| SC 13D/A | 2017-04-03 | DINGER CARL W III | Perma-Pipe International Holdings, Inc. | - | 5.9% | EDGAR |
| SC 13G/A | 2017-02-14 | PERRITT CAPITAL MANAGEMENT INC | MFRI INC | 0 | 0.0% | EDGAR |
| SC 13G/A | 2017-02-09 | DIMENSIONAL FUND ADVISORS LP | MFRI INC | 566,126 | 7.5% | EDGAR |
| SC 13G | 2017-01-27 | WELLS FARGO & COMPANY/MN | MFRI INC | 454,295 | 6.0% | EDGAR |
| SC 13D/A | 2017-01-19 | DINGER CARL W III | MFRI INC | - | 5.8% | EDGAR |
| SC 13D/A | 2017-01-09 | DINGER CARL W III | MFRI INC | - | 5.8% | EDGAR |
| SC 13D | 2016-10-19 | DINGER CARL W III | MFRI INC | - | 5.6% | EDGAR |
| SC 13G/A | 2016-02-09 | DIMENSIONAL FUND ADVISORS LP | MFRI INC | 566,759 | 7.8% | EDGAR |
| SC 13G/A | 2016-02-04 | PERRITT CAPITAL MANAGEMENT INC | MFRI INC | 373,376 | 5.1% | EDGAR |
| SC 13G/A | 2015-02-18 | Wedbush Edward William | MFRI INC | 210,157 | 2.9% | EDGAR |
| SC 13G/A | 2015-02-13 | PERRITT CAPITAL MANAGEMENT INC | MFRI INC | 455,220 | 6.2% | EDGAR |
| SC 13G/A | 2015-02-05 | DIMENSIONAL FUND ADVISORS LP | MFRI INC | 581,382 | 8.0% | EDGAR |
| SC 13G/A | 2014-02-18 | WEDBUSH, Inc. | MFRI INC | 260,052 | 3.8% | EDGAR |
| SC 13G/A | 2014-02-14 | PERRITT CAPITAL MANAGEMENT INC | MFRI INC | 455,220 | 6.4% | EDGAR |
| SC 13G/A | 2014-02-10 | DIMENSIONAL FUND ADVISORS LP | MFRI INC | 569,038 | 8.0% | EDGAR |
| SC 13G/A | 2014-02-05 | BABSON CAPITAL MANAGEMENT LLC | MFRI INC | 0 | 0.0% | EDGAR |
| SC 13G/A | 2013-12-06 | HEARTLAND ADVISORS INC | MFRI INC | 329,315 | 4.7% | EDGAR |
| SC 13G/A | 2013-02-15 | WEDBUSH, Inc. | MFRI INC | 260,052 | 3.8% | EDGAR |
| SC 13G/A | 2013-02-11 | PERRITT CAPITAL MANAGEMENT INC | MFRI INC | 393,407 | 5.7% | EDGAR |
| SC 13G/A | 2013-02-11 | DIMENSIONAL FUND ADVISORS LP | MFRI INC | 557,703 | 8.1% | EDGAR |