Summary of Significant Accounting Policies (Policies)	9 Months Ended
Sep. 28, 2025
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation The accompanying Condensed Consolidated Financial Statements include Belden Inc. and all of its subsidiaries (the Company, us, we, or our). We eliminate all significant affiliate accounts and transactions in consolidation. The accompanying Condensed Consolidated Financial Statements presented as of any date other than December 31, 2024: •Are prepared from the books and records without audit, and •Are prepared in accordance with the instructions for Form 10-Q and do not include all of the information required by accounting principles generally accepted in the United States for complete statements, but •Include all adjustments, consisting only of normal recurring adjustments, necessary for a fair presentation of the financial statements. These Condensed Consolidated Financial Statements should be read in conjunction with the Consolidated Financial Statements and Supplementary Data contained in our 2024 Annual Report on Form 10-K.
Business Description	Business Description Belden Inc. (the Company, us, we, or our) is a leading global supplier of complete connection solutions built around two global businesses - Smart Infrastructure Solutions and Automation Solutions. We sell our products to distributors, end-users, installers, and directly to original equipment manufacturers (OEMs). We have manufacturing and other operating facilities in the U.S., Canada, China, India, Mexico, Tunisia, and various countries in Europe.
Reporting Periods	Reporting Periods Our fiscal year and fiscal fourth quarter both end on December 31. Our fiscal first quarter ends on the Sunday falling closest to 91 days after December 31, which was March 30, 2025, the 89th day of our fiscal year 2025. Our fiscal second and third quarters each have 91 days. The nine months ended September 28, 2025 and September 29, 2024 included 271 and 273 days, respectively.
Fair Value Measurement	Fair Value Measurement Accounting guidance for fair value measurements specifies a hierarchy of valuation techniques based upon whether the inputs to those valuation techniques reflect assumptions other market participants would use based upon market data obtained from independent sources or reflect our own assumptions of market participant valuation. The hierarchy is broken down into three levels based on the reliability of the inputs as follows: •Level 1 – Quoted prices in active markets that are unadjusted and accessible at the measurement date for identical, unrestricted assets or liabilities; •Level 2 – Quoted prices for identical assets and liabilities in markets that are not active, quoted prices for similar assets and liabilities in active markets, or financial instruments for which significant inputs are observable, either directly or indirectly; and •Level 3 – Prices or valuations that require inputs that are both significant to the fair value measurement and unobservable.
Cash and Cash Equivalents	Cash and Cash Equivalents We classify cash on hand and deposits in banks, including commercial paper, money market accounts, and other investments with an original maturity of three months or less, that we hold from time to time, as cash and cash equivalents. We periodically have cash equivalents consisting of short-term money market funds and other investments. As of September 28, 2025, we did not have any such cash equivalents on hand. The primary objective of our investment activities is to preserve our capital for the purpose of funding operations. We do not enter into investments for trading or speculative purposes.
Contingent Liabilities	Contingent Liabilities We have established liabilities for environmental and legal contingencies that are probable of occurrence and reasonably estimable, the amounts of which are currently not material. We accrue environmental remediation costs based on estimates of known environmental remediation exposures developed in consultation with our environmental consultants and legal counsel. We are, from time to time, subject to routine litigation incidental to our business. Historically, these lawsuits have primarily involved claims for damages arising out of the use of our products, allegations of patent or trademark infringement, and litigation and administrative proceedings involving employment matters and commercial disputes. Based on facts currently available, we believe the disposition of the claims that are pending or asserted will not have a material adverse effect on our financial position, results of operations, or cash flow.
Revenue Recognition	Revenue Recognition We recognize revenue consistent with the principles as outlined in the following five step model: (1) identify the contract with the customer, (2) identify the performance obligations in the contract, (3) determine the transaction price, (4) allocate the transaction price to the performance obligations in the contract, and (5) recognize revenue when (or as) each performance obligation is satisfied. See Note 2.
Subsequent Events	Subsequent Events We evaluated subsequent events after the balance sheet date through the financial statement issuance date for appropriate accounting and disclosure.
Current Year Adoption of Accounting Pronouncements and Pending Adoption of Recent Accounting Pronouncements	Current Year Adoption of Accounting Pronouncements None of the accounting pronouncements that became effective during 2025 had a material impact to our condensed consolidated financial statements or disclosures. Pending Adoption of Recent Accounting Pronouncements In December 2023, the FASB issued ASU 2023-09, Income Taxes (Topic 740) Improvements to Income Tax Disclosures (ASU 2023-09) enhancing the transparency and decision usefulness of income tax disclosures. ASU 2023-09 addresses investor requests for more transparency about income tax information through improvements to income tax disclosures primarily related to the rate reconciliation and income taxes paid information. ASU 2023-09 is effective for annual periods beginning after December 15, 2024, with early adoption permitted. The amendments in ASU 2023-09 are applied on a prospective basis, though retrospective application is permitted. We did not early adopt this pronouncement and are in the process of evaluating its impact on our consolidated financial statements and related disclosures. In November 2024, the FASB issued guidance to improve the disclosure of expenses in commonly presented expense captions. The new guidance requires a public entity to provide tabular disclosure, on an annual and interim basis, of amounts for the following expense categories: (1) purchases of inventory, (2) employee compensation, (3) depreciation and (4) intangible asset amortization, as included in each relevant expense caption. A relevant expense caption is an expense caption presented on the face of the income statement that contains any of the expense categories noted. Additionally, on an annual and interim basis, a qualitative description is required for amounts remaining in relevant expense captions that are not separately disaggregated quantitatively. The guidance also requires certain amounts that are currently required to be disclosed to be included in the same tabular disclosure as these disaggregation requirements. Furthermore, on an annual and interim basis, a public entity is required to separately disclose selling expenses and annually, disclose a description of the selling expenses. The guidance is effective for 2027 annual reporting, and in the first quarter of 2028 for interim reporting, with early adoption permitted, to be applied on a prospective basis, with retrospective application permitted. We will adopt the guidance when it becomes effective, in our 2027 annual reporting and each quarter thereafter, on a prospective basis.

