| Jan 1, 2019 AForm 4 → | Jan 3, 1:37 pm EST | COGENT COMMUNICATIONS HOLDINGS, INC.CCOI | 1,750 | — | — | 22,861 | — | plan? |
| Nov 8, 2018 SForm 4 → | Nov 9, 3:54 pm EST | COGENT COMMUNICATIONS HOLDINGS, INC.CCOI | 2,500 | $51.01 | $127,523 | 21,111 | −10.6% | plan? |
| Oct 1, 2018 AForm 4 → | Oct 1, 5:14 pm EDT | COGENT COMMUNICATIONS HOLDINGS, INC.CCOI | 1,750 | — | — | 23,611 | — | plan? |
| Jul 1, 2018 AForm 4 → | Jul 3, 1:17 pm EDT | COGENT COMMUNICATIONS HOLDINGS, INC.CCOI | 1,750 | — | — | 21,861 | — | plan? |
| Apr 1, 2018 AForm 4 → | Apr 2, 4:30 pm EDT | COGENT COMMUNICATIONS HOLDINGS, INC.CCOI | 1,750 | — | — | 20,111 | — | plan? |
| Mar 16, 2018 SForm 4 → | Mar 16, 4:46 pm EDT | COGENT COMMUNICATIONS HOLDINGS, INC.CCOI | 1,700 | $43.60 | $74,120 | 18,361 | −8.47% | plan? |
| Jan 1, 2018 AForm 4 → | Jan 3, 9:18 am EST | COGENT COMMUNICATIONS HOLDINGS, INC.CCOI | 1,750 | — | — | 20,061 | — | plan? |
| Dec 15, 2017 SForm 4 → | Dec 15, 4:14 pm EST | COGENT COMMUNICATIONS HOLDINGS, INC.CCOI | 2,125 | $47.02 | $99,921 | 18,311 | −10.4% | plan? |
| Oct 1, 2017 AForm 4 → | Oct 3, 4:59 pm EDT | COGENT COMMUNICATIONS HOLDINGS, INC.CCOI | 1,750 | — | — | 20,436 | — | plan? |
| Sep 14, 2017 SForm 4 → | Sep 15, 1:57 pm EDT | COGENT COMMUNICATIONS HOLDINGS, INC.CCOI | 1,616 | $45.97 | $74,288 | 18,686 | −7.96% | plan? |
| Sep 1, 2017 SForm 4 → | Sep 5, 4:55 pm EDT | COGENT COMMUNICATIONS HOLDINGS, INC.CCOI | 1,100 | $46.69 | $51,359 | 20,302 | −5.14% | plan? |
| Jul 1, 2017 AForm 4 → | Jul 5, 1:27 pm EDT | COGENT COMMUNICATIONS HOLDINGS, INC.CCOI | 1,750 | — | — | 21,402 | — | plan? |
| Jun 16, 2017 SForm 4 → | Jun 19, 11:55 am EDT | COGENT COMMUNICATIONS HOLDINGS, INC.CCOI | 2,383 | $40.15 | $95,677 | 19,652 | −10.8% | plan? |
| May 3, 2017 AForm 4 → | May 3, 4:10 pm EDT | COGENT COMMUNICATIONS HOLDINGS, INC.CCOI | 1,750 | — | — | 22,035 | — | plan? |
| Mar 14, 2017 SForm 4 → | Mar 15, 4:25 pm EDT | COGENT COMMUNICATIONS HOLDINGS, INC.CCOI | 2,369 | $40.51 | $95,968 | 20,285 | −10.5% | plan? |
| Feb 27, 2017 SForm 4 → | Feb 28, 9:52 am EST | COGENT COMMUNICATIONS HOLDINGS, INC.CCOI | 2,450 | $42.40 | $103,880 | 22,654 | −9.76% | plan? |
| Jan 1, 2017 AForm 4 → | Jan 4, 10:52 am EST | COGENT COMMUNICATIONS HOLDINGS, INC.CCOI | 1,750 | — | — | 25,104 | — | plan? |
| Oct 1, 2016 AForm 4 → | Oct 4, 1:26 pm EDT | COGENT COMMUNICATIONS HOLDINGS, INC.CCOI | 1,875 | — | — | 23,354 | — | plan? |
| Sep 16, 2016 SForm 4 → | Sep 19, 11:18 am EDT | COGENT COMMUNICATIONS HOLDINGS, INC.CCOI | 2,822 | $35.57 | $100,379 | 21,479 | −11.6% | plan? |
| Jul 1, 2016 AForm 4 → | Jul 5, 10:26 am EDT | COGENT COMMUNICATIONS HOLDINGS, INC.CCOI | 1,875 | — | — | 24,301 | — | plan? |
| Apr 1, 2016 AForm 4 → | Apr 4, 12:34 pm EDT | COGENT COMMUNICATIONS HOLDINGS, INC.CCOI | 1,875 | — | — | 22,426 | — | plan? |
| Mar 17, 2016 SForm 4 → | Mar 21, 9:31 am EDT | COGENT COMMUNICATIONS HOLDINGS, INC.CCOI | 3,600 | $37.44 | $134,784 | 20,551 | −14.9% | plan? |
| Jan 1, 2016 AForm 4 → | Jan 5, 3:12 pm EST | COGENT COMMUNICATIONS HOLDINGS, INC.CCOI | 1,875 | — | — | 24,151 | — | plan? |
| Oct 1, 2015 AForm 4 → | Oct 2, 12:27 pm EDT | COGENT COMMUNICATIONS HOLDINGS, INC.CCOI | 1,875 | — | — | 22,276 | — | plan? |
| Jul 1, 2015 AForm 4 → | Jul 1, 4:36 pm EDT | COGENT COMMUNICATIONS HOLDINGS, INC.CCOI | 1,875 | — | — | 20,401 | — | plan? |
| Jun 9, 2015 SForm 4 → | Jun 10, 4:34 pm EDT | COGENT COMMUNICATIONS HOLDINGS, INC.CCOI | 3,200 | $30.56 | $97,789 | 18,526 | −14.7% | plan? |
| Apr 1, 2015 AForm 4 → | Apr 1, 4:11 pm EDT | COGENT COMMUNICATIONS HOLDINGS, INC.CCOI | 1,875 | — | — | 21,726 | — | plan? |
| Jan 1, 2015 AForm 4 → | Jan 2, 4:04 pm EST | COGENT COMMUNICATIONS HOLDINGS, INC.CCOI | 1,875 | — | — | 19,851 | — | plan? |