EOSEEos Energy Enterprises, Inc. · Insider ownership research

Eos Energy Enterprises, Inc. insiders sold $18.0M in the past 12 months. How much of their stake is that?

23% was sold under disclosed trading plans, 3% to cover taxes, 74% with no plan disclosed. The largest seller, Russell Stidolph (Director), sold $11.5M. 23% of these sales were shares from exercising options.Share-of-stake figures for this company are being verified and will be added when that check is finished. Why

Updated Oct 16, 2026 from SEC filings · covers Oct 17, 2025 to Oct 16, 2026

4

buyers among officers and directors (6 trades), past 12 months

23%

of sales were under disclosed trading plans, past 12 months

8 of 17

officers and directors sold shares, past 12 months

Is this normal? More than usual: $18.0M sold, after almost none in the past 5 years. 8 insiders sold; the average is 2 a year. Year by year

Latest filing: Filed Sep 16 for a sale on Sep 16. Joe Mastrangelo sold 250K shares ($980K) to cover taxes on vesting stock. Filing

SEC ownership filings: 74 filed in the 12 months to Oct 16, 2026; 318 on record since May 19, 2020 · See the evidence

What stands out

Two directors sold $12.8M with no disclosed plan: Russell Stidolph ($11.5M) and Marian Walters ($1.3M). The filings don't state a reason.Russell Stidolph: largest such sale, Dec 5, 2025 · Marian Walters: largest such sale, Dec 4, 2025

Four insiders bought shares: Joe Mastrangelo (84K shares, $502K), David Urban (16K shares, $100K) and Alexander Dimitrief (15K shares, $91K), plus 1 more.Joe Mastrangelo: purchase, Mar 2, 2026 · David Urban: purchase, Mar 9, 2026 · Alexander Dimitrief: purchase, Mar 2, 2026

A share of stake is shown for 0 of the 8 officers and directors who sold. 17 are left out

i

Left out: Russell Stidolph, Joe Mastrangelo, Nathan Kroeker, Jeff McNeil, Michael Silberman, Alexander Dimitrief, Sumeet Puri, Jeffrey Bornstein, Claude Demby, Marian Walters, Michelle Buczkowski, David Urban, Joseph Nigro, Alessandro Lagi, Gregory Nixon, Marie Martin and Haiyan Song (share of stake is being verified).

Disclosed company stock is not an insider's whole wealth.

Who sold, and how much of their stake

Officers and directors, past 12 months. Their share of stake is being verified and is not shown yet; amounts and trading plans are below.

Russell Stidolph

Director

Not confirmed

Share of stake not shown: share of stake is being verified. Why

$11.5MNo plan disclosed

Nathan Kroeker

Chief Commercial Officer

Not confirmed

Share of stake not shown: share of stake is being verified. Why

$1.8MDisclosed plan

Joe Mastrangelo

Chief Executive Officer, Director

Not confirmed

Share of stake not shown: share of stake is being verified. Why

$1.6M63% planned, 37% to cover taxes

Marian Walters

Director

Not confirmed

Share of stake not shown: share of stake is being verified. Why

$1.3MNo plan disclosed

Michael Silberman

Chief Legal Officer

Not confirmed

Share of stake not shown: share of stake is being verified. Why

$827KDisclosed plan

Selling by month

Officers and directors, Oct 2025 to Oct 2026. Each sale is counted once: under a disclosed plan, else to cover taxes, else no plan disclosed.

Disclosed planTo cover taxesNo plan disclosedOne dollar scale for every month; the tallest bar is labeled

Recent activity

Past 30 days, Sep 17, 2026 to Oct 16, 2026

No officer or director trades were reported for the past 30 days. The most recent before that:

Sep 16, 20262 executives sold 294K shares ($1.2M) to cover taxes on vesting stock.

