Exhibit 99.1 FOR IMMEDIATE RELEASE Mercury Systems Reports Third Quarter Fiscal 2026 Results ANDOVER, Mass. May 5, 2026 Mercury Systems, Inc. (NASDAQ: MRCY, www.mrcy.com), reported operating results for the third quarter of fiscal year 2026, ended March 27, 2026. "We delivered third quarter fiscal 2026 results that were ahead of our expectations, with significant year-over-year growth in backlog, revenue, and adjusted EBITDA," said Bill Ballhaus, Mercury's Chairman and CEO. "Strong demand signals and solid ...