Adtran's stock plummeted 21.02% during intraday trading on Tuesday, marking a sharp reversal for the networking equipment provider.

The steep decline followed the company's release of its first quarter 2026 financial results. While Adtran reported adjusted earnings per share of $0.14, beating analyst expectations of $0.09, and revenue of $286.1 million that slightly exceeded estimates, the company posted a GAAP diluted loss per share of $0.01 for the quarter.

Investor disappointment appears to be driven by the GAAP loss despite the adjusted earnings beat, coupled with the company's second quarter revenue guidance range of $283 million to $303 million. The stock had also seen significant gains prior to the report, rising 46.7% during the quarter and 112.3% year-to-date, potentially leading to profit-taking on the mixed results.