Who	Shares	Price	% of total stake	Total stake after	Trade date	Filed
Joe Mastrangelo Chief Executive Officer, Director Also under a disclosed plan	250,000	$3.92	n/a	n/a	Sep 16, 2026	Sep 16, 2026
Sumeet Puri Chief Accounting Officer Also under a disclosed plan	43,750	$3.92	n/a	n/a	Sep 16, 2026	Sep 16, 2026

Outside holders, reported separately

Cerberus GP Manager LLC reported no open-market sales in the past 12 months. Large shareholders and the funds or companies that board members represent are not part of management, so they are left out of the figures above.

Common questions

Is the Eos Energy Enterprises, Inc. CEO selling stock?

Yes. Joe Mastrangelo sold 409K shares ($1.6M) in the past 12 months, 63% of it under a trading plan disclosed in the filings.

Why are Eos Energy Enterprises, Inc. insiders selling?

Filings rarely give a reason, and we don't guess at one. What they show is how the sales were made: 23% of sales by value ran under 10b5-1 trading plans disclosed in the filings, 3% were to cover taxes and 74% had no disclosed plan. A trading plan schedules sales in advance.

Are any Eos Energy Enterprises, Inc. insiders buying?

Yes. 4 officers or directors reported 6 purchases in the past 12 months (Form 4 code P; rows the filings describe as reinvested dividends, plan purchases, private deals or moves into the person's own trust are not counted).

The evidence

Who sold8 officers and directors: amount, % of holdings, trading plan

Who sold	Amount	% of holdings	Trading plan
Russell Stidolph Director	$11.5M 766K shares	Not confirmed share of stake is being verified. Why	No plan disclosed
Nathan Kroeker Chief Commercial Officer	$1.8M 275K shares	Not confirmed share of stake is being verified. Why	Disclosed plan
Joe Mastrangelo Chief Executive Officer, Director	$1.6M 409K shares	Not confirmed share of stake is being verified. Why	63% under a disclosed plan, 37% to cover taxes
Marian Walters Director	$1.3M 110K shares	Not confirmed share of stake is being verified. Why	No plan disclosed
Michael Silberman Chief Legal Officer	$827K 57K shares	Not confirmed share of stake is being verified. Why	Disclosed plan
Jeffrey Bornstein Director	$613K 40K shares	Not confirmed share of stake is being verified. Why	No plan disclosed
Sumeet Puri Chief Accounting Officer	$462K 116K shares	Not confirmed share of stake is being verified. Why	Disclosed plan
Michelle Buczkowski Chief Commercial Officer	$67K 11K shares	Not confirmed share of stake is being verified. Why	Disclosed plan

Outside holder, reported separately: Cerberus GP Manager LLC (a 10% owner, not part of management). No open-market sales reported in the period. Latest filing

The full ownership picture0 of 17 officers and directors confirmed

Vested shares across all share classes, held directly and through trusts, LLCs and family members, as reported on SEC Forms 3, 4 and 5. Unvested awards and options are never counted as owned shares.

Insider

Held Oct 16, 2025

Sold

Held Oct 16, 2026

Still held

Russell Stidolph

!

Holdings and share of stake are being verified. Share-of-stake figures and holdings for this company are held back while they are verified. Sales and other transactions for Russell Stidolph are complete.

Director

n/a

−766K

n/a

n/a

Vesting, gifts, unvested awards and holding lines for Russell Stidolph

Holdings and share of stake are being verified. Sales, proceeds, plan and tax status and dates for Russell Stidolph are complete; balances and unit counts will be added when the check is finished.

−75Kgifted (net of own trusts)

−60Kwithheld by the company for taxes

Joe Mastrangelo

!

Holdings and share of stake are being verified. Share-of-stake figures and holdings for this company are held back while they are verified. Sales and other transactions for Joe Mastrangelo are complete.

Chief Executive Officer, Director

n/a

−409K

n/a

n/a

Vesting, gifts, unvested awards and holding lines for Joe Mastrangelo

Holdings and share of stake are being verified. Sales, proceeds, plan and tax status and dates for Joe Mastrangelo are complete; balances and unit counts will be added when the check is finished.

