| SC 13G | 2015-02-13 | FMR LLC | COGENT COMMUNICATIONS HOLDINGS, INC. | 3,542,906 | 7.7% | EDGAR |
| SC 13G/A | 2015-02-12 | Sarbit Advisory Services Inc. | COGENT COMMUNICATIONS HOLDINGS, INC. | 0 | 0.0% | EDGAR |
| SC 13G/A | 2015-02-11 | VANGUARD GROUP INC | COGENT COMMUNICATIONS HOLDINGS, INC. | 2,929,861 | 6.3% | EDGAR |
| SC 13G/A | 2015-02-11 | COLUMBIA WANGER ASSET MANAGEMENT LLC | COGENT COMMUNICATIONS HOLDINGS, INC. | 2,318,200 | 5.1% | EDGAR |
| SC 13G/A | 2015-02-09 | JENNISON ASSOCIATES LLC | COGENT COMMUNICATIONS HOLDINGS, INC. | 1,052,611 | 2.3% | EDGAR |
| SC 13G/A | 2015-02-09 | BlackRock Inc. | COGENT COMMUNICATIONS HOLDINGS, INC. | 2,525,391 | 5.5% | EDGAR |
| SC 13G/A | 2015-02-02 | PRUDENTIAL FINANCIAL INC | COGENT COMMUNICATIONS HOLDINGS, INC. | 1,059,800 | 2.3% | EDGAR |
| SC 13G/A | 2014-02-14 | FMR LLC | COGENT COMMUNICATIONS GROUP INC | 845,516 | 1.8% | EDGAR |
| SC 13G/A | 2014-02-14 | FRONTIER CAPITAL MANAGEMENT CO LLC | COGENT COMMUNICATIONS GROUP INC | 4,457,850 | 9.4% | EDGAR |
| SC 13G/A | 2014-02-12 | VANGUARD GROUP INC | COGENT COMMUNICATIONS GROUP INC | 2,796,725 | 5.9% | EDGAR |
| SC 13G | 2014-02-12 | Sarbit Advisory Services Inc. | COGENT COMMUNICATIONS GROUP INC | 3,135,135 | 6.6% | EDGAR |
| SC 13G | 2014-02-06 | JENNISON ASSOCIATES LLC | COGENT COMMUNICATIONS GROUP INC | 2,639,615 | 5.6% | EDGAR |
| SC 13G | 2014-02-05 | PRUDENTIAL FINANCIAL INC | COGENT COMMUNICATIONS GROUP INC | 2,645,604 | 5.6% | EDGAR |
| SC 13G/A | 2014-01-28 | BlackRock Inc. | COGENT COMMUNICATIONS GROUP INC | 2,651,264 | 5.6% | EDGAR |
| SC 13G/A | 2013-02-14 | FMR LLC | COGENT COMMUNICATIONS GROUP INC | 2,697,476 | 5.7% | EDGAR |
| SC 13G/A | 2013-02-14 | COLUMBIA WANGER ASSET MANAGEMENT LLC | COGENT COMMUNICATIONS GROUP INC | 10 | - | EDGAR |
| SC 13G/A | 2013-02-14 | FRONTIER CAPITAL MANAGEMENT CO LLC | COGENT COMMUNICATIONS GROUP INC | 3,691,002 | 7.8% | EDGAR |
| SC 13G | 2013-02-14 | Sarbit Advisory Services Inc. | COGENT COMMUNICATIONS GROUP INC | 2,757,602 | 5.8% | EDGAR |
| SC 13G/A | 2013-02-12 | VANGUARD GROUP INC | COGENT COMMUNICATIONS GROUP INC | 2,764,455 | 5.8% | EDGAR |
| SC 13G/A | 2013-02-08 | BlackRock Inc. | COGENT COMMUNICATIONS GROUP INC | 2,490,231 | 5.3% | EDGAR |