Eos Energy holder plans 250K-share Rule 144 sale

Rhea-AI Filing Summary

Eos Energy Enterprises, Inc. (EOSE) disclosed that Joseph Mastrangelo plans to sell up to 250,000 shares of common stock under Rule 144 through UBS Financial Services Inc. The planned sale, valued at approximately $1,037,500, is pursuant to a Rule 10b5-1 trading plan adopted to cover estimated tax withholding obligations from the vesting of restricted stock units on September 14, 2026.

Key Figures

Shares to be sold: 250,000 shares Aggregate market value: $1,037,500 Shares outstanding: 364,167,744 shares +2 more

5 metrics

Shares to be sold 250,000 shares Planned Rule 144 sale related to RSU vesting on September 14, 2026

Aggregate market value $1,037,500 Approximate value of 250,000 shares of Eos Energy Enterprises, Inc. common stock

Shares outstanding 364,167,744 shares Common shares outstanding of Eos Energy Enterprises, Inc. at the time referenced

Date of RSU vesting September 14, 2026 Date on which restricted stock units vested, prompting the planned sale

Date of notice September 16, 2026 Date the Rule 144 notice was signed/submitted

Key Terms

Rule 144, Rule 10b5-1 trading plan, restricted stock units, estimated tax withholding obligations

4 terms

Rule 144 regulatory

"See the definition of "person" in paragraph (a) of Rule 144."

Rule 144 is a U.S. securities regulation that sets conditions under which restricted or insider-held shares can be legally resold to the public, such as required holding periods, availability of public information, limits on how much can be sold at once, and certain filing requirements. For investors it matters because it determines when previously locked-up shares can enter the market — like a release valve that can increase supply, affect share price, and signal insider intent.

Rule 10b5-1 trading plan regulatory

"will be sold pursuant to a Rule 10b5-1 trading plan adopted by the reporting person"

A Rule 10b5-1 trading plan is a pre-arranged schedule that allows company insiders to buy or sell stock at specific times, even if they have inside information. It helps prevent accusations of unfair trading by making these transactions look planned and transparent, rather than sneaky or illegal.

restricted stock units financial

"from the vesting of restricted stock units."

Restricted stock units are a type of company reward where employees are promised shares of stock, but they only fully own these shares after meeting certain conditions, like staying with the company for a set time. They matter because they can become valuable assets and are often used to motivate employees to help the company succeed.

estimated tax withholding obligations financial

"to cover estimated tax withholding obligations from the vesting of restricted stock units."

FAQ

AI-generated questions and answers. How Rhea-AI works. Not financial advice.

What does the Form 144 filing disclose for EOSE?

The filing reports that 250,000 shares of Eos Energy Enterprises, Inc. common stock may be sold under Rule 144 by or for the account of Joseph Mastrangelo through UBS Financial Services Inc.

How many EOSE shares are covered by Joseph Mastrangelo’s planned sale?

The notice covers a planned sale of 250,000 shares of Eos Energy Enterprises, Inc. common stock, related to the vesting of restricted stock units on September 14, 2026.

What is the approximate value of the EOSE shares in this Form 144?

The Form 144 lists an approximate aggregate market value of $1,037,500 for the 250,000 shares of Eos Energy Enterprises, Inc. common stock covered by the notice.

Why are the EOSE shares being sold according to the Form 144?

The filing states the shares will be sold pursuant to a Rule 10b5-1 trading plan adopted by the reporting person to cover estimated tax withholding obligations from the vesting of restricted stock units.

Who is the broker involved in the planned sale of EOSE shares?

The Form 144 identifies UBS Financial Services Inc. as the broker handling the 250,000-share planned sale of Eos Energy Enterprises, Inc. common stock.

On which market are the EOSE shares listed in this Form 144?

The Form 144 specifies that the common stock of Eos Energy Enterprises, Inc. involved in the planned sale is listed on the NASDAQ market.