0gifted (net of own trusts)

−299Kwithheld by the company for taxes

Nathan Kroeker

!

Holdings and share of stake are being verified. Share-of-stake figures and holdings for this company are held back while they are verified. See the filing Sales and other transactions for Nathan Kroeker are complete.

Chief Commercial Officer

n/a

−275K

n/a

n/a

Vesting, gifts, unvested awards and holding lines for Nathan Kroeker

Holdings and share of stake are being verified. Sales, proceeds, plan and tax status and dates for Nathan Kroeker are complete; balances and unit counts will be added when the check is finished.

0gifted (net of own trusts)

Jeff McNeil

!

Holdings and share of stake are being verified. Share-of-stake figures and holdings for this company are held back while they are verified. Sales and other transactions for Jeff McNeil are complete.

Director

n/a

0

n/a

n/a

Vesting, gifts, unvested awards and holding lines for Jeff McNeil

Holdings and share of stake are being verified. Sales, proceeds, plan and tax status and dates for Jeff McNeil are complete; balances and unit counts will be added when the check is finished.

−16Kgifted (net of own trusts)

Michael Silberman

!

Holdings and share of stake are being verified. Share-of-stake figures and holdings for this company are held back while they are verified. Sales and other transactions for Michael Silberman are complete.

Chief Legal Officer

n/a

−57K

n/a

n/a

Vesting, gifts, unvested awards and holding lines for Michael Silberman

Holdings and share of stake are being verified. Sales, proceeds, plan and tax status and dates for Michael Silberman are complete; balances and unit counts will be added when the check is finished.

0gifted (net of own trusts)

Alexander Dimitrief

!

Holdings and share of stake are being verified. Share-of-stake figures and holdings for this company are held back while they are verified. Sales and other transactions for Alexander Dimitrief are complete.

Director

n/a

0

n/a

n/a

Vesting, gifts, unvested awards and holding lines for Alexander Dimitrief

Holdings and share of stake are being verified. Sales, proceeds, plan and tax status and dates for Alexander Dimitrief are complete; balances and unit counts will be added when the check is finished.

0gifted (net of own trusts)

−18Kwithheld by the company for taxes

Sumeet Puri

!

Holdings and share of stake are being verified. Share-of-stake figures and holdings for this company are held back while they are verified. Sales and other transactions for Sumeet Puri are complete.

Chief Accounting Officer

n/a

−116K

n/a

n/a

Vesting, gifts, unvested awards and holding lines for Sumeet Puri

Holdings and share of stake are being verified. Sales, proceeds, plan and tax status and dates for Sumeet Puri are complete; balances and unit counts will be added when the check is finished.

0gifted (net of own trusts)

Jeffrey Bornstein

!

Holdings and share of stake are being verified. Share-of-stake figures and holdings for this company are held back while they are verified. Sales and other transactions for Jeffrey Bornstein are complete.

Director

n/a

−40K

n/a

n/a

Vesting, gifts, unvested awards and holding lines for Jeffrey Bornstein

Holdings and share of stake are being verified. Sales, proceeds, plan and tax status and dates for Jeffrey Bornstein are complete; balances and unit counts will be added when the check is finished.

0gifted (net of own trusts)

Claude Demby

!

Holdings and share of stake are being verified. Share-of-stake figures and holdings for this company are held back while they are verified. Sales and other transactions for Claude Demby are complete.

Director

n/a

0

n/a

n/a

Vesting, gifts, unvested awards and holding lines for Claude Demby

Holdings and share of stake are being verified. Sales, proceeds, plan and tax status and dates for Claude Demby are complete; balances and unit counts will be added when the check is finished.

0gifted (net of own trusts)

Marian Walters

!

Holdings and share of stake are being verified. Share-of-stake figures and holdings for this company are held back while they are verified. Sales and other transactions for Marian Walters are complete.

