| 2006-11-14 | Sale | Cogent Communications Holdings, Inc. CCOI | director | 2.2M 4.0811% | $14.64 | $32.21M | +49.57% | |
| 2006-06-07 | Sale | Cogent Communications Holdings, Inc. CCOI | 1.8M 3.6754% | $8.53 | $15.35M | +73% | ||
| 2003-07-31 | Cogent Communications Holdings, Inc. CCOI | 19,665 – | $491.48 | $9.66M | -27.27% |