| George Kaiser Family Foundation | 7,854,167 | $298.4m | 28.7% |
| WELLINGTON MANAGEMENT GROUP LLP | 3,339,759 | $126.9m | 0.0% |
| BlackRock, Inc. | 2,014,640 | $76.5m | 0.0% |
| Copeland Capital Management, LLC | 1,973,585 | $75.0m | 1.5% |
| VANGUARD PORTFOLIO MANAGEMENT LLC | 1,230,722 | $46.8m | 0.0% |
| TORTOISE CAPITAL ADVISORS, L.L.C. | 1,166,178 | $44.3m | 0.5% |
| VANGUARD CAPITAL MANAGEMENT LLC | 994,364 | $37.8m | 0.0% |
| TimesSquare Capital Management, LLC | 950,222 | $36.1m | 0.5% |
| Ranger Investment Management, L.P. | 912,300 | $34.7m | 2.2% |
| KAYNE ANDERSON CAPITAL ADVISORS LP | 664,577 | $25.2m | 0.5% |
| CUSHING ASSET MANAGEMENT, LP dba NXG INVESTMENT MANAGEMENT | 650,000 | $24.7m | 1.1% |
| GEODE CAPITAL MANAGEMENT, LLC | 616,604 | $23.4m | 0.0% |
| STATE STREET CORP | 572,420 | $21.7m | 0.0% |
| DIMENSIONAL FUND ADVISORS LP | 514,252 | $19.5m | 0.0% |
| EMERALD ADVISERS, LLC | 485,260 | $18.4m | 0.4% |
| FMR LLC | 480,346 | $18.2m | 0.0% |
| D. E. Shaw & Co., Inc. | 392,792 | $14.9m | 0.0% |
| Yaupon Capital Management LP | 390,353 | $14.8m | 0.3% |
| NEUBERGER BERMAN GROUP LLC | 374,392 | $14.2m | 0.0% |
| Russell Investments Group, Ltd. | 343,449 | $13.0m | 0.0% |
| NORTHERN TRUST CORP | 337,703 | $12.8m | 0.0% |
| MORGAN STANLEY | 337,348 | $12.8m | 0.0% |
| MIRAE ASSET GLOBAL ETFS HOLDINGS Ltd. | 336,084 | $12.8m | 0.0% |
| EMERALD MUTUAL FUND ADVISERS TRUST | 299,991 | $11.4m | 0.4% |
| GOLDMAN SACHS GROUP INC | 289,600 | $11.0m | 0.0% |