Director

n/a

−110K

n/a

n/a

Vesting, gifts, unvested awards and holding lines for Marian Walters

Holdings and share of stake are being verified. Sales, proceeds, plan and tax status and dates for Marian Walters are complete; balances and unit counts will be added when the check is finished.

0gifted (net of own trusts)

−17Kwithheld by the company for taxes

Stock options (not counted as shares):

Options held	Strike price	Expires	Intrinsic value (estimate)
35,018	$1.18	May 19, 2027	$96K

Estimate: options held × ($3.92 − strike price), using the most recent insider trade price on Form 4 (Sep 16, 2026), not a market close.

Michelle Buczkowski

!

Holdings and share of stake are being verified. Share-of-stake figures and holdings for this company are held back while they are verified. Sales and other transactions for Michelle Buczkowski are complete.

Chief Commercial Officer

n/a

−11K

n/a

n/a

Vesting, gifts, unvested awards and holding lines for Michelle Buczkowski

Holdings and share of stake are being verified. Sales, proceeds, plan and tax status and dates for Michelle Buczkowski are complete; balances and unit counts will be added when the check is finished.

0gifted (net of own trusts)

David Urban

!

Holdings and share of stake are being verified. Share-of-stake figures and holdings for this company are held back while they are verified. Sales and other transactions for David Urban are complete.

Director

n/a

0

n/a

n/a

Vesting, gifts, unvested awards and holding lines for David Urban

Holdings and share of stake are being verified. Sales, proceeds, plan and tax status and dates for David Urban are complete; balances and unit counts will be added when the check is finished.

0gifted (net of own trusts)

Joseph Nigro

!

Holdings and share of stake are being verified. Share-of-stake figures and holdings for this company are held back while they are verified. Sales and other transactions for Joseph Nigro are complete.

Director

n/a

0

n/a

n/a

Vesting, gifts, unvested awards and holding lines for Joseph Nigro

Holdings and share of stake are being verified. Sales, proceeds, plan and tax status and dates for Joseph Nigro are complete; balances and unit counts will be added when the check is finished.

0gifted (net of own trusts)

Alessandro Lagi

!

Holdings and share of stake are being verified. Share-of-stake figures and holdings for this company are held back while they are verified. Sales and other transactions for Alessandro Lagi are complete.

Chief Financial Officer

n/a

0

n/a

n/a

Vesting, gifts, unvested awards and holding lines for Alessandro Lagi

Holdings and share of stake are being verified. Sales, proceeds, plan and tax status and dates for Alessandro Lagi are complete; balances and unit counts will be added when the check is finished.

0gifted (net of own trusts)

Gregory Nixon

!

Holdings and share of stake are being verified. Share-of-stake figures and holdings for this company are held back while they are verified. Sales and other transactions for Gregory Nixon are complete.

Director

n/a

0

n/a

n/a

Vesting, gifts, unvested awards and holding lines for Gregory Nixon

Holdings and share of stake are being verified. Sales, proceeds, plan and tax status and dates for Gregory Nixon are complete; balances and unit counts will be added when the check is finished.

0gifted (net of own trusts)

Marie Martin

!

Holdings and share of stake are being verified. Share-of-stake figures and holdings for this company are held back while they are verified. Sales and other transactions for Marie Martin are complete.

Chief Legal Officer

n/a

0

n/a

n/a

Vesting, gifts, unvested awards and holding lines for Marie Martin

Holdings and share of stake are being verified. Sales, proceeds, plan and tax status and dates for Marie Martin are complete; balances and unit counts will be added when the check is finished.

0gifted (net of own trusts)

Haiyan Song

!

Holdings and share of stake are being verified. Share-of-stake figures and holdings for this company are held back while they are verified. Sales and other transactions for Haiyan Song are complete.

Director

n/a

0

n/a

n/a

Vesting, gifts, unvested awards and holding lines for Haiyan Song

Holdings and share of stake are being verified. Sales, proceeds, plan and tax status and dates for Haiyan Song are complete; balances and unit counts will be added when the check is finished.

