| Filed | Form | Description | |
|---|---|---|---|
| 11/5/25 | DEF 14A | DEF 14A | → |
| 11/5/24 | DEF 14A | DEF 14A | → |
| 11/9/23 | DEF 14A | DEF 14A | → |
| 12/9/22 | DEFA14A | DEFINITIVE ADDITIONAL MATERIALS | → |
| 11/21/22 | DEF 14A | PROCY STATEMENT | → |
| 11/5/21 | DEFA14A | DEFA14A | → |
| ↓ | |||
| Filed | Form | Description | |
|---|---|---|---|
| 8/20/25 | 4 | 4 | → |
| 4/2/25 | 4 | OWNERSHIP DOCUMENT | → |
| 4/2/25 | 4 | OWNERSHIP DOCUMENT | → |
| 4/2/25 | 4 | OWNERSHIP DOCUMENT | → |
| 4/2/25 | 4 | OWNERSHIP DOCUMENT | → |
| 4/2/25 | 4 | OWNERSHIP DOCUMENT | → |
| ↓ | |||
Actinium is a chemical element; it has symbol Ac and atomic number 89. It was discovered by Friedrich Oskar Giesel in 1902, who gave it the name emanium; the element got its name by being wrongly identified with a substance André-Louis Debierne found in 1899 and called actinium.