Solid Power, Inc. (SLDP) director reports sale of 30,000 shares

Rhea-AI Filing Summary

Solid Power, Inc. director Erik J. Anderson reported selling 30,000 shares of common stock on December 4, 2025 at a price of $5.2024 per share. The transaction was coded as a sale and disclosed on a Form 4 filed for one reporting person.

Following this transaction, he reports beneficial ownership of 157,617 shares held indirectly through WestRiver Management, LLC and 260,370 shares held directly. Anderson is identified as the sole member and sole manager of WestRiver Management, LLC, which explains the indirect ownership reported.

Insider Trade Summary

Net Seller: 30,000 shares

Net Sell 2 txns

Insider ANDERSON ERIK J

Role Director

Sold 30,000 shs ($156K)

Type	Security	Shares	Price	Value
Sale	Common Stock	30,000	$5.2024	$156K
holding	Common Stock	--	--	--

Holdings After Transaction: Common Stock — 157,617 shares (Indirect, By WestRiver Management, LLC); Common Stock — 260,370 shares (Direct)

Footnotes (1)

1. F1. The reporting person is the sole member and sole manager of WestRiver Management, LLC.

FAQ

What insider stock transaction did Solid Power (SLDP) disclose?

The filing shows that director Erik J. Anderson sold 30,000 shares of Solid Power, Inc. common stock on December 4, 2025, coded as a sale.

At what price were the 30,000 Solid Power (SLDP) shares sold?

The 30,000 shares of Solid Power, Inc. common stock were sold at a price of $5.2024 per share.

How many Solid Power (SLDP) shares does Erik J. Anderson own after the transaction?

After the reported sale, Erik J. Anderson reports 157,617 shares owned indirectly through WestRiver Management, LLC and 260,370 shares owned directly.

What is Erik J. Anderson’s relationship to Solid Power, Inc. (SLDP)?

The filing identifies Erik J. Anderson as a director of Solid Power, Inc., with the director box checked in the relationship section.

What is WestRiver Management, LLC’s role in Erik J. Anderson’s SLDP holdings?

The filing explains that Anderson is the sole member and sole manager of WestRiver Management, LLC, through which he indirectly holds 157,617 shares of Solid Power common stock.

Was this Solid Power (SLDP) Form 4 filed by one or multiple reporting persons?

The Form 4 is indicated as being filed by one reporting person, with the corresponding box checked in the filing.

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Form 4 Insider Transactions: What Each Field Means →

Accepted by SEC EDGAR 12/08/2025 - 05:04 PM 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^*

ANDERSON ERIK J

(Last) (First) (Middle)

C/O SOLID POWER, INC.

486 S. PIERCE AVE., SUITE E

(Street)

LOUISVILLE CO 80027

(City) (State) (Zip)

2. Issuer Name and Ticker or Trading Symbol
Solid Power, Inc. [ SLDP ]

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

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

3. Date of Earliest Transaction (Month/Day/Year)
12/04/2025

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

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

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

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	12/04/2025		S		30,000	D	$5.2024	157,617	I	By WestRiver Management, LLC(1)
Common Stock								260,370	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:

1. The reporting person is the sole member and sole manager of WestRiver Management, LLC.

	/s/ Erik J. Anderson	12/08/2025
	** 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.