes due 2029 TMO 29 New York Stock Exchange 0.875% Notes due 2031 TMO 31 New York Stock Exchange 2.375% Notes due 2032 TMO 32 New York Stock Exchange 3.650% Notes due 2034 TMO 34 New York Stock Exchange 3.628% Notes due 2035 TMO 35A New York Stock Exchange 2.875% Notes due 2037 TMO 37 New York Stock Exchange 1.500% Notes due 2039 TMO 39 New York Stock Exchange 1.875% Notes due 2049 TMO 49 New York Stock Exchange Indicate by check mark whether the registrant is an emerging growth company as defined in Rule 405 of the Securities Act of 1933 (§230.405 of this chapter) or Rule 12b-2 of the Securities Exchange Act of 1934 (§240.12b-2 of this chapter).        Emerging growth company ☐    If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act.   ☐ Item 2.02    Results of Operations and Financial Condition. On April 23, 2026, the Registrant announced its financial results for the fiscal quarter ended March 28, 2026. The full text of the press release issued in connection with the announcement is furnished as Exhibit 99.1 to this Form 8-K and incorporated herein by reference. The information contained in this report and exhibits hereto shall not be deemed "filed" for purposes of Section 18 of the Securities Exchange Act of 1934 (the "Exchange Act") or otherwise subject to the liabilities of that section, nor shall it be deemed incorporated by reference in any filing under the Securities Act of 1933 or the Exchange Act, except as expressly set forth by specific reference in such filing. Item 9.01    Financial Statements and Exhibits. (d)    Exhibits 99.1 Press Release dated April 23, 2026 104 Cover Page Interactive Data File (embedded within the Inline XBRL document) 2 SIGNATURES Pursuant to the requirements of the Securities Exchange Act of 1934, the Registrant has duly caused this report to be signed on its behalf by the undersigned hereunto duly authorized. THERMO FISHER SCIENTIFIC INC. Date: April 23, 2026 By: /s/ Joseph R. Holmes Joseph R. Holmes Vice President and Chief Accounting Officer 3