Summary of Significant Accounting Policies (Policies)

9 Months Ended

Sep. 28, 2025

The accompanying Condensed Consolidated Financial Statements include Belden Inc. and all of its subsidiaries (the Company, us, we, or our). We eliminate all significant affiliate accounts and transactions in consolidation. The accompanying Condensed Consolidated Financial Statements presented as of any date other than December 31, 2024:

•Are prepared from the books and records without audit, and

•Are prepared in accordance with the instructions for Form 10-Q and do not include all of the information required by accounting principles generally accepted in the United States for complete statements, but

•Include all adjustments, consisting only of normal recurring adjustments, necessary for a fair presentation of the financial statements.

These Condensed Consolidated Financial Statements should be read in conjunction with the Consolidated Financial Statements and Supplementary Data contained in our 2024 Annual Report on Form 10-K.

Business Description

Belden Inc. (the Company, us, we, or our) is a leading global supplier of complete connection solutions built around two global

businesses - Smart Infrastructure Solutions and Automation Solutions. We sell our products to distributors, end-users, installers,

and directly to original equipment manufacturers (OEMs). We have manufacturing and other operating facilities in the U.S., Canada, China, India, Mexico, Tunisia, and various countries in Europe.

Reporting Periods

Our fiscal year and fiscal fourth quarter both end on December 31. Our fiscal first quarter ends on the Sunday falling closest to 91 days after December 31, which was March 30, 2025, the 89th day of our fiscal year 2025. Our fiscal second and third quarters each have 91 days. The nine months ended September 28, 2025 and September 29, 2024 included 271 and 273 days, respectively.

