LFUS

SEC.gov | Request Rate Threshold Exceeded

U.S. Securities and Exchange Commission

You’ve Exceeded the SEC’s Traffic Limit

Your request rate has exceeded the SEC’s maximum allowable requests per second. Your access to SEC.gov will be limited for 10 minutes.

Current guidelines limit each user to a total of no more than 10 requests per second, regardless of the number of machines used to submit requests. To ensure that SEC.gov remains available to all users, we reserve the right to block IP addresses that submit excessive requests.

The block will be lifted automatically by waiting 10 minutes. Continuing to exceed the SEC’s maximum allowable request rate during the time-out period will extend the duration of the time-out period. To ensure fair access for all users, please reduce the rate of your requests and visit SEC.gov again after the 10 minute time-out period has passed.

For best practices on efficiently downloading information from SEC.gov, including the latest EDGAR filings, visit sec.gov/developer. You can also sign up for email updates on the SEC open data program, including best practices that make it more efficient to download data, and SEC.gov enhancements that may impact scripted downloading processes. For more information, contact opendata@sec.gov.

For more information, please see the SEC’s Web Site Privacy and Security Policy. Thank you for your interest in the U.S. Securities and Exchange Commission.

Reference ID: 0.c706d217.1784472432.ece1bd36

More Information

Internet Security Policy

By using this site, you are agreeing to security monitoring and auditing. For security purposes, and to ensure that the public service remains available to users, this government computer system employs programs to monitor network traffic to identify unauthorized attempts to upload or change information or to otherwise cause damage, including attempts to deny service to users.

Unauthorized attempts to upload information and/or change information on any portion of this site are strictly prohibited and are subject to prosecution under the Computer Fraud and Abuse Act of 1986 and the National Information Infrastructure Protection Act of 1996 (see Title 18 U.S.C. §§ 1001 and 1030).

To ensure our website performs well for all users, the SEC monitors the frequency of requests for SEC.gov content to ensure automated searches do not impact the ability of others to access SEC.gov content. We reserve the right to block IP addresses that submit excessive requests. Current guidelines limit users to a total of no more than 10 requests per second, regardless of the number of machines used to submit requests.

If a user or application submits more than 10 requests per second, further requests from the IP address(es) may be limited for a brief period. Once the rate of requests has dropped below the threshold for 10 minutes, the user may resume accessing content on SEC.gov. This SEC practice is designed to limit excessive automated searches on SEC.gov and is not intended or expected to impact individuals browsing the SEC.gov website.

Note that this policy may change as the SEC manages SEC.gov to ensure that the website performs efficiently and remains available to all users.

Note: We do not offer technical support for developing or debugging scripted downloading processes.

lfus-202601280000889331falseLITTELFUSE INC /DE00008893312026-01-282026-01-28

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

WASHINGTON, D.C. 20579

FORM 8-K

CURRENT REPORT

PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934

Date of Report: January 28, 2026 (Date of earliest event reported)

LITTELFUSE, INC.

(Exact name of registrant as specified in its charter) Delaware0-2038836-3795742 (State of other jurisdiction of incorporation)(Commission File Number)(IRS Employer Identification No.)

6133 North River Road, Suite 500, Rosemont, IL 60018 (Address of principal executive offices) (Zip Code)

Registrant’s telephone number, including area code: (773) 628-1000

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:

☐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 ClassTrading SymbolName of exchange on which registered Common Stock, par value $0.01 per shareLFUSNASDAQ Global Select Market

Indicate by check mark whether the registrant is an emerging growth company as defined in Rule 405 of the Securities Act of 1933 (17 CFR §230.405) or Rule 12b-2 of the Securities Exchange Act of 1934 (17 CFR §240.12b-2). 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 2.02Results of Operations and Financial Condition

The information contained within Item 2.02 of this Form 8-K and the Exhibits attached hereto shall not be deemed to be "filed" for purposes of Section 18 of the Securities Exchange Act of 1934, as amended, and shall not be deemed incorporated by reference into any filing under the Securities Act of 1933, as amended, except as shall be expressly set forth by specific reference in such filing.

On January 28, 2026, Littelfuse, Inc. (the “Company”) issued a press release announcing the results of its operations for the quarter and full year ended December 27, 2025. A copy of the press release is attached as Exhibit 99.1 to this Form 8-K and incorporated by reference to this Item 2.02 as if fully set forth herein. A copy of the press release will also be available on the Company’s website.

Item 7.01Regulation FD Disclosure

To supplement the information in the attached press release, the Company has also prepared a presentation, which will be available on the Company’s website at https://investor.littelfuse.com/events-and-presentations and is attached hereto as Exhibit 99.2 to this Current Report on Form 8-K.

