Form 4 Filing for Alkermes plc.

This filing details significant transactions by Brian P. McKeon, a director at Alkermes plc. On May 20, 2026, McKeon was granted 11,538 non-qualified stock options and 5,409 restricted stock units. The options have an exercise price of $36.98 and expire on May 20, 2036. The RSUs vest on the one-year anniversary of the grant date or the next annual general meeting. On May 21, 2026, 6,142 RSUs vested and were disposed of. In a separate non-derivative transaction on the same day, McKeon acquired 6,142 ordinary shares and disposed of 1,475 ordinary shares at $36.95 per share. Following these transactions, McKeon directly holds 38,536 ordinary shares and indirectly holds 10,000 ordinary shares through the Brian P. McKeon Trust.