0gifted (net of own trusts)

Holdings and share of stake for Eos Energy Enterprises, Inc. are being verified, so no balances, unit counts or percentages are shown. Sales, proceeds, plan and tax status, titles and dates come straight from individual filings.

What explains the selling$18.0M of sales by plan status, purpose, seller and month

Officer and director open-market sales: $18.0M across 1,784,672 shares. Plan status and stated purpose are separate questions, and a sale can have both.

By plan status

Disclosed plan · $4.1M · 23%

77%

The lighter segment is sales with no plan disclosed in the filing ($13.9M), including tax-related sales outside a plan.

No plan disclosed · $13.4M

Sales with no 10b5-1 plan and no tax reference in the filing. $11.5M of it is Russell Stidolph. No plan disclosed is a statement about the filing, not about why the sale happened. Largest such sale: Russell Stidolph, Dec 5, 2025

Taxes

$4.7M of sales (25.9%) cite tax obligations in their footnotes, $4.1M of them also under a plan. Separately, 393,535 shares ($3.1M) were withheld by the company for taxes, which isn't a market sale. Example: Sumeet Puri, Sep 16, 2026

Purchases · 4 buyers (6 trades)

4 officers and directors bought shares in this period, in 6 trades(Form 4 code P, leaving out rows the filings describe as reinvested dividends, plan purchases, private deals or moves into the person's own trust). Across all their filings on record there are 25 purchase trades.

Charitable gifts · 91K shares

Gifts the filings describe as charitable. Gifts are not sales and are not included in the sale totals.

Seller	Shares sold	Proceeds	Under a disclosed plan	Share of total	Sales dates
Russell Stidolph Director	766K	$11.5M	0%	64%	Dec 5, 2025 to Dec 8, 2025
Nathan Kroeker Chief Commercial Officer	275K	$1.8M	100%	10%	Jan 26, 2026 to Jul 28, 2026
Joe Mastrangelo Chief Executive Officer, Director	409K	$1.6M	63%	9%	Jul 27, 2026 to Sep 16, 2026
Marian Walters Director	110K	$1.3M	0%	7%	Dec 4, 2025 to May 28, 2026
Michael Silberman Chief Legal Officer	57K	$827K	100%	5%	Jan 23, 2026 to Jun 30, 2026
Jeffrey Bornstein Director	40K	$613K	0%	3%	Dec 4, 2025 to Dec 5, 2025
Sumeet Puri Chief Accounting Officer	116K	$462K	100%	3%	Jun 30, 2026 to Sep 16, 2026
Michelle Buczkowski Chief Commercial Officer	11K	$67K	100%	0.4%	Jun 30, 2026 to Jun 30, 2026

Sales by month

Month	Sale proceeds	Disclosed plan	To cover taxes	No plan disclosed
Oct 2025	$0	$0	$0	$0
Nov 2025	$0	$0	$0	$0
Dec 2025	$12.9M	$0	$0	$12.9M
Jan 2026	$1.5M	$1.5M	$0	$0
Feb 2026	$0	$0	$0	$0
Mar 2026	$0	$0	$0	$0
Apr 2026	$0	$0	$0	$0
May 2026	$490K	$0	$0	$490K
Jun 2026	$414K	$414K	$0	$0
Jul 2026	$1.4M	$840K	$575K	$0
Aug 2026	$0	$0	$0	$0
Sep 2026	$1.3M	$1.3M	$0	$0
Oct 2026	$0	$0	$0	$0

Is this normal? Selling year by year5 earlier years to compare with

More than usual: $18.0M sold, after almost none in the past 5 years. 8 insiders sold; the average is 2 a year.

