| Type | Filed | Filer | Subject | Shares Owned | Percent Owned | |
|---|---|---|---|---|---|---|
| SC 13G/A | 2019-01-31 | BlackRock Inc. | TETRA TECH INC | 8,557,320 | 15.5% | EDGAR |
| SC 13G/A | 2018-08-08 | VANGUARD GROUP INC | TETRA TECH INC | 5,546,168 | 10.0% | EDGAR |
| SC 13G/A | 2018-02-12 | VANGUARD GROUP INC | TETRA TECH INC | 5,210,796 | 9.4% | EDGAR |
| SC 13G/A | 2018-02-09 | DIMENSIONAL FUND ADVISORS LP | TETRA TECH INC | 2,887,748 | 5.2% | EDGAR |
| SC 13G/A | 2018-01-19 | BlackRock Inc. | TETRA TECH INC | 7,323,999 | 13.1% | EDGAR |
| SC 13G/A | 2017-02-10 | VANGUARD GROUP INC | TETRA TECH INC | 4,910,049 | 8.6% | EDGAR |
| SC 13G | 2017-02-09 | DIMENSIONAL FUND ADVISORS LP | TETRA TECH INC | 3,242,303 | 5.7% | EDGAR |
| SC 13G/A | 2017-01-17 | BlackRock Inc. | TETRA TECH INC | 7,446,086 | 13.0% | EDGAR |
| SC 13G/A | 2016-04-08 | BlackRock Inc. | TETRA TECH INC | 5,910,900 | 10.1% | EDGAR |
| SC 13G/A | 2016-02-10 | VANGUARD GROUP INC | TETRA TECH INC | 4,240,003 | 7.2% | EDGAR |
| SC 13G | 2016-02-09 | DIMENSIONAL FUND ADVISORS LP | TETRA TECH INC | 3,512,565 | 6.0% | EDGAR |
| SC 13G/A | 2016-01-27 | BlackRock Inc. | TETRA TECH INC | 5,764,294 | 9.8% | EDGAR |
| SC 13G/A | 2015-08-12 | NORGES BANK | TETRA TECH INC | 2,946,426 | 4.9% | EDGAR |
| SC 13G/A | 2015-02-10 | VANGUARD GROUP INC | TETRA TECH INC | 4,131,331 | 6.6% | EDGAR |
| SC 13G | 2015-02-09 | NORGES BANK | TETRA TECH INC | 3,111,518 | 5.0% | EDGAR |
| SC 13G/A | 2015-01-15 | BlackRock Inc. | TETRA TECH INC | 5,711,946 | 9.1% | EDGAR |
| SC 13G/A | 2014-02-12 | VANGUARD GROUP INC | TETRA TECH INC | 3,865,735 | 6.0% | EDGAR |
| SC 13G/A | 2014-01-30 | BlackRock Inc. | TETRA TECH INC | 5,932,132 | 9.2% | EDGAR |
| SC 13G/A | 2013-02-14 | BAMCO INC /NY/ | TETRA TECH INC | 1,257,600 | 1.8% | EDGAR |
| SC 13G/A | 2013-02-11 | VANGUARD GROUP INC | TETRA TECH INC | 3,806,920 | 6.0% | EDGAR |