Rubric Capital discloses 6.56% Ardelyx (ARDX) stake totaling 16.2M shares

Rhea-AI Filing Summary

Rubric Capital Management LP and David Rosen reported beneficial ownership of 16,202,700 shares of Ardelyx, Inc. common stock on a passive ownership basis. This represents 6.56% of Ardelyx’s outstanding common stock, based on 247,029,387 shares outstanding as of April 23, 2026.

The reporting persons have shared voting and dispositive power over all 16,202,700 shares and no sole voting or dispositive power. Rubric Capital Master Fund LP, one of the Rubric funds, has the right to receive or direct dividends and sale proceeds for more than 5% of the common stock.

Key Figures

Shares beneficially owned: 16,202,700 shares Ownership percentage: 6.56 % Shares outstanding: 247,029,387 shares +3 more

6 metrics

Shares beneficially owned 16,202,700 shares Common Stock beneficially owned by the Reporting Persons

Ownership percentage 6.56 % Percent of Ardelyx common stock class owned by the Reporting Persons

Shares outstanding 247,029,387 shares Ardelyx common stock outstanding as of April 23, 2026

Shared voting power 16,202,700.00 shares Shares over which the Reporting Persons have shared voting power

Sole voting power 0.00 shares Shares over which the Reporting Persons have sole voting power

Shared dispositive power 16,202,700.00 shares Shares over which the Reporting Persons have shared dispositive power

Key Terms

beneficial owner, shared voting power, shared dispositive power, investment adviser, +1 more

5 terms

beneficial owner regulatory

"the beneficial owner of the Shares reported herein"

A beneficial owner is the person who ultimately owns or controls a financial asset or property, even if their name isn't directly on official documents. Think of it like someone who secretly holds the keys to a safe deposit box—others may appear to have access, but the true owner is the one who benefits from what's inside. Identifying beneficial owners helps ensure transparency and prevent illegal activities like money laundering or fraud.

shared voting power regulatory

"Shared Voting Power 16,202,700.00"

Shared voting power occurs when two or more parties jointly have the right to vote or decide how a block of company shares is cast, like co-owners who must agree before moving a piece of furniture. Investors care because who controls voting rights affects board elections, major corporate decisions and takeover outcomes, and shared control can alter regulatory disclosures and the practical influence any holder has over a company’s direction and value.

shared dispositive power regulatory

"Shared Dispositive Power 16,202,700.00"

investment adviser financial

"Rubric Capital, the investment adviser to certain investment funds"

An investment adviser is a person or firm that professionally manages money and gives recommendations about buying, selling, or holding investments. Like a financial coach or guide, they have a legal duty to act in a client's best financial interest, so their advice, fees and potential conflicts can directly affect returns and risk — making their role important for investors who want informed, accountable help with portfolios.

percent of class financial

"Percent of class: 6.56 %"

Percent of class is the portion of a specific category of securities—such as a company’s common shares, preferred shares, or a bond series—that takes part in or approves a corporate action (vote, consent, tender, etc.). Investors watch this number because it reveals how much support or opposition exists within that particular shareholder group; like counting how many members of a club back a proposal, it can determine whether a plan passes or how influence is distributed.

FAQ

What percentage of Ardelyx (ARDX) does Rubric Capital Management report owning?

Rubric Capital Management and David Rosen report beneficial ownership of 6.56% of Ardelyx’s common stock, corresponding to 16,202,700 shares, based on 247,029,387 shares outstanding as of April 23, 2026.

How many Ardelyx (ARDX) shares does Rubric Capital Management control voting for?

Rubric Capital Management and David Rosen report shared voting power over 16,202,700 Ardelyx shares and no sole voting power. They also report identical shared dispositive power over the same number of shares.

Who are the reporting persons in this Ardelyx (ARDX) Schedule 13G?

The reporting persons are Rubric Capital Management LP, an investment adviser to certain funds, and David Rosen, Managing Member of Rubric Capital Management GP LLC, the general partner of Rubric Capital Management LP.

What share count did Rubric Capital use to calculate its 6.56% Ardelyx (ARDX) stake?

The 6.56% ownership is based on 247,029,387 Ardelyx common shares outstanding as of April 23, 2026, as reported in Ardelyx’s Form 10-Q for the quarter ended March 31, 2026.

Which Rubric fund has rights to dividends or sale proceeds over Ardelyx (ARDX) shares?

