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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.c706d217.1784585210.cde4c94

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.

VERTEX, INC._February 11, 2026 0001806837false00018068372026-02-112026-02-11 ​ ​

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): February 11, 2026

VERTEX, INC.

(Exact name of registrant as specified in its charter)

Delaware ​ ​ ​ 001-39413 ​ ​ ​ 23-2081753

(State or other jurisdiction of incorporation or organization)

(Commission File Number)

(I.R.S. Employer Identification No.)

​ 2301 Renaissance Blvd. King of Prussia, Pennsylvania 19406 (Address of principal executive offices) (Zip Code) (800) 355-3500 (Registrant’s telephone number, include area code) N/A (Former Name or Former Address, if Changed Since Last Report)

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 class ​ ​ Trading Symbol(s) ​ ​ ​ Name of each exchange on which registered

Class A Common Stock, $0.001 par value per share ​

VERX

​ The Nasdaq Stock Market LLC

​ 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 February 11, 2026, Vertex, Inc. (the “Company”) issued a press release announcing its financial results for the fourth quarter and full year ended December 31, 2025. A copy of the press release is furnished as Exhibit 99.1 to this Current Report on Form 8-K. The information contained in this Item 2.02, including Exhibit 99.1 hereto, shall not be deemed “filed” for purposes of Section 18 of the Securities Exchange Act of 1934, as amended (the “Exchange Act”), or otherwise subject to the liabilities of that section, nor shall it be deemed incorporated by reference in any filing made by the Company under the Securities Act of 1933, as amended, or the Exchange Act, regardless of any general incorporation language in such filings, unless expressly incorporated by specific reference in such filing. Item 9.01. Financial Statements and Exhibits. (d) Exhibits. The following exhibit relating to Item 2.02 shall be deemed to be furnished, and not filed: ​ Exhibit No. ​ ​ ​ Description

99.1

Press Release dated February 11, 2026

104 ​ Cover Page Interactive Data File (formatted as inline XBRL and contained in Exhibit 101)

​ ​ ​

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. ​

VERTEX, INC.

Date: February 11, 2026 By: /s/ Bryan Rowland

Name: Bryan Rowland

Title: General Counsel and Secretary

​ ​ ​ ​ ​ ​