| Jun 19, 2018 SForm 4 → | Jun 19, 4:19 pm EDT | COGENT COMMUNICATIONS HOLDINGS, INC.CCOI | 2,100 | $54.76 | $114,988 | 49,640 | −4.06% | plan? |
| Jun 15, 2018 SForm 4 → | Jun 18, 11:32 am EDT | COGENT COMMUNICATIONS HOLDINGS, INC.CCOI | 3,000 | $53.78 | $161,333 | 51,740 | −5.48% | plan? |
| Jun 6, 2018 SForm 4 → | Jun 6, 3:57 pm EDT | COGENT COMMUNICATIONS HOLDINGS, INC.CCOI | 3,000 | $52.67 | $157,997 | 54,740 | −5.20% | plan? |
| Feb 21, 2018 AForm 4 → | Feb 22, 4:50 pm EST | COGENT COMMUNICATIONS HOLDINGS, INC.CCOI | 9,600 | — | — | 57,740 | — | plan? |
| Oct 26, 2017 GForm 4 → | Oct 26, 3:36 pm EDT | COGENT COMMUNICATIONS HOLDINGS, INC.CCOI | 1,000 | — | — | 48,140 | — | plan? |
| Sep 29, 2017 GForm 4 → | Sep 29, 1:32 pm EDT | COGENT COMMUNICATIONS HOLDINGS, INC.CCOI | 1,200 | — | — | 49,140 | — | plan? |
| Sep 13, 2017 SForm 4 → | Sep 14, 5:56 pm EDT | COGENT COMMUNICATIONS HOLDINGS, INC.CCOI | 4,000 | $46.62 | $186,492 | 50,340 | −7.36% | plan? |
| Sep 1, 2017 SForm 4 → | Sep 1, 4:02 pm EDT | COGENT COMMUNICATIONS HOLDINGS, INC.CCOI | 3,000 | $46.86 | $140,578 | 54,340 | −5.23% | plan? |
| Aug 30, 2017 SForm 4 → | Aug 31, 4:04 pm EDT | COGENT COMMUNICATIONS HOLDINGS, INC.CCOI | 2,000 | $45.78 | $91,555 | 57,340 | −3.37% | plan? |
| May 3, 2017 AForm 4 → | May 3, 4:20 pm EDT | COGENT COMMUNICATIONS HOLDINGS, INC.CCOI | 9,600 | — | — | 59,340 | — | plan? |
| Apr 24, 2017 SForm 4 → | Apr 25, 6:21 pm EDT | COGENT COMMUNICATIONS HOLDINGS, INC.CCOI | 3,000 | $44.84 | $134,525 | 49,740 | −5.69% | plan? |
| Apr 7, 2017 SForm 4 → | Apr 10, 10:49 am EDT | COGENT COMMUNICATIONS HOLDINGS, INC.CCOI | 2,000 | $43.77 | $87,535 | 52,740 | −3.65% | plan? |
| Mar 24, 2017 SForm 4 → | Mar 24, 5:23 pm EDT | COGENT COMMUNICATIONS HOLDINGS, INC.CCOI | 2,000 | $42.79 | $85,580 | 54,740 | −3.52% | plan? |
| Jan 4, 2017 SForm 4 → | Jan 4, 5:54 pm EST | COGENT COMMUNICATIONS HOLDINGS, INC.CCOI | 1,000 | $42.53 | $42,526 | 56,740 | −1.73% | plan? |
| Dec 16, 2016 GForm 4 → | Dec 19, 11:42 am EST | COGENT COMMUNICATIONS HOLDINGS, INC.CCOI | 1,000 | — | — | 57,740 | — | plan? |
| Jul 8, 2016 SForm 4 → | Jul 11, 12:35 pm EDT | COGENT COMMUNICATIONS HOLDINGS, INC.CCOI | 1,000 | $41.53 | $41,530 | 58,740 | −1.67% | plan? |
| Jun 8, 2016 SForm 4 → | Jun 8, 6:02 pm EDT | COGENT COMMUNICATIONS HOLDINGS, INC.CCOI | 1,000 | $40.93 | $40,929 | 59,740 | −1.65% | plan? |
| May 31, 2016 SForm 4 → | May 31, 4:42 pm EDT | COGENT COMMUNICATIONS HOLDINGS, INC.CCOI | 1,000 | $39.90 | $39,900 | 60,740 | −1.62% | plan? |
| May 4, 2016 AForm 4 → | May 5, 11:10 am EDT | COGENT COMMUNICATIONS HOLDINGS, INC.CCOI | 12,000 | — | — | 61,740 | — | plan? |
| Apr 1, 2016 SForm 4 → | Apr 4, 2:33 pm EDT | COGENT COMMUNICATIONS HOLDINGS, INC.CCOI | 4,000 | $39.83 | $159,325 | 49,740 | −7.44% | plan? |
| Mar 29, 2016 SForm 4 → | Mar 29, 4:37 pm EDT | COGENT COMMUNICATIONS HOLDINGS, INC.CCOI | 1,400 | $38.60 | $54,038 | 53,740 | −2.54% | plan? |
| Mar 11, 2016 SForm 4 → | Mar 14, 5:48 pm EDT | COGENT COMMUNICATIONS HOLDINGS, INC.CCOI | 3,000 | $37.02 | $111,050 | 55,140 | −5.16% | plan? |
| Dec 18, 2015 GForm 4 → | Dec 18, 11:23 am EST | COGENT COMMUNICATIONS HOLDINGS, INC.CCOI | 1,000 | — | — | 58,140 | — | plan? |
| Aug 25, 2015 MForm 4 → | Aug 25, 3:38 pm EDT | COGENT COMMUNICATIONS HOLDINGS, INC.CCOI | 3,800 | $4.88 | $18,544 | 59,140 | — | plan? |
| Feb 11, 2015 SForm 4 → | Feb 13, 10:02 am EST | COGENT COMMUNICATIONS HOLDINGS, INC.CCOI | 435 | $40.01 | $17,405 | 55,340 | −0.78% | plan? |
| Feb 10, 2015 SForm 4 → | Feb 10, 6:11 pm EST | COGENT COMMUNICATIONS HOLDINGS, INC.CCOI | 3,165 | $40.01 | $126,628 | 55,775 | −5.37% | plan? |
| Jan 22, 2015 SForm 4 → | Jan 23, 3:05 pm EST | COGENT COMMUNICATIONS HOLDINGS, INC.CCOI | 5,000 | $38.08 | $190,414 | 58,940 | −7.82% | plan? |
| Jan 20, 2015 SForm 4 → | Jan 21, 4:21 pm EST | COGENT COMMUNICATIONS HOLDINGS, INC.CCOI | 4,000 | $37.09 | $148,363 | 63,940 | −5.89% | plan? |