12 months ending	Shares sold	Insiders who sold	Proceeds
Oct 16, 2026 Latest 12 months	1.78M	8	$18.0M
Oct 16, 2025 1 year earlier	1.24M	6	$7.9M
Oct 16, 2024 2 years earlier	163K	1	$428K
Oct 17, 2023 3 years earlier	1.01M	2	$1.3M
Oct 17, 2022 4 years earlier	0	0	$0
Oct 17, 2021 5 years earlier	0	0	$0

Open-market sales (Form 4 code S) by people who were officers or directors, in split-adjusted shares. Earlier years include people who have since left. A sale that an outside holder also reports (a family trust, a fund) is counted with outside holders in every year. Shares, not dollars, are compared, so a change in the stock price doesn't look like a change in selling. Years the filings don't fully cover are shown but left out of the average.

Known gaps and uncertainty17 officers and directors not confirmed

Holdings and share of stake are being verified. Balances, unit counts and every share-of-stake figure for Eos Energy Enterprises, Inc. are held back until that check is finished. Sales, proceeds, plan and tax status, titles and dates come straight from individual filings and are complete.

External context: we only cite outside events when a documented connection exists. None is shown for this period.

Sources and methodology318 filings on record, 74 filed in the 12-month period, and how we read them

All 318 Forms 3, 4 and 5 on record for Eos Energy Enterprises, Inc. (SEC CIK 1805077), filed from May 19, 2020 to Sep 16, 2026; 74 of them were filed in the 12 months this page covers, retrieved from SEC EDGAR on Oct 16, 2026. Prices are the ones reported in each filing, often weighted averages.

Holdings. Each holding line (a share class plus an owner, such as a trust or LLC) carries its last reported balance forward. Entities first reported during the period start at zero, so transfers between an insider's own trusts don't count as selling. Lines not reported for three years or more are listed separately and left out of totals.

Sales. A sale counts as under a 10b5-1 plan if its footnote cites one or the filing's Rule 10b5-1 box is checked, and as tax-related if its footnote cites tax obligations or sell-to-cover. Shares withheld by the company for taxes are listed separately. Sales with neither attribute are labeled "no plan disclosed".

Full methodology

Former or inactive filers (22)No filing in 18 months; last reported balances, not in any total

Name	Last filed	Last reported balance
Eric Javidi	Mar 19, 2025	No balance on record
Cerberus Capital Management II, L.P.	Jan 27, 2025	No balance on record
Audrey Zibelman	May 2, 2024	104,897 shares, last reported balance as of Apr 30, 2024
Melissa Berube	Jan 30, 2024	171,836 shares, last reported balance as of Jan 27, 2024
John Tedone	Feb 16, 2023	25,487 shares, last reported balance as of Feb 14, 2023
Randall Gonzales	Jan 13, 2023	188,094 shares, last reported balance as of Jan 11, 2023
Wood River Capital, LLC	Jan 4, 2023	2,538,261 shares, last reported balance as of Dec 30, 2022
Daniel Shribman	Nov 10, 2022	33,960 shares, last reported balance as of Nov 10, 2022
B. Riley Financial, Inc.	Aug 1, 2022	9,242,797 shares, last reported balance as of Aug 1, 2022
Krishna Singh	Mar 30, 2022	2,794,709 shares, last reported balance as of Apr 9, 2021
Sagar Kurada	Jan 5, 2022	66,939 shares, last reported balance as of Jan 3, 2022
Markopoulos Jody	Mar 31, 2021	No balance on record
Mack Treece	Feb 16, 2021	No balance on record
Balakrishnan Iyer	Nov 25, 2020	No balance on record
Patrick Bartels Jr.	May 19, 2020	20,000 shares, last reported balance as of May 19, 2020
James Kempner	May 19, 2020	20,000 shares, last reported balance as of May 19, 2020
Timothy Presutti	May 19, 2020	20,000 shares, last reported balance as of May 19, 2020
Robert Suss	May 19, 2020	20,000 shares, last reported balance as of May 19, 2020
Kenneth Young		No balance on record
Fabian Strauss		No balance on record
Nicholas Robinson		No balance on record
Nathaniel Fick		No balance on record

Spotted something wrong on this page? Report an error. We check every report against the SEC filing and list what we fix in the corrections log.