Fair Value Measurement

Accounting guidance for fair value measurements specifies a hierarchy of valuation techniques based upon whether the inputs to those valuation techniques reflect assumptions other market participants would use based upon market data obtained from independent sources or reflect our own assumptions of market participant valuation. The hierarchy is broken down into three levels based on the reliability of the inputs as follows:

•Level 1 – Quoted prices in active markets that are unadjusted and accessible at the measurement date for identical, unrestricted assets or liabilities;

•Level 2 – Quoted prices for identical assets and liabilities in markets that are not active, quoted prices for similar assets and liabilities in active markets, or financial instruments for which significant inputs are observable, either directly or indirectly; and

•Level 3 – Prices or valuations that require inputs that are both significant to the fair value measurement and unobservable.

Cash and Cash Equivalents

We classify cash on hand and deposits in banks, including commercial paper, money market accounts, and other investments with an original maturity of three months or less, that we hold from time to time, as cash and cash equivalents. We periodically have cash equivalents consisting of short-term money market funds and other investments. As of September 28, 2025, we did not have any such cash equivalents on hand. The primary objective of our investment activities is to preserve our capital for the purpose of funding operations. We do not enter into investments for trading or speculative purposes.

Contingent Liabilities

We have established liabilities for environmental and legal contingencies that are probable of occurrence and reasonably estimable, the amounts of which are currently not material. We accrue environmental remediation costs based on estimates of known environmental remediation exposures developed in consultation with our environmental consultants and legal counsel. We are, from time to time, subject to routine litigation incidental to our business. Historically, these lawsuits have primarily involved claims for damages arising out of the use of our products, allegations of patent or trademark infringement, and litigation and administrative proceedings involving employment matters and commercial disputes. Based on facts currently available, we believe the disposition of the claims that are pending or asserted will not have a material adverse effect on our financial position, results of operations, or cash flow.

Revenue Recognition

We recognize revenue consistent with the principles as outlined in the following five step model: (1) identify the contract with the customer, (2) identify the performance obligations in the contract, (3) determine the transaction price, (4) allocate the transaction price to the performance obligations in the contract, and (5) recognize revenue when (or as) each performance obligation is satisfied. See Note 2.

Subsequent Events

We evaluated subsequent events after the balance sheet date through the financial statement issuance date for appropriate accounting and disclosure.

Current Year Adoption of Accounting Pronouncements and Pending Adoption of Recent Accounting Pronouncements

Current Year Adoption of Accounting Pronouncements

None of the accounting pronouncements that became effective during 2025 had a material impact to our condensed consolidated financial statements or disclosures.

Pending Adoption of Recent Accounting Pronouncements

In December 2023, the FASB issued ASU 2023-09, Income Taxes (Topic 740) Improvements to Income Tax Disclosures (ASU 2023-09) enhancing the transparency and decision usefulness of income tax disclosures. ASU 2023-09 addresses investor requests for more transparency about income tax information through improvements to income tax disclosures primarily related to the rate reconciliation and income taxes paid information. ASU 2023-09 is effective for annual periods beginning after December 15, 2024, with early adoption permitted. The amendments in ASU 2023-09 are applied on a prospective basis, though retrospective application is permitted. We did not early adopt this pronouncement and are in the process of evaluating its impact on our consolidated financial statements and related disclosures.

In November 2024, the FASB issued guidance to improve the disclosure of expenses in commonly presented expense captions. The new guidance requires a public entity to provide tabular disclosure, on an annual and interim basis, of amounts for the following expense categories: (1) purchases of inventory, (2) employee compensation, (3) depreciation and (4) intangible asset amortization, as included in each relevant expense caption. A relevant expense caption is an expense caption presented on the face of the income statement that contains any of the expense categories noted. Additionally, on an annual and interim basis, a qualitative description is required for amounts remaining in relevant expense captions that are not separately disaggregated quantitatively. The guidance also requires certain amounts that are currently required to be disclosed to be included in the same tabular disclosure as these disaggregation requirements. Furthermore, on an annual and interim basis, a public entity is required to separately disclose selling expenses and annually, disclose a description of the selling expenses. The guidance is effective for 2027 annual reporting, and in the first quarter of 2028 for interim reporting, with early adoption permitted, to be applied on a prospective basis, with retrospective application permitted. We will adopt the guidance when it becomes effective, in our 2027 annual reporting and each quarter thereafter, on a prospective basis.