The filing states that Rubric Capital Master Fund LP has the right to receive, or direct the receipt of, dividends and sale proceeds related to more than 5% of Ardelyx’s common stock.

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Available on EDGAR 08/14/2026 - 04:27 PM Accepted by SEC EDGAR 08/14/2026 - 04:03 PM Learn about SEC filing dates

SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

SCHEDULE 13G

UNDER THE SECURITIES EXCHANGE ACT OF 1934

ARDELYX, INC.

(Name of Issuer)

Common Stock, $0.001 par value per share

(Title of Class of Securities)

039697107

(CUSIP Number)

06/30/2026

(Date of Event Which Requires Filing of this Statement)

Check the appropriate box to designate the rule pursuant to which this Schedule is filed:

Rule 13d-1(b)

Rule 13d-1(c)

Rule 13d-1(d)

schemaVersion:

SCHEDULE 13G

CUSIP Number(s): 039697107

1

Names of Reporting Persons

Rubric Capital Management LP

2

Check the appropriate box if a member of a Group (see instructions)

(a)
(b)

3

Sec Use Only

4

Citizenship or Place of Organization

DELAWARE

Number of Shares Beneficially Owned by Each Reporting Person With:

5	Sole Voting Power 0.00
6	Shared Voting Power 16,202,700.00
7	Sole Dispositive Power 0.00
8	Shared Dispositive Power 16,202,700.00

9

Aggregate Amount Beneficially Owned by Each Reporting Person

16,202,700.00

10

Check box if the aggregate amount in row (9) excludes certain shares (See Instructions)

11

Percent of class represented by amount in row (9)

6.56 %

12

Type of Reporting Person (See Instructions)

IA, PN

SCHEDULE 13G

CUSIP Number(s): 039697107

1

Names of Reporting Persons

David Rosen

2

Check the appropriate box if a member of a Group (see instructions)

(a)
(b)

3

Sec Use Only

4

Citizenship or Place of Organization

UNITED STATES

Number of Shares Beneficially Owned by Each Reporting Person With:

5	Sole Voting Power 0.00
6	Shared Voting Power 16,202,700.00
7	Sole Dispositive Power 0.00
8	Shared Dispositive Power 16,202,700.00

9

Aggregate Amount Beneficially Owned by Each Reporting Person

16,202,700.00

10

Check box if the aggregate amount in row (9) excludes certain shares (See Instructions)

11

Percent of class represented by amount in row (9)

6.56 %

12

Type of Reporting Person (See Instructions)

