[Form 4] Eureka Acquisition Corp Unit Insider Trading Activity

Rhea-AI Filing Summary

Mizuho Securities USA LLC, a 10% beneficial owner of Eureka Acquisition Corp (EURK), filed a Form 4 reporting two open-market transactions.

• 03 Jul 2025: Code S sale of 40,560 common shares at $10.546.
• 07 Jul 2025: Code S sale of 92,000 common shares at $10.540.

The combined disposition totals 132,560 shares, or roughly $1.4 million in gross proceeds, and reduces the insider’s position from 376,557 to 284,557 shares. No derivative activity was reported.

Because the seller is a large holder, the reduction in ownership may be interpreted as a bearish indicator or routine portfolio rebalancing. Investors should watch for additional insider filings or SPAC deal developments that could clarify the owner’s outlook.

Positive

• None.

Negative

• 10% owner reduced stake by 132,560 shares, a roughly 24% decrease, potentially signalling lower confidence.
• Sales executed around trust value ($10.54) may indicate limited perceived upside ahead of a merger.

Insights

Financial Analyst

TL;DR: Significant owner cut stake by 25% via $1.4 M sales; signal skews negative.

The two Code S trades show Mizuho exiting 132,560 shares at ~$10.54, close to SPAC trust value, suggesting limited upside expectations before a business-combination announcement. Post-sale holdings of 284,557 shares keep them above the 10% threshold but mark a noticeable 24% reduction. While one-off sales can be liquidity-driven, the magnitude and short interval warrant caution for investors seeking insider conviction.

Portfolio Manager

TL;DR: Insider selling at par value hints at neutral-to-bearish risk/reward.

SPAC sponsors and early investors often exit near trust value when they lack visibility on deal pipelines. Mizuho’s timing—pre-combination and at marginal premium—implies an opportunistic cash realisation rather than confidence in future appreciation. The filing is impactful because it involves a 10% holder; sustained selling pressure could cap near-term price performance.

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

X

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^*

MIZUHO SECURITIES USA LLC

(Last) (First) (Middle)

1271 AVENUE OF THE AMERICAS

FLOORS - 2,3,4,18,19

(Street)

NEW YORK NY 10020

(City) (State) (Zip)

2. Issuer Name and Ticker or Trading Symbol
Eureka Acquisition Corp [ EURK ]

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

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

3. Date of Earliest Transaction (Month/Day/Year)
07/02/2025

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	07/03/2025	07/03/2025	S		40,560	A	$10.546	376,557	D
Common Stock	07/07/2025	07/07/2025	S		92,000	A	$10.54	284,557	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:

	Gregory Doig	07/15/2025
	** 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.

FAQ

How many Eureka Acquisition (EURK) shares did Mizuho sell?

The Form 4 reports sales of 132,560 common shares.

At what price were the EURK shares sold?

Shares were sold at an average of about $10.54 per share.

What is Mizuho's remaining ownership in EURK after the transactions?

Post-sale, Mizuho beneficially owns 284,557 shares of Eureka Acquisition.

Why is a Form 4 filing important to investors?

Form 4 reveals insider trading activity, which can offer clues about insiders’ confidence and future expectations.

Does Mizuho remain a 10% owner after selling shares?

Yes, despite the reduction, Mizuho’s 284,557 shares still represent at least 10% ownership as stated in the filing.