AI-generated analysis. How Rhea-AI works. Not financial advice.

See more from StockTitan in Google Search and AI answers. Adds StockTitan as a preferred source · opens Google

Add on Google Not now

Available on EDGAR 09/16/2026 - 04:08 PM Accepted by SEC EDGAR 09/16/2026 - 04:07 PM Learn about SEC filing dates

Form 144 Filer Information	UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 Form 144 NOTICE OF PROPOSED SALE OF SECURITIES PURSUANT TO RULE 144 UNDER THE SECURITIES ACT OF 1933
FORM 144

144: Filer Information

Filer CIK	0001833309
Filer CCC	XXXXXXXX
Is this a LIVE or TEST Filing?	LIVE TEST
Submission Contact Information
Name
Phone
E-Mail Address

144: Issuer Information

Name of Issuer	Eos Energy Enterprises, Inc.
SEC File Number	001-39291
Address of Issuer	TWO ALLEGHENY CENTER NOVA TOWER 2 PITTSBURGH PENNSYLVANIA 15212
Phone	(732) 225-8400
Name of Person for Whose Account the Securities are To Be Sold	Mastrangelo Joe
See the definition of "person" in paragraph (a) of Rule 144. Information is to be given not only as to the person for whose account the securities are to be sold but also as to all other persons included in that definition. In addition, information shall be given as to sales by all persons whose sales are required by paragraph (e) of Rule 144 to be aggregated with sales for the account of the person filing this notice.
Relationship to Issuer	Officer
Relationship to Issuer	Director

144: Securities Information

Title of the Class of Securities To Be Sold	Name and Address of the Broker	Number of Shares or Other Units To Be Sold	Aggregate Market Value	Number of Shares or Other Units Outstanding	Approximate Date of Sale	Name the Securities Exchange
Common	UBS Financial Services, Inc. 11 Madison Ave 4th Floor New York NY 10010	250000	1037500.00	364167744	09/16/2026	NASDAQ

Furnish the following information with respect to the acquisition of the securities to be sold and with respect to the payment of all or any part of the purchase price or other consideration therefor:

144: Securities To Be Sold

Title of the Class	Date you Acquired	Nature of Acquisition Transaction	Name of Person from Whom Acquired	Is this a Gift?	Date Donor Acquired	Amount of Securities Acquired	Date of Payment	Nature of Payment *
Common	09/14/2026	RSU Vesting	Issuer			250000	09/14/2026	N/A

* If the securities were purchased and full payment therefor was not made in cash at the time of purchase, explain in the table or in a note thereto the nature of the consideration given. If the consideration consisted of any note or other obligation, or if payment was made in installments describe the arrangement and state when the note or other obligation was discharged in full or the last installment paid.

Furnish the following information as to all securities of the issuer sold during the past 3 months by the person for whose account the securities are to be sold.

144: Securities Sold During The Past 3 Months

Nothing to Report

144: Remarks and Signature

Remarks	The shares reported on this Form 144 will be sold pursuant to a Rule 10b5-1 trading plan adopted by the reporting person to cover estimated tax withholding obligations from the vesting of restricted stock units.
Date of Notice	09/16/2026
Date of Plan Adoption or Giving of Instruction, If Relying on Rule 10b5-1	06/15/2026
ATTENTION:
The person for whose account the securities to which this notice relates are to be sold hereby represents by signing this notice that he does not know any material adverse information in regard to the current and prospective operations of the Issuer of the securities to be sold which has not been publicly disclosed. If such person has adopted a written trading plan or given trading instructions to satisfy Rule 10b5-1 under the Exchange Act, by signing the form and indicating the date that the plan was adopted or the instruction given, that person makes such representation as of the plan adoption or instruction date.
Signature	/s/ UBS Financial Services Inc, as attorney-in-fact for Joseph Mastrangelo
ATTENTION: Intentional misstatements or omission of facts constitute Federal Criminal Violations (See 18 U.S.C. 1001)