HC, IN

SCHEDULE 13G

Item 1.
(a)	Name of issuer: ARDELYX, INC.
(b)	Address of issuer's principal executive offices: 34175 ARDENWOOD BLVD. Fremont, CA, 94555
Item 2.
(a)	Name of person filing: This statement is filed by: Rubric Capital Management LP ("Rubric Capital"), the investment adviser to certain investment funds and/or accounts (collectively, the "Rubric Funds") that hold the shares of Common Stock, $0.0001 par value per share (the "Common Stock") of Ardelyx, Inc., a Delaware corporation (the "Issuer") reported herein; and David Rosen ("Mr. Rosen"), Managing Member of Rubric Capital Management GP LLC, the general partner of Rubric Capital. The foregoing persons are hereinafter sometimes collectively referred to as the "Reporting Persons." The filing of this statement should not be construed as an admission that any of the forgoing persons or any Reporting Person is, for the purposes of Section 13 of the Act, the beneficial owner of the Shares reported herein.
(b)	Address or principal business office or, if none, residence: The address of the principal business office of each of the Reporting Persons is 155 East 44th St, Suite 1630, New York, NY 10017.
(c)	Citizenship: Rubric Capital is a Delaware limited partnership. Mr. Rosen is a citizen of the United States of America.
(d)	Title of class of securities: Common Stock, $0.001 par value per share
(e)	CUSIP Number(s): 039697107
Item 3.	If this statement is filed pursuant to §§ 240.13d-1(b) or 240.13d-2(b) or (c), check whether the person filing is a:
(a)	Broker or dealer registered under section 15 of the Act (15 U.S.C. 78o);
(b)	Bank as defined in section 3(a)(6) of the Act (15 U.S.C. 78c);
(c)	Insurance company as defined in section 3(a)(19) of the Act (15 U.S.C. 78c);
(d)	Investment company registered under section 8 of the Investment Company Act of 1940 (15 U.S.C. 80a-8);
(e)	An investment adviser in accordance with § 240.13d-1(b)(1)(ii)(E);
(f)	An employee benefit plan or endowment fund in accordance with § 240.13d-1(b)(1)(ii)(F);
(g)	A parent holding company or control person in accordance with § 240.13d-1(b)(1)(ii)(G);
(h)	A savings associations as defined in Section 3(b) of the Federal Deposit Insurance Act (12 U.S.C. 1813);
(i)	A church plan that is excluded from the definition of an investment company under section 3(c)(14) of the Investment Company Act of 1940 (15 U.S.C. 80a-3);
(j)	A non-U.S. institution in accordance with § 240.13d-1(b)(1)(ii)(J). If filing as a non-U.S. institution in accordance with § 240.13d-1(b)(1)(ii)(J), please specify the type of institution:
(k)	Group, in accordance with Rule 240.13d-1(b)(1)(ii)(K).
Item 4.	Ownership
(a)	Amount beneficially owned: The information required by Items 4(a) - (c) is set forth in Rows 9 of the cover page for each of the Reporting Persons and is incorporated herein by reference. The percentage set forth in Row (11) of the cover page for each of the Reporting Persons and in Item 4(b) is based on 247,029,387 shares Common Stock outstanding as of April 23, 2026, as reported in the Issuer's Quarterly Report on Form 10-Q for the quarterly period ended March 31, 2026 filed with the Securities and Exchange Commission on April 30, 2026.
(b)	Percent of class: 6.56 %
(c)	Number of shares as to which the person has:
	(i) Sole power to vote or to direct the vote: The information required by Item 4(c)(i) is set forth in Row 5 of the cover page for each of the Reporting Persons and is incorporated herein by reference.
	(ii) Shared power to vote or to direct the vote: The information required by Item 4(c)(ii) is set forth in Row 6 of the cover page for each of the Reporting Persons and is incorporated herein by reference.
	(iii) Sole power to dispose or to direct the disposition of: The information required by Item 4(c)(iii) is set forth in Row 7 of the cover page for each of the Reporting Persons and is incorporated herein by reference.
	(iv) Shared power to dispose or to direct the disposition of: The information required by Item 4(c)(iv) is set forth in Row 8 of the cover page for each of the Reporting Persons and is incorporated herein by reference.
Item 5.	Ownership of 5 Percent or Less of a Class.
	Not Applicable
Item 6.	Ownership of more than 5 Percent on Behalf of Another Person.
	If any other person is known to have the right to receive or the power to direct the receipt of dividends from, or the proceeds from the sale of, such securities, a statement to that effect should be included in response to this item and, if such interest relates to more than 5 percent of the class, such person should be identified. A listing of the shareholders of an investment company registered under the Investment Company Act of 1940 or the beneficiaries of employee benefit plan, pension fund or endowment fund is not required. See Item 2(a). Rubric Capital Master Fund LP, a Rubric Fund, has the right to receive or the power to direct the receipt of dividends from, or the proceeds from the sale of, more than 5% of the Common Stock.
Item 7.	Identification and Classification of the Subsidiary Which Acquired the Security Being Reported on by the Parent Holding Company or Control Person.
	Not Applicable
Item 8.	Identification and Classification of Members of the Group.
	Not Applicable
Item 9.	Notice of Dissolution of Group.
	Not Applicable

Item 10.

Certifications:

By signing below I certify that, to the best of my knowledge and belief, the securities referred to above were acquired and are held in the ordinary course of business and were not acquired and are not held for the purpose of or with the effect of changing or influencing the control of the issuer of the securities and were not acquired and are not held in connection with or as a participant in any transaction having that purpose or effect, other than activities solely in connection with a nomination under § 240.14a-11.

SIGNATURE

After reasonable inquiry and to the best of my knowledge and belief, I certify that the information set forth in this statement is true, complete and correct.

Rubric Capital Management LP

Signature:	/s/ Michael Nachmani
Name/Title:	Michael Nachmani / Chief Operating Officer
Date:	08/14/2026

David Rosen

Signature:	/s/ David Rosen
Name/Title:	David Rosen / Individually
Date:	08/14/2026

Exhibit Information

Exhibit 99.1: Joint Filing Agreement