Avalanche Treasury CFO acquires 299K-unit stock grant

Q: How many AVAT shares were withheld for Sean William Ostrower’s RSU taxes?

The issuer withheld 15,541 Class A common shares on September 30, 2026, to satisfy tax withholding upon RSU vesting. The reported price was $1.90 per share.

One-eighth of the RSUs vests on each of the first eight six-month anniversaries of March 9, 2026.

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Form Type

Rhea-AI Filing Summary

Avalanche Treasury Corp (AVAT) Chief Financial Officer Sean William Ostrower acquired 299,401 restricted stock units on September 28, 2026. Each RSU represents a contingent right to receive one Class A common share. On September 30, 2026, 15,541 Class A common shares were withheld by the issuer to satisfy tax withholding upon RSU vesting, at a reported price of $1.90 per share.

Insider Trade Summary

2 transactions reported

Mixed 2 txns

Insider Ostrower Sean William

Role Chief Financial Officer

Type	Security	Shares	Price	Value
Tax Withholding	Class A Common Stock ^F2	15,541	$1.90	$30K
Grant/Award	Class A Common Stock ^F1	299,401	$0.00	$0.00

Holdings After Transaction: Class A Common Stock — 283,860 shares (Direct)

Footnotes (2)

F1. Represents a grant of restricted stock units ("RSUs") on September 28, 2026. The RSUs will vest 1/8 on each of the first eight six-month anniversaries of March 9, 2026. Each RSU represents a contingent right to receive one share of Class A common stock.
F2. Represents shares of Class A Common Stock withheld by the Issuer to satisfy tax withholding upon the vesting of RSUs.

Key Figures

Restricted stock units acquired: 299,401 RSUs RSU share entitlement: 1 Class A common share per RSU Shares withheld for tax withholding: 15,541 Class A common shares +2 more

5 metrics

Restricted stock units acquired 299,401 RSUs September 28, 2026

RSU share entitlement 1 Class A common share per RSU Each RSU is a contingent right to receive one share

Shares withheld for tax withholding 15,541 Class A common shares September 30, 2026

Reported price $1.90 per share Shares withheld on September 30, 2026

RSU vesting schedule 1/8 at each of the first 8 six-month anniversaries Beginning with the first six-month anniversary of March 9, 2026

Key Terms

RSUs, contingent right, tax withholding

3 terms

RSUs financial

"grant of restricted stock units ("RSUs")"

RSUs, or restricted stock units, are a form of company shares given to employees as part of their compensation. They are typically awarded with certain restrictions, such as a waiting period before they can be fully owned or sold, similar to earning a gift that becomes fully yours over time. For investors, RSUs can impact a company's stock offerings and reflect how much the company relies on stock-based incentives to attract and retain talent.

contingent right financial

"Each RSU represents a contingent right to receive one share"

tax withholding financial

"satisfy tax withholding upon the vesting of RSUs"

Tax withholding is the practice of taking a portion of a payment—such as wages, dividends, or sale proceeds—before it reaches the recipient and sending that portion to the tax authority as an advance on the recipient’s eventual tax bill. For investors it matters because withholding reduces immediate cash received and affects after‑tax returns, estimated tax payments, and whether you may owe more or receive a refund when taxes are finally calculated, like having a small automatic savings set aside for your tax bill.

FAQ

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

How many RSUs did AVAT CFO Sean William Ostrower acquire?

Sean William Ostrower, Avalanche Treasury Corp’s chief financial officer, acquired 299,401 restricted stock units on September 28, 2026. Each RSU represents a contingent right to receive one Class A common share. One-eighth vests on each of the first eight six-month anniversaries of March 9, 2026.

How many AVAT shares were withheld for Sean William Ostrower’s RSU taxes?

The issuer withheld 15,541 Class A common shares on September 30, 2026, to satisfy tax withholding upon RSU vesting. The reported price was $1.90 per share.

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

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Available on EDGAR 09/30/2026 - 06:33 PM Accepted by SEC EDGAR 09/30/2026 - 06:33 PM

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^*

Ostrower Sean William

(Last)

(First)

(Middle)

AVALANCHE TREASURY COMPANY, LLC.

11 W. 42ND STREET, 2ND FLOOR

(Street)

NEW YORK

10036

(City)

(State)

(Zip)

UNITED STATES

(Country)

2. Issuer Name and Ticker or Trading Symbol
Avalanche Treasury Corp [ AVAT ]

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

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

2a. Foreign Trading Symbol

3. Date of Earliest Transaction (Month/Day/Year)
09/28/2026

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)
1. Title of Security (Instr. 3)	2. Transaction Date (Month/Day/Year)	2A. Deemed Execution Date, if any (Month/Day/Year)	Code	V	Amount	(A) or (D)	Price		6. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	7. Nature of Indirect Beneficial Ownership (Instr. 4)
Class A Common Stock	09/28/2026		A		299,401⁽¹⁾	A	$0	299,401	D
Class A Common Stock	09/30/2026		F		15,541⁽²⁾	D	$1.9	283,860	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)
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)	Code	V	(A)	(D)	Date Exercisable	Expiration Date	Title	Amount or Number of Shares	8. Price of Derivative Security (Instr. 5)		10. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	11. Nature of Indirect Beneficial Ownership (Instr. 4)

Explanation of Responses:

1. Represents a grant of restricted stock units ("RSUs") on September 28, 2026. The RSUs will vest 1/8 on each of the first eight six-month anniversaries of March 9, 2026. Each RSU represents a contingent right to receive one share of Class A common stock.

2. Represents shares of Class A Common Stock withheld by the Issuer to satisfy tax withholding upon the vesting of RSUs.

	/s/ Laine Mihalchick Moljo, as Attorney-in-Fact	09/30/2026
	** 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)

Source: View Original Filing on SEC EDGAR