As of August 29, 2026, the three largest insider holders of HTO are Infrastructure Partners (Uk) Ltd. Atlas (TenPercentOwner, 4.62Mn shares), Infrastructure Partners (Uk) Ltd. Atlas (TenPercentOwner, 4.62Mn shares), Atlas Holdings Ltd Gip (TenPercentOwner, 4.58Mn shares).
| # | Insider | Position | Direct | Indirect | Total | Share of Insiders | Last Filed |
|---|---|---|---|---|---|---|---|
| 1 | Infrastructure Partners (Uk) Ltd. Atlas | TenPercentOwner | 4,615,265 | 0 | 4,615,265 | 48.2% | 13 Jul, 2026 |
| 2 | Atlas Holdings Ltd Gip | TenPercentOwner | 4,582,469 | 0 | 4,582,469 | 47.9% | 22 Apr, 2026 |
| 3 | Eric W Thornburg | President Ceo | 78,418 | 0 | 78,418 | 0.8% | 04 Mar, 2025 |
| 4 | Maureen P Westbrook | President Of Ctws | 40,590 | 0 | 40,590 | 0.4% | 30 Dec, 2022 |
| 5 | Andrew F Walters | Chief Executive Officer | 26,461 | 0 | 26,461 | 0.3% | 06 Jul, 2026 |
| 6 | Andrew Gere | President Of Sjwc | 25,410 | 0 | 25,410 | 0.3% | 02 Mar, 2023 |
| 7 | James Patrick Lynch | Chief Accounting Officer | 25,249 | 0 | 25,249 | 0.3% | 04 Nov, 2022 |
| 8 | Bruce A Hauk | President And Coo | 16,616 | 0 | 16,616 | 0.2% | 03 Mar, 2026 |
| 9 | A Kristen Johnson | Chief Administrative Officer | 14,565 | 0 | 14,565 | 0.2% | 03 Mar, 2026 |
| 10 | Megan Mattern | Cao, Pao And Controller | 13,631 | 0 | 13,631 | 0.1% | 03 Aug, 2026 |
| 11 | Willie D. Jr. Brown | Vp Gen Counsel | 13,554 | 0 | 13,554 | 0.1% | 03 Mar, 2026 |
| 12 | Tanya Moniz-Witten | President, San Jose Water Co. | 12,812 | 0 | 12,812 | 0.1% | 01 May, 2025 |
| 13 | Gregory P Landis | Director | 12,803 | 0 | 12,803 | 0.1% | 15 May, 2025 |
| 14 | Mary Ann Hanley | Director | 11,583 | 0 | 11,583 | 0.1% | 15 May, 2026 |
| 15 | Carol P Wallace | Director | 11,238 | 0 | 11,238 | 0.1% | 15 May, 2026 |
| 16 | Hunt Heather | Director | 11,238 | 0 | 11,238 | 0.1% | 15 May, 2026 |
| 17 | Ann P Kelly | Cfo And Treasurer | 9,976 | 0 | 9,976 | 0.1% | 06 Jul, 2026 |
| 18 | Rebecca A Klein | Director | 9,208 | 0 | 9,208 | 0.1% | 15 May, 2026 |
| 19 | Carl Guardino | Director | 9,139 | 0 | 9,139 | 0.1% | 15 May, 2026 |
| 20 | Denise L Kruger | Director | 6,923 | 0 | 6,923 | 0.1% | 15 May, 2026 |
| 21 | Wendy Avila-Walker | Vp Of Finance, Controller | 5,806 | 0 | 5,806 | 0.1% | 06 Jan, 2022 |
| 22 | Walter J. Bishop | Director | 5,353 | 0 | 5,353 | 0.1% | 29 Apr, 2022 |
| 23 | Craig J Patla | President Of Ctws | 5,200 | 0 | 5,200 | 0.1% | 04 Mar, 2025 |
| 24 | Mohammed G. Zerhouni | Svp Of Fin., Prin. Acct. Ofcr. | 3,567 | 0 | 3,567 | 0.0% | 05 Feb, 2024 |
| 25 | Katharine Armstrong | Director | 0 | 2,700 | 2,700 | 0.0% | 09 Dec, 2021 |
| 26 | Nick Orlando Rowe | Director | 2,452 | 0 | 2,452 | 0.0% | 15 May, 2026 |
| 27 | Daniel B. More | Director | 1,947 | 0 | 1,947 | 0.0% | 15 May, 2026 |
| 28 | Douwe Busschops | Chief Information Officer | 1,768 | 0 | 1,768 | 0.0% | 06 Jan, 2025 |
Each row is that insider’s most recently reported position, from Form 4 filings over the last 60 months — which is why this total does not tie to the quarterly series above, where a quarter counts only the insiders who filed in it. Shares held through a fund or institutional portfolio are counted on the institutional ownership page instead.
| Date | Insider | Position | Transaction | Shares | Price | Value | Shares Held After | Ownership |
|---|---|---|---|---|---|---|---|---|
| 30 Jul, 2026 | Megan Mattern | Cao, Pao And Controller | Disposed F | 1,154 | $61.97 | $71.51K | 13,631 | Direct |
| 07 Jul, 2026 | Infrastructure Partners (Uk) Ltd. Atlas | TenPercentOwner | Acquired P | 2,784 | $62.03 | $172.69K | 4,615,265 | Direct |
| 07 Jul, 2026 | Infrastructure Partners (Uk) Ltd. Atlas | TenPercentOwner | Acquired P | 2,784 | $62.03 | $172.69K | 4,615,265 | Direct |
| 01 Jul, 2026 | Andrew F Walters | Chief Executive Officer | Disposed D | 374 | $60.74 | $22.72K | 26,461 | Direct |
| 01 Jul, 2026 | Ann P Kelly | Cfo And Treasurer | Disposed F | 88 | $60.74 | $5.35K | 9,976 | Direct |
| 01 Jul, 2026 | Infrastructure Partners (Uk) Ltd. Atlas | TenPercentOwner | Disposed S | 1,686 | $60.74 | $102.40K | 4,610,349 | Direct |
| 01 Jul, 2026 | Infrastructure Partners (Uk) Ltd. Atlas | TenPercentOwner | Acquired P | 2,132 | $60.76 | $129.53K | 4,612,481 | Direct |
| 05 Jun, 2026 | Andrew F Walters | Chief Executive Officer | Disposed G | 3,508 | $0.00 | $0 | 26,835 | Direct |
| 29 May, 2026 | Infrastructure Partners (Uk) Ltd. Atlas | TenPercentOwner | Disposed S | 1,435 | $57.52 | $82.54K | 4,581,034 | Direct |
| 29 May, 2026 | Infrastructure Partners (Uk) Ltd. Atlas | TenPercentOwner | Acquired P | 31,001 | $57.62 | $1.79Mn | 4,612,035 | Direct |
| 13 May, 2026 | Mary Ann Hanley | Director | Acquired A | 1,947 | $0.00 | $0 | 11,583 | Direct |
| 13 May, 2026 | Denise L Kruger | Director | Acquired A | 1,947 | $0.00 | $0 | 6,923 | Direct |
| 13 May, 2026 | Carl Guardino | Director | Acquired A | 1,947 | $0.00 | $0 | 9,139 | Direct |
| 13 May, 2026 | Nick Orlando Rowe | Director | Acquired A | 1,947 | $0.00 | $0 | 2,452 | Direct |
| 13 May, 2026 | Hunt Heather | Director | Acquired A | 1,947 | $0.00 | $0 | 11,238 | Direct |
| 13 May, 2026 | Rebecca A Klein | Director | Acquired A | 1,947 | $0.00 | $0 | 9,208 | Direct |
| 13 May, 2026 | Carol P Wallace | Director | Acquired A | 1,947 | $0.00 | $0 | 11,238 | Direct |
| 13 May, 2026 | Daniel B. More | Director | Acquired A | 1,947 | $0.00 | $0 | 1,947 | Direct |
| 10 Apr, 2026 | Atlas Holdings Ltd Gip | TenPercentOwner | Acquired P | 50,385 | $59.06 | $2.98Mn | 4,582,469 | Direct |
| 10 Apr, 2026 | Infrastructure Partners (Uk) Ltd. Atlas | TenPercentOwner | Acquired P | 50,385 | $59.06 | $2.98Mn | 4,582,469 | Direct |