The information contained in the press release and investor presentation attached to this Form 8-K includes forward-looking statements that are intended to be covered by the safe-harbor provisions of the Private Securities Litigation Reform Act of 1995. These forward-looking statements include but are not limited to comments with respect to the objectives and strategies, financial condition, results of operations and business of the Company. These forward-looking statements involve numerous assumptions, inherent risks and uncertainties, both general and specific, and the risk that predictions and other forward-looking statements will not be achieved. The Company cautions you not to place undue reliance on these forward-looking statements as a number of important factors could cause actual future results to differ materially from the plans, objectives, expectations, estimates and intentions expressed in such forward-looking statements.

A copy of the press release is also posted on the Company’s website.

Item 9.01Financial Statements and Exhibits.

(d)Exhibits The following exhibits are furnished with this Form 8-K: 99.1 Press Release dated January 28, 2026

99.2 Littelfuse Presentation dated January 28, 2026

104 Cover Page Interactive Data File (embedded within the Inline XBRL document)

Signature

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 thereunto duly authorized.

Littelfuse, Inc.

Date: January 28, 2026By: /s/ Abhishek Khandelwal Abhishek Khandelwal Executive Vice President and Chief Financial Officer

lfus-202510290000889331falseLITTELFUSE INC /DE00008893312025-10-292025-10-29

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

WASHINGTON, D.C. 20579

FORM 8-K

CURRENT REPORT

PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934

Date of Report: October 29, 2025 (Date of earliest event reported)

LITTELFUSE, INC.

(Exact name of registrant as specified in its charter)

Delaware0-2038836-3795742 (State of other jurisdiction of incorporation)(Commission File Number)(IRS Employer Identification No.)

6133 North River Road, Suite 500, Rosemont, IL 60018 (Address of principal executive offices) (Zip Code)

Registrant’s telephone number, including area code: (773) 628-1000

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:

☐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 ClassTrading SymbolName of exchange on which registered Common Stock, par value $0.01 per shareLFUSNASDAQ Global Select Market

Indicate by check mark whether the registrant is an emerging growth company as defined in Rule 405 of the Securities Act of 1933 (17 CFR §230.405) or Rule 12b-2 of the Securities Exchange Act of 1934 (17 CFR §240.12b-2). 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 2.02Results of Operations and Financial Condition

The information contained within Item 2.02 of this Form 8-K and the Exhibits attached hereto shall not be deemed to be "filed" for purposes of Section 18 of the Securities Exchange Act of 1934, as amended, and shall not be deemed incorporated by reference into any filing under the Securities Act of 1933, as amended, except as shall be expressly set forth by specific reference in such filing.

On October 29, 2025, Littelfuse, Inc. (the “Company”) issued a press release announcing the results of its operations for the quarter ended September 27, 2025. A copy of the press release is attached as Exhibit 99.1 to this Form 8-K and incorporated by reference to this Item 2.02 as if fully set forth herein. A copy of the press release will also be available on the Company’s website.

Item 7.01Regulation FD Disclosure

To supplement the information in the attached press release, the Company has also prepared a presentation, which will be available on the Company’s website at https://investor.littelfuse.com/events-and-presentations and is attached hereto as Exhibit 99.2 to this Current Report on Form 8-K.

The information contained in the press release and investor presentation attached to this Form 8-K includes forward-looking statements that are intended to be covered by the safe-harbor provisions of the Private Securities Litigation Reform Act of 1995. These forward-looking statements include but are not limited to comments with respect to the objectives and strategies, financial condition, results of operations and business of the Company. These forward-looking statements involve numerous assumptions, inherent risks and uncertainties, both general and specific, and the risk that predictions and other forward-looking statements will not be achieved. The Company cautions you not to place undue reliance on these forward-looking statements as a number of important factors could cause actual future results to differ materially from the plans, objectives, expectations, estimates and intentions expressed in such forward-looking statements.

A copy of the press release is also posted on the Company's website.

Item 9.01Financial Statements and Exhibits.

(d)Exhibits The following exhibits are furnished with this Form 8-K: 99.1 Press Release dated October 29, 2025

99.2 Littelfuse Presentation dated October 29, 2025

104 Cover Page Interactive Data File (embedded within the Inline XBRL document)

Signature

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 thereunto duly authorized.

Littelfuse, Inc.

Date: October 29, 2025 By: /s/ Abhishek Khandelwal Abhishek Khandelwal Executive Vice President and Chief Financial Officer