Eos Energy director buys 15K shares for $58.7K

A director of EOSE made two direct open-market share purchases totaling 15,000 shares in mid-September 2026.

Rhea-AI Filing Summary

Eos Energy Enterprises, Inc. (EOSE) reported that director Haiyan Song purchased a total of 15,000 shares of common stock in two open-market transactions. The purchases occurred on September 11, 2026 (10,000 shares at $3.95 per share) and September 14, 2026 (5,000 shares at $3.84 per share), held directly. No Rule 10b5-1 trading plan is reported and the filing does not state Song’s total holdings after these purchases.

Insider Trade Summary

Net Buyer: 15,000 shares

Net Buy 2 txns

Insider Song Haiyan

Role Director

Bought 15,000 shs ($59K)

Type	Security	Shares	Price	Value
Purchase	Common Stock	5,000	$3.84	$19K
Purchase	Common Stock	10,000	$3.95	$40K

Holdings After Transaction: Common Stock — 15,000 shares (Direct)

Key Figures

Shares purchased September 11, 2026: 10,000 shares Price per share September 11, 2026 purchase: $3.95 per share Shares purchased September 14, 2026: 5,000 shares +3 more

6 metrics

Shares purchased September 11, 2026 10,000 shares Common stock bought directly by director Haiyan Song

Price per share September 11, 2026 purchase $3.95 per share Open-market purchase of 10,000 common shares

Shares purchased September 14, 2026 5,000 shares Common stock bought directly by director Haiyan Song

Price per share September 14, 2026 purchase $3.84 per share Open-market purchase of 5,000 common shares

Total shares purchased 15,000 shares Combined common stock purchases on September 11 and 14, 2026

Approximate aggregate purchase value $58,700 Sum of both reported share purchases at their stated prices

Key Terms

Common Stock, open-market transaction, Rule 10b5-1 trading plan

3 terms

Common Stock financial

"purchased a total of 15,000 shares of common stock in two open-market transactions"

Common stock represents ownership shares in a company, giving investors a stake in its success and a say in important decisions through voting rights. It is the most common type of stock traded on markets and can provide income through dividends, as well as potential for value growth. For investors, holding common stock means sharing in the company’s profits and risks.

open-market transaction financial

"purchased a total of 15,000 shares of common stock in two open-market transactions"

An open-market transaction is a buy or sell of a company's shares or other securities conducted on a public exchange at the current market price, rather than through a private agreement. Investors watch these trades because they change the number of shares available and can move the price immediately—similar to how a large purchase at a busy store can raise demand and affect the checkout price—so such activity can signal market sentiment and alter ownership stakes.

Rule 10b5-1 trading plan regulatory

"No Rule 10b5-1 trading plan is reported for these purchases"

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.

FAQ

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

What insider transactions were reported for EOSE in this Form 4?

The Form 4 reports that director Haiyan Song purchased a total of 15,000 shares of Eos Energy Enterprises, Inc. common stock in two direct, open-market transactions on September 11 and 14, 2026.

How many EOSE shares did the director buy and at what prices?

Haiyan Song bought 10,000 shares at $3.95 per share on September 11, 2026 and 5,000 shares at $3.84 per share on September 14, 2026, for a total of 15,000 shares acquired.

Was a Rule 10b5-1 trading plan involved in this EOSE insider purchase?

No. The Form 4 indicates that these transactions were not made under a Rule 10b5-1 trading plan, meaning they were not reported as pre-scheduled trades under such a plan.

Does the Form 4 state Haiyan Song’s total EOSE holdings after the transactions?

No. The Form 4 reports the shares purchased in each transaction but does not state the total number of EOSE shares beneficially owned by Haiyan Song following these purchases.

What is the approximate total value of the EOSE shares purchased by the director?

Based on the reported per-share prices, the two purchases total approximately $58,700, consisting of $39,500 for 10,000 shares at $3.95 and $19,200 for 5,000 shares at $3.84.

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

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Available on EDGAR 09/15/2026 - 08:57 AM Accepted by SEC EDGAR 09/15/2026 - 08:56 AM Learn about SEC filing dates

SEC Form 4

FORM 4

UNITED STATES SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP

Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934
or Section 30(h) of the Investment Company Act of 1940

OMB APPROVAL

OMB Number:			3235-0287
Estimated average burden
hours per response:			0.5

Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).

Check this box to indicate that a transaction was made pursuant to a contract, instruction or written plan for the purchase or sale of equity securities of the issuer that is intended to satisfy the affirmative defense conditions of Rule 10b5-1(c). See Instruction 10.

1. Name and Address of Reporting Person^*

Song Haiyan

(Last) (First) (Middle)

C/O EOS ENERGY ENTERPRISES, INC.

TWO ALLEGHENY CENTER, NOVA TOWER 2

(Street)

PITTSBURGH PENNSYLVANIA 15212

(City) (State) (Zip)

UNITED STATES

(Country)

2. Issuer Name and Ticker or Trading Symbol
Eos Energy Enterprises, Inc. [ EOSE ]

5. Relationship of Reporting Person(s) to Issuer
(Check all applicable)

X	Director		10% Owner
	Officer (give title below)		Other (specify below)

2a. Foreign Trading Symbol

3. Date of Earliest Transaction (Month/Day/Year)
09/11/2026

6. Individual or Joint/Group Filing (Check Applicable Line)

X	Form filed by One Reporting Person
	Form filed by More than One Reporting Person

4. If Amendment, Date of Original Filed (Month/Day/Year)

Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned
1. Title of Security (Instr. 3)	2. Transaction Date (Month/Day/Year)	2A. Deemed Execution Date, if any (Month/Day/Year)	3. Transaction Code (Instr. 8)		4. Securities Acquired (A) or Disposed Of (D) (Instr. 3, 4 and 5)			5. Amount of Securities Beneficially Owned Following Reported Transaction(s) (Instr. 3 and 4)	6. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	7. Nature of Indirect Beneficial Ownership (Instr. 4)
			Code	V	Amount	(A) or (D)	Price
Common Stock	09/11/2026		P		10,000	A	$3.95	10,000	D
Common Stock	09/14/2026		P		5,000	A	$3.84	15,000	D

Table II - Derivative Securities Acquired, Disposed of, or Beneficially Owned (e.g., puts, calls, warrants, options, convertible securities)
1. Title of Derivative Security (Instr. 3)	2. Conversion or Exercise Price of Derivative Security	3. Transaction Date (Month/Day/Year)	3A. Deemed Execution Date, if any (Month/Day/Year)	4. Transaction Code (Instr. 8)		5. Number of Derivative Securities Acquired (A) or Disposed of (D) (Instr. 3, 4 and 5)		6. Date Exercisable and Expiration Date (Month/Day/Year)		7. Title and Amount of Securities Underlying Derivative Security (Instr. 3 and 4)		8. Price of Derivative Security (Instr. 5)	9. Number of derivative Securities Beneficially Owned Following Reported Transaction(s) (Instr. 4)	10. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	11. Nature of Indirect Beneficial Ownership (Instr. 4)
				Code	V	(A)	(D)	Date Exercisable	Expiration Date	Title	Amount or Number of Shares

Explanation of Responses:

Remarks:

	/s/ Sumeet Puri as attorney-in-fact for Haiyan Song	09/15/2026
	** Signature of Reporting Person	Date
Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.
* If the form is filed by more than one reporting person, see Instruction 4 (b)(v).
** Intentional misstatements or omissions of facts constitute Federal Criminal Violations See 18 U.S.C. 1001 and 15 U.S.C. 78ff(a).
Note: File three copies of this Form, one of which must be manually signed. If space is insufficient, see Instruction 6 for procedure.
Persons who respond to the collection of information contained in this form are not required to respond unless the form displays a currently valid OMB Number.
* Form 4: SEC 1474 (03-26)