[SCHEDULE 13G/A] Masimo Corporation SEC Filing

Rhea-AI Filing Summary

Joe Kiani reports beneficial ownership of 6,583,783 shares of Masimo Corporation common stock, representing 11.4% of the class using a base of 54,324,812 shares outstanding. The position combines shares held directly, shares held in trusts, retirement-plan shares and multiple equity awards and options.

A substantial portion of the reported holdings is the subject of active dispute: the filing includes 368,252 shares from exercised options the company declined to process, a claimed 2,700,000-share RSU award, 158,450 accelerated options, 198,225 performance RSUs (PSUs) and 85,255 vested options that the issuer contends were cancelled. The issuer has filed claims in the Court of Chancery of the State of Delaware challenging entitlement to some awards; the reporting person disputes the issuer’s position.

The reporting person discloses sole voting and dispositive power over 6,545,048 shares and shared voting and dispositive power over 38,735 shares, and states the reporting person’s spouse is entitled to receive dividends and sale proceeds for certain shares.

Positive

• Declared beneficial ownership of 6,583,783 shares, representing 11.4% of the class based on the filer’s calculation
• Sole voting/dispositive power over 6,545,048 shares, indicating substantial direct control over the majority of reported holdings
• Detailed, transparent breakdown of ownership categories including trusts, retirement-plan shares and specific award types

Negative

• Large components of the reported position are disputed: including 2,700,000 RSUs, 368,252 exercised options, 158,450 accelerated options, 198,225 PSUs and 85,255 vested options that the issuer contends are cancelled or not issuable
• Issuer declined to process option exercises and alleges the reporting person was terminated for "cause," creating contested entitlement to shares
• Issuer filed claims in the Court of Chancery of the State of Delaware seeking declarations challenging the reporting person’s entitlement to certain awards, introducing legal uncertainty over final ownership and potential voting outcomes

Insights

Securities Analyst

TL;DR Founder-level ownership of 11.4% is reported but tangled with large disputed awards and unissued shares that create ownership uncertainty.

The filing quantifies a significant stake and discloses that 2.7 million RSUs plus several option pools and exercised-option shares are being counted by the reporting person despite the issuer declining to issue some awards. The Schedule bases the percentage on 54,324,812 shares outstanding and explicitly adds issuable shares tied to disputed awards. For investors, the key takeaway is that headline ownership may change depending on the Delaware Court of Chancery actions and the company’s processing of exercises; until disputes resolve, the practical number of issued shares and related voting rights remain uncertain.

Corporate Governance Expert

TL;DR The filing signals both founder alignment through concentrated holdings and a material governance dispute over equity awards.

The report categorizes holdings across direct ownership, trust holdings and multiple classes of equity awards, some of which the issuer alleges were invalidated by a termination-for-cause determination. The issuer has filed claims in Delaware seeking declarations about entitlement to awards, while the reporting person maintains the awards should have been issued or accelerated under his employment agreement. This raises governance questions about award administration, contractual interpretation and potential future changes to voting power depending on litigation outcomes.

SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

SCHEDULE 13G

UNDER THE SECURITIES EXCHANGE ACT OF 1934

(Amendment No. 18)

Masimo Corporation

(Name of Issuer)

Common Stock, $0.0001 par value

(Title of Class of Securities)

574795100

(CUSIP Number)

06/30/2025

(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)

SCHEDULE 13G

CUSIP No. 574795100

1

Names of Reporting Persons

Joe Kiani

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 6,545,048.00
6	Shared Voting Power 38,735.00
7	Sole Dispositive Power 6,545,048.00
8	Shared Dispositive Power 38,735.00

9

Aggregate Amount Beneficially Owned by Each Reporting Person

6,583,783.00

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)

11.4 %

12

Type of Reporting Person (See Instructions)

IN

Comment for Type of Reporting Person: (1) Aggregate amount beneficially owned is comprised of (a) 100,000 shares of the Issuer's common stock held in the name of the Reporting Person, (b) 1,736,547 shares of the Issuer's common stock held in two trusts for which the Reporting Person is the sole trustee, (c) 1,226,688 shares of the Issuer's common stock held in three trusts for which the Reporting Person is not the trustee, (d) 38,735 shares of the Issuer's common stock held by the Reporting Person's spouse, (e) 10,366 shares of the Issuer's common stock held for the Reporting Person's account under the Issuer's Retirement Savings Plan, (f) 368,252 shares of the Issuer's common stock subject to the Exercised Options (as defined in Footnote (1) to Item 4(a) below) that are subject to a dispute between the Issuer and the Reporting Person as described in Footnote (1) to Item 4(a) below, (g) 2,700,000 shares of the Issuer's common stock that are subject to the RSU Award (as defined in Footnote (2) to Item 4(a) below) that is subject to a dispute between the Issuer and the Reporting Person as further described in Footnote (2) to Item 4(a) below, (h) 158,450 shares of the Issuer's common stock subject to the Accelerated Options (as defined in Footnote (3) to Item 4(a) below) that are subject to a dispute between the Issuer and the Reporting Person as described in Footnote (3) to Item 4(a) below, (i) 198,225 shares of the Issuer's common stock subject to the PSUs (as defined in Footnote (4) to Item 4(a) below) that are subject to a dispute between the Issuer and the Reporting Person as described in Footnote (4) to Item 4(a) below, and (j) 85,255 shares of the Issuer's common stock subject to the Vested Options (as defined in Footnote (5) to Item 4(a) below) that are subject to a dispute between the Issuer and the Reporting Person as described in Footnote (5) to Item 4(a) below. (2) Percent of class was calculated based on: (a) 54,324,812 shares of the Issuer's common stock outstanding as of June 28, 2025 (as reported in the Issuer's Quarterly Report on Form 10-Q for the quarterly period ended June 28, 2025 filed with the Securities and Exchange Commission on August 5, 2025), (b) 368,252 shares of the Issuer's common stock issuable upon exercise of the Exercised Options that have not yet been issued by the Issuer to the Reporting Person, (c) 2,700,000 shares of the Issuer's common stock issuable underlying the RSU Award that have not yet been issued by the Issuer to the Reporting Person, (d) 158,450 shares of the Issuer's common stock issuable upon exercise of the Accelerated Options that should have been deemed vested in full on October 24, 2024, (e) 198,225 shares of the Issuer's common stock subject to the PSUs that should have been accelerated and issued by the Issuer to the Reporting Person on October 24, 2024, and (f) 85,255 shares of the Issuer's common stock subject to the Vested Options.

SCHEDULE 13G

Item 1.
(a)	Name of issuer: Masimo Corporation
(b)	Address of issuer's principal executive offices: 52 Discovery, Irvine, CA 92618
Item 2.
(a)	Name of person filing: Joe Kiani
(b)	Address or principal business office or, if none, residence: 121 Theory, Irvine, CA 92617
(c)	Citizenship: United States
(d)	Title of class of securities: Common Stock, $0.0001 par value
(e)	CUSIP No.: 574795100
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: 6,583,783 shares of the Issuer's common stock, which is comprised of (a) 100,000 shares of the Issuer' held in the name of the Reporting Person, (b) 1,736,547 shares held in two trusts for which the Reporting Person is the sole trustee, (c) 1,226,688 shares held in three trusts for which the Reporting Person is not the trustee, (d) 38,735 shares held by the Reporting Person's spouse, (e) 10,366 shares held for the Reporting Person's account under the Issuer's Retirement Savings Plan, (f) 368,252 shares subject to the Exercised Options (as defined in Footnote (1) below) that are subject to a dispute between the Issuer and the Reporting Person as described in Footnote (1) below, (g) 2,700,000 shares that are subject to the RSU Award (as defined in Footnote (2) below) that is subject to a dispute between the Issuer and the Reporting Person as further described in Footnote (2) below, (h) 158,450 shares subject to the Accelerated Options (as defined in Footnote (3) below) that are subject to a dispute between the Issuer and the Reporting Person as described in Footnote (3) below, (i) 198,225 shares subject to the PSUs (as defined in Footnote (4) below) that are subject to a dispute between the Issuer and the Reporting Person as described in Footnote (4) below, and (j) 85,255 shares subject to the Vested Options (as defined in Footnote (5) below) that are subject to a dispute between the Issuer and the Reporting Person as described in Footnote (5) below. Footnotes: (1) On January 17, 2025, the Reporting Person provided the Issuer with completed notices of exercise and shares of the Issuer's common stock sufficient to satisfy the payment of the aggregate cash exercise price for the exercise of an aggregate of 368,252 shares of the Issuer's common stock (the "Exercised Options"). The Issuer declined to process the Reporting Person's exercise notices, alleging that the Reporting Person had been terminated with "cause" and that the Exercised Options had been cancelled and could not be exercised by the Reporting Person. The Reporting Person disagrees with the characterization that the Reporting Person's employment was terminated for "cause" or that the Exercised Options were cancelled or could not be exercised. The Reporting Person believes that the exercise notices for the Exercised Options should have been processed and that the Reporting Person should have been issued 368,252 shares of the Issuer's common stock upon exercise of the Exercised Options on January 17, 2025. Therefore, the Reporting Person has included the 368,252 shares of the Issuer's common stock subject to the Exercised Options as beneficially owned in this Schedule 13G/A even though the shares have not yet been issued to the Reporting Person. (2) In November 2015, the Issuer entered into an Amended and Restated Employment Agreement (the "Employment Agreement") with the Reporting Person, which provided, among other things, that upon a Qualifying Termination (as defined in the Employment Agreement), the Issuer would be obligated to issue the Reporting Person 2,700,000 shares of the Issuer's common stock pursuant to the terms of an RSU award agreement between the Issuer and the Reporting Person (the "RSU Award"). The Reporting Person's position is that a Qualifying Termination occurred pursuant to the Employment Agreement and that the Reporting Person should have been issued the 2,700,000 shares of the Issuer's common stock pursuant to the terms of the Employment Agreement and the RSU Award; however, the Issuer has not yet issued such shares to the Reporting Person and has filed claims against the Reporting Person in the Court of Chancery of the State of Delaware, seeking judicial declarations that, among other things, the