Subsequent Events	6 Months Ended
Jun. 30, 2026
Subsequent Events [Abstract]
Subsequent Events	18. SUBSEQUENT EVENTS New Credit Agreement On July 21, 2026, ADTRAN Holdings, Inc. as guarantor, ADTRAN, Inc., a Delaware corporation, and Adtran Networks SE, a European stock corporation (the “German Borrower” and together with the US Borrower, collectively, the “Borrowers”), entered into a credit agreement with J.P. Morgan Chase Bank, N.A., as administrative agent for the US Borrower and J.P. Morgan SE, as administrative agent for the German Borrower, and the financial institutions party thereto, as lenders. The New Credit Agreement allows for borrowings of up to $350.0 million in aggregate principal amount, with borrowings by the German Borrower limited to $50.0 million. The New Credit Agreement matures in July 2031 and provides for borrowings bearing interest, at the Company’s election, at either the Term Benchmark Rate or the Base Rate, in each case subject to a 0.00% floor, plus an applicable margin based on the consolidated total net leverage ratio. The applicable margin ranges from 2.25% to 3.25% for Term Benchmark Rate loans and from 1.25% to 2.25% for Base Rate loans. The Borrowers are also required to pay a commitment fee of 0.25% on unused revolving commitments. The New Credit Agreement replaces the Borrowers’ Former Credit Agreement with Wells Fargo Bank, National Association, as administrative agent, entered into on July 18, 2022. The proceeds of any loans are expected to be used for general corporate purposes not prohibited under the New Credit Agreement. Under the New Credit Agreement, the Company agreed to maintain certain leverage ratios and certain fixed charge coverage ratios commencing with the fiscal quarter ending December 31, 2026. In connection with entering into the New Credit Agreement, on July 21, 2026, the Company terminated the Former Credit Agreement with Wells Fargo, the collateral agreement dated July 18, 2022, the ADVA domestic collateral agreement dated June 4, 2024, the guaranty agreement dated July 18, 2022 and the ADVA guaranty agreement dated June 4, 2024 and all principal amounts under the Former Credit Agreement were repaid.

Subsequent Events

6 Months Ended

Jun. 30, 2026

18. SUBSEQUENT EVENTS

New Credit Agreement

On July 21, 2026, ADTRAN Holdings, Inc. as guarantor, ADTRAN, Inc., a Delaware corporation, and Adtran Networks SE, a European stock corporation (the “German Borrower” and together with the US Borrower, collectively, the “Borrowers”), entered into a credit agreement with J.P. Morgan Chase Bank, N.A., as administrative agent for the US Borrower and J.P. Morgan SE, as administrative agent for the German Borrower, and the financial institutions party thereto, as lenders. The New Credit Agreement allows for borrowings of up to $350.0 million in aggregate principal amount, with borrowings by the German Borrower limited to $50.0 million. The New Credit Agreement matures in July 2031 and provides for borrowings bearing interest, at the Company’s election, at either the Term Benchmark Rate or the Base Rate, in each case subject to a 0.00% floor, plus an applicable margin based on the consolidated total net leverage ratio. The applicable margin ranges from 2.25% to 3.25% for Term Benchmark Rate loans and from 1.25% to 2.25% for Base Rate loans. The Borrowers are also required to pay a commitment fee of 0.25% on unused revolving commitments. The New Credit Agreement replaces the Borrowers’ Former Credit Agreement with Wells Fargo Bank, National Association, as administrative agent, entered into on July 18, 2022. The proceeds of any loans are expected to be used for general corporate purposes not prohibited under the New Credit Agreement. Under the New Credit Agreement, the Company agreed to maintain certain leverage ratios and certain fixed charge coverage ratios commencing with the fiscal quarter ending December 31, 2026.

In connection with entering into the New Credit Agreement, on July 21, 2026, the Company terminated the Former Credit Agreement with Wells Fargo, the collateral agreement dated July 18, 2022, the ADVA domestic collateral agreement dated June 4, 2024, the

guaranty agreement dated July 18, 2022 and the ADVA guaranty agreement dated June 4, 2024 and all principal amounts under the Former Credit Agreement were repaid.