Energy Recovery ERII Insider Ownership

NASDAQ ERII

$6.64 -0.02 (-0.30%)

At close: Oct 20, 2026 · 4:00 PM EDT

Insider Holdings by Owner

1.73Mn Shares

Insider Ownership Statistics

as of 30 Sep, 2026

Insider Ownership

2.93%

▲+0.0082% pp QoQ

Shares Held by Insiders

1.51Mn

filed for Sep 2026

▲+0.28% QoQ

Shares Outstanding

51.46Mn

51,463,000 shares

Direct Holdings

1.35Mn

Indirect: 154.61K

Net Shares Traded (QoQ)

+4.21K

net buying in Sep 2026

Insiders Holding Shares

with Form 4 holdings on file

Shares Owned by Insiders

Shares held % of outstanding

Latest —

Average ownership —

Peak ownership —

Shares Purchased/Sold by Insiders

Bought Sold

Latest quarter —

Net over range —

Buying quarters —

Insider Ownership Summary

Updated Oct 10, 2026

In the last 12 months, insiders at Energy Recovery made open-market purchases of $266,107 (31.18K shares) and open-market sales of $3.86 million (345.9K shares).

Counted by insider, open-market buying of ERII stock in the past 12 months came from 2 insiders and selling from 5 insiders.
Among ERII insiders, Pamela L. Tondreau (Director) bought the most stock on the open market in the past 12 months: $166,840 (20K shares), most recently on May 13, 2026.
On the sell side, Arve Hanstveit (Director) led open-market sales of Energy Recovery stock over the past 12 months with $2.95 million (272.71K shares), most recently on April 6, 2026.
The latest open-market trade on record is a sale of 5.39K shares for $46,113 by Rodney Clemente (SVP, Water) on July 28, 2026.
Apart from open-market trades, ERII insiders received 258.23K shares in stock awards, acquired 35.09K shares through option exercises and conversions and gave up 51.91K shares to cover taxes or exercise prices in the past 12 months.
According to Business Quant data, insiders at Energy Recovery reported 1.51Mn shares in total in their latest Form 4 filings, up 0.28% from 1.51Mn shares at the end of Q2 2026 and down 17.11% from 1.82Mn shares at the end of Q3 2025.
Indirect holdings, through trusts, partnerships, family members and other entities, make up 10.24% (154.61K shares) of Energy Recovery's insider total, with the other 89.76% (1.35Mn shares) held directly.
The insider holdings in Energy Recovery belong to 14 insiders who have reported on Form 4 within the past two years.
Energy Recovery's three largest insider shareholders, based on their latest Form 4 filings, are Arve Hanstveit (Director, 400.6K shares), David W. Moon (President and CEO, 270.02K shares) and Farshad Ghasripoor (Chief Technology Officer, 123.09K shares).
Of the shares held by ERII insiders, 26.54% belong to Arve Hanstveit.
Institutions held 85.02% of Energy Recovery's outstanding shares in their Q2 2026 13F filings, insiders about 2.93% based on their latest Form 4 filings, and other investors, including the public, the remaining 12.05%.
A total of 35 Form 4 filings with transactions in Energy Recovery stock were made over the past 12 months, by 13 insiders.
These insider figures for Energy Recovery are based on Form 4 filings through July 29, 2026.

Form 4 Holdings

Insiders Holding ERII

Insiders 18

Shares held 1.73Mn

Of outstanding 3.36%

#	Insider	Position	Direct	Indirect	Total	Share of Insiders	Last Filed
1	Arve Hanstveit	Director	400,603	0	400,603	23.2%	05 Jun, 2026
2	Robert Yu Lang Mao	President And Ceo	248,935	0	248,935	14.4%	24 May, 2024
3	David W Moon	President And Ceo	233,069	0	233,069	13.5%	19 Feb, 2026
4	Farshad Ghasripoor	Chief Technology Officer	52,860	70,230	123,090	7.1%	05 Feb, 2025
5	Rodney Clemente	Svp, Water	108,301	0	108,301	6.3%	29 Jul, 2026
6	William Yeung	Chief Legal Officer	99,291	0	99,291	5.7%	29 Jul, 2026
7	Michael S. Mancini	Chief Financial Officer	75,051	0	75,051	4.3%	19 Feb, 2026
8	Alexander J Buehler	Interim President And Ceo	66,755	0	66,755	3.9%	17 Jun, 2026
9	Pamela L. Tondreau	Director	60,844	0	60,844	3.5%	05 Jun, 2026
10	Colin R Sabol	Director	55,671	0	55,671	3.2%	17 Jun, 2026
11	Natarajan Ramanan	Chief Technology Officer	52,565	0	52,565	3.0%	06 Mar, 2026
12	Joan Kai Chow	Director	52,116	0	52,116	3.0%	05 Jun, 2026
13	Matthew Hostetler	Chief Human Resources Officer	46,556	0	46,556	2.7%	19 Feb, 2026
14	Joshua Ballard	Chief Financial Officer	40,376	0	40,376	2.3%	30 May, 2024
15	Aidan Ryan	Interim Cfo	34,133	0	34,133	2.0%	24 Jun, 2026
16	John Joseph Mitchell	Director	16,797	0	16,797	1.0%	21 Jul, 2026
17	Sherif Foda	Director	9,619	0	9,619	0.6%	16 Sep, 2022
18	Lisa A Pollina	Director	4,007	0	4,007	0.2%	13 Jun, 2023

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.

Form 4 Filings

1,375 Insider Transactions

Source SEC Form 4

Latest quarter Sep 2026

Date	Insider	Position	Transaction	Shares	Price	Value	Shares Held After	Ownership
27 Jul, 2026	Rodney Clemente	Svp, Water	Disposed F	2,320	$8.42	$19.53K	113,688	Direct
27 Jul, 2026	William Yeung	Chief Legal Officer	Disposed F	2,828	$8.42	$23.81K	101,339	Direct
28 Jul, 2026	Rodney Clemente	Svp, Water	Disposed S	5,387	$8.56	$46.11K	108,301	Direct
28 Jul, 2026	William Yeung	Chief Legal Officer	Disposed S	2,048	$8.56	$17.53K	99,291	Direct
09 Jul, 2026	John Joseph Mitchell	Director	Acquired A	16,797	$0.00	$0	16,797	Direct
06 May, 2026	Aidan Ryan	Interim Cfo	Acquired A	18,518	$11.61	$214.99K	34,133	Direct
15 Jun, 2026	Alexander J Buehler	Interim President And Ceo	Acquired M	15,327	$8.60	$131.81K	81,655	Direct
15 Jun, 2026	Colin R Sabol	Director	Acquired P	11,180	$8.88	$99.27K	55,671	Direct
15 Jun, 2026	Alexander J Buehler	Interim President And Ceo	Disposed S	14,900	$8.71	$129.78K	66,755	Direct
15 Jun, 2026	Alexander J Buehler	Interim President And Ceo	Disposed M	15,327	$8.60	$131.81K	0	Direct
04 Jun, 2026	Joan Kai Chow	Director	Acquired A	18,094	$8.29	$150.00K	52,116	Direct
04 Jun, 2026	Pamela L. Tondreau	Director	Acquired A	22,316	$8.29	$185.00K	60,844	Direct
04 Jun, 2026	Colin R Sabol	Director	Acquired A	18,094	$8.29	$150.00K	44,491	Direct
04 Jun, 2026	Arve Hanstveit	Director	Acquired A	18,094	$8.29	$150.00K	400,603	Direct
13 May, 2026	Pamela L. Tondreau	Director	Acquired P	20,000	$8.34	$166.84K	37,362	Indirect
06 Apr, 2026	Arve Hanstveit	Director	Disposed S	2,419	$10.29	$24.89K	382,509	Direct
02 Apr, 2026	Arve Hanstveit	Director	Disposed S	165,292	$10.14	$1.68Mn	384,928	Direct
10 Mar, 2026	Arve Hanstveit	Director	Disposed S	25,000	$10.96	$273.98K	550,220	Direct
05 Mar, 2026	Arve Hanstveit	Director	Disposed S	38,418	$10.71	$411.46K	586,802	Direct
06 Mar, 2026	Arve Hanstveit	Director	Disposed S	11,582	$10.62	$122.94K	575,220	Direct

Showing 1 to 20 of 1,375 transactions