| Marxe Austin W & Greenhouse David M10% owner · 2 transactions | — | 15.02M†as of Feb 2013 | — | — | 7.00M |
| Dte Energy Co10% owner · 4 transactions | — | 8.05Mas of Dec 2007 | 11.8K | — | — |
| Axane SaDirector · 2 transactions | — | 6.39Mas of Aug 2015 | 1.61M | — | 6.39M |
| Branton LTD +5 co-filers10% owner · 130 transactions | — | 5.12Mas of Feb 2008 | — | 506.0K | — |
| Branton LTD +5 co-filers10% owner · 2 transactions | — | 4.55Mas of Jun 2006 | — | 1.84M | — |
| JSC INTER RAO Capital10% owner · 2 transactions | — | 4.46Mas of Sep 2013 | — | — | — |
| Joint Stock Co INTER RAO UES10% owner · 1 transaction | — | 4.46Mas of Sep 2013 | — | — | — |
| Middleton Paul BCFO & Executive VP · 41 transactions | — | 3.01M† | 3.98M | 1.00M | 1.71M |
| FiveT Capital Holding AGDirector · 6 transactions | — | 2.87M†as of Nov 2020 | — | — | 2.87M |
| McNamee George CDirector · 132 transactions | — | 1.17M† | 1.37M | 500.1K | 213.5K |
| Marsh AndrewDirector · 79 transactions | — | 975.3K† | 7.27M | 287.4K | 5.71M |
| Willis Gary KDirector · 95 transactions | — | 730.1K | 945.4K | — | 90.2K |
| Schmid KeithGM New Mkts & Pres New Prd Dv · 45 transactions | — | 521.0K†as of Oct 2023 | 2.73M | 14.0K | 2.02M |
| Kenausis GregoryDirector · 71 transactions | — | 510.4K | 625.4K | — | 115.0K |
| Schmidt KeithGM New Mkts & Pres New Prd Dv · 2 transactions | — | 462.8K†as of Dec 2022 | — | — | — |
| Crespo Jose LuisSee Remarks · 10 transactions | — | 419.4K† | 119.1K | 37.3K | 69.3K |
| Mindnich DavidEVP, Global Manufacturing · 1 transaction | — | 406.5K†as of Jan 2024 | — | — | — |
| Helmer Maureen ODirector · 112 transactions | — | 361.3K | 962.0K | 5.0K | 480.5K |
| Conway Gerard L JRGen. Coun, Corp Sec., Exec. VP · 71 transactions | — | 342.1K†as of May 2025 | 2.08M | — | 1.54M |
| Haycraft BenjaminCSO & GM EMEA · 7 transactions | — | 333.8K | — | — | 111.0K |
| Corless Adrian JChief Technology Officer · 1 transaction | — | 296.9Kas of Jul 2013 | — | 20.0K | — |
| Hansen Erik JVP & GM, Motive Power Division · 2 transactions | — | 296.3Kas of Jul 2013 | — | 10.0K | — |
| Hoefelmann Dirk OleGM, Electrolyzers & Exec VP · 2 transactions | — | 281.6K†as of Apr 2023 | — | — | — |
| Bonney Mark JDirector · 14 transactions | — | 262.8K | 262.8K | — | — |
| Joggerst PatrickDirector · 14 transactions | — | 245.5K | 245.5K | — | — |
| Mahtani KavitaDirector · 20 transactions | — | 239.8K | 239.8K | — | — |
| Roth Johannes MinhoDirector · 48 transactions | — | 234.6Kas of Jul 2022 | 234.6K | — | 2.87M |
| Hull Martin DanielCorporate Controller and CAO · 47 transactions | — | 226.0K†as of May 2025 | 614.2K | — | 343.6K |
| Garberding LarryDirector · 44 transactions | — | 197.7Kas of Apr 2017 | 316.7K | — | 3.0K |
| Shrestha Sanjay KCSO & GM, Energy Solutions · 14 transactions | — | 168.2K†as of Oct 2023 | 375.0K | — | 90.5K |
| Angle Colin MDirector · 9 transactions | — | 149.5K | 149.5K | — | — |
| Schneider Lucas PDirector · 35 transactions | — | 135.3Kas of Apr 2023 | 145.8K | — | 10.5K |
| Anderson Gerald AChief Financial Officer · 6 transactions | — | 132.2Kas of Feb 2010 | 115.9K | — | — |
| Hickey Douglas TDirector · 42 transactions | — | 109.9Kas of Jul 2018 | 254.3K | — | — |
| Graves Gregory BDirector · 12 transactions | — | 83.4Kas of May 2019 | 114.8K | — | 31.3K |
| Silver Jonathan MDirector · 31 transactions | — | 75.7Kas of Jul 2023 | 196.4K | — | 120.6K |
| Sperry Mark AVP & GM, Continuous Power Div. · 14 transactions | — | 67.4Kas of Mar 2010 | 107.9K | — | 74.7K |
| Miroshnichenko EvgenyDirector · 7 transactions | — | 62.3Kas of Jul 2014 | 62.3K | — | — |
| Grant J DouglasDirector · 10 transactions | — | 57.4Kas of Jan 2009 | 31.8K | — | — |
| Drazan Jeffrey MDirector · 9 transactions | — | 53.5Kas of Jan 2011 | 53.5K | — | — |
| Silvestri Gregory AChief Operating Officer · 4 transactions | — | 51.6Kas of Feb 2007 | 31.8K | — | 2.8K |
| Rasskazov EvgenyDirector · 3 transactions | — | 51.3Kas of Jul 2013 | 51.3K | — | — |
| Reid ChrisVice President · 4 transactions | — | 48.4Kas of Dec 2008 | 61.9K | — | — |
| Elter John FVP Res. & System Architecture · 3 transactions | — | 42.8Kas of Feb 2007 | 16.1K | — | 1.3K |
| Air Liquide Investissements d'Avenir et de DemonstrationDirector · 31 transactions | — | 39.3Kas of Sep 2017 | 192.1K | — | 5.69M |
| Neumann David AChief Financial Officer · 2 transactions | — | 35.3Kas of Feb 2006 | 22.8K | — | — |
| Woicke PeterDirector · 10 transactions | — | 33.6Kas of Jan 2009 | 33.6K | — | — |
| Pontone XavierDirector · 14 transactions | — | 31.2Kas of Apr 2017 | 31.2K | — | — |
| Gross Joel DDirector · 11 transactions | — | 28.4Kas of Apr 2009 | 28.4K | — | — |
| Bua Jean ADirector · 7 transactions | — | 22.7Kas of Jul 2023 | 22.7K | — | — |
| Millington Joseph MVP Human Resources · 4 transactions | — | 16.9Kas of Apr 2008 | 22.0K | — | 5.1K |
| Bucknam Allen KVP Strategy and Business Dev · 2 transactions | — | 14.0Kas of Oct 2007 | — | — | 6.5K |
| Batekhin SergeyDirector · 9 transactions | — | 12.1Kas of Oct 2008 | 12.1K | — | — |
| McGuire Michael E JrDirector · 4 transactions | — | 11.8Kas of Apr 2009 | 11.8K | — | — |
| Rosenblum LisaDirector · 9 transactions | — | 11.4Kas of Oct 2008 | 11.4K | — | — |
| Polikarpov SergeyDirector · 8 transactions | — | 11.2Kas of Jul 2008 | 11.2K | — | — |
| Pivnyuk Dennis VDirector · 3 transactions | — | 9.9Kas of Apr 2009 | 9.9K | — | — |
| Dimitri AndrewDirector · 3 transactions | — | 7.4Kas of Apr 2009 | 7.4K | — | — |
| Harriman KimDirector · 7 transactions | — | 6.5Kas of Jul 2022 | 6.5K | — | — |
| Johnson Bradley HVP Customer Operations · 1 transaction | — | 5.0Kas of Feb 2008 | — | — | 5.0K |
| Branton LTD +2 co-filers10% owner · 1 transaction | — | 0as of Dec 2008 | — | — | 5.13M |
| OJSC Third Generation Co of the Wholesale Electricity Market10% owner · 1 transaction | — | 0as of Sep 2012 | — | — | 4.46M |
| Prokhorov Mikhail D10% owner · 1 transaction | — | 0as of Apr 2008 | — | — | 640.8K |
| Greenberg AllanVice President, Sales · 1 transaction | — | 0as of Oct 2006 | 15.0K | — | — |
| MMC Norlisk Nickel10% owner · 1 transaction | — | 0as of Mar 2011 | — | — | — |
| Nelson Jean MChief Financial Officer · 1 transaction | — | 0as of Nov 2006 | 24.0K | — | — |