| SC 13D/A | 2022-06-03 | KOSS JOHN C JR | KOSS CORP | 270,176 | 3.0% | EDGAR |
| SC 13D/A | 2022-06-03 | KOSS MICHAEL J | KOSS CORP | 4,113,410 | 45.0% | EDGAR |
| SC 13D/A | 2021-09-08 | KOSS JOHN C JR | KOSS CORP | 2,962,810 | 32.5% | EDGAR |
| SC 13D/A | 2021-09-08 | KOSS MICHAEL J | KOSS CORP | 4,113,410 | 44.0% | EDGAR |
| SC 13D/A | 2021-03-16 | KOSS JOHN C JR | KOSS CORP | 3,024,187 | 35.5% | EDGAR |
| SC 13D/A | 2021-03-16 | KOSS MICHAEL J | KOSS CORP | 4,072,700 | 47.8% | EDGAR |
| SC 13D/A | 2021-02-12 | KOSS MICHAEL J | KOSS CORP | 4,240,822 | 50.5% | EDGAR |
| SC 13G/A | 2021-02-11 | PRINCIPAL FINANCIAL GROUP INC | KOSS CORP | 394,043 | 5.3% | EDGAR |
| SC 13D/A | 2021-02-10 | KOSS JOHN C JR | KOSS CORP | 3,128,187 | 37.3% | EDGAR |
| SC 13D/A | 2021-02-10 | Koss Michael J Jr | KOSS CORP | 4,240,822 | 50.5% | EDGAR |
| SC 13G/A | 2020-02-11 | PRINCIPAL FINANCIAL GROUP INC | KOSS CORP | 394,258 | 5.3% | EDGAR |
| SC 13G/A | 2019-01-31 | PRINCIPAL FINANCIAL GROUP INC | KOSS CORP | 421,773 | 5.7% | EDGAR |
| SC 13G/A | 2018-02-07 | PRINCIPAL FINANCIAL GROUP INC | KOSS CORP | 475,528 | 6.4% | EDGAR |
| SC 13G/A | 2017-02-10 | PRINCIPAL FINANCIAL GROUP INC | KOSS CORP | 483,015 | 6.5% | EDGAR |
| SC 13G/A | 2016-01-22 | PRINCIPAL FINANCIAL GROUP INC | KOSS CORP | 503,488 | 6.8% | EDGAR |
| SC 13G/A | 2015-02-13 | PRINCIPAL FINANCIAL GROUP INC | KOSS CORP | 543,283 | 7.4% | EDGAR |
| SC 13G | 2014-01-31 | PRINCIPAL FINANCIAL GROUP INC | KOSS CORP | 568,106 | 7.7% | EDGAR |
| SC 13D | 2013-10-15 | KOSS MICHAEL J | KOSS CORP | 2,861,569 | 38.7% | EDGAR |
| SC 13D | 2013-10-15 | Koss Nancy L | KOSS CORP | 857,949 | 11.6% | EDGAR |
| SC 13D | 2013-10-15 | KOSS JOHN C JR | KOSS CORP | 1,615,654 | 21.9% | EDGAR |