San Diego, California--(Newsfile Corp. - July 22, 2026) - Johnson Fistel, PLLP is investigating ADTRAN Holdings, Inc. (NASDAQ: ADTN) on behalf of investors who suffered losses and whether those losses may be recoverable under federal securities laws.

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On July 22, 2026, ADTRAN announced preliminary second-quarter 2026 results indicating that non-GAAP operating margins would be significantly below its previously issued guidance. The Company attributed the shortfall to a project delay involving a single customer and higher-than-expected component and freight costs, which negatively impacted profitability. Following the announcement, ADTRAN's stock declined sharply in early morning trading.

Johnson Fistel is investigating whether ADTRAN failed to timely disclose customer project delays and increasing cost pressures that materially affected its second-quarter financial performance. The investigation focuses on whether management knew, or should have known, that these adverse conditions had materially reduced revenue and operating margins, making the Company's previously issued guidance unattainable, yet failed to timely disclose this information to investors.

If you purchased ADTRAN securities and suffered losses, or possess information that may assist this investigation, please contact Johnson Fistel to discuss your legal rights.

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For more information, contact Jim Baker at jimb@johnsonfistel.com or (619) 814-4471. There is no cost or obligation to you.

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Johnson Fistel, PLLP is a nationally recognized shareholder rights law firm with offices in California, New York, Georgia, Idaho, and Colorado. The firm represents individual and institutional investors in shareholder derivative and securities class action lawsuits. We also extend our services to foreign investors who have purchased on U.S. exchanges. For more information about the firm and how we may be able to help you recover your losses, please visit www.johnsonfistel.com.

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Source: Johnson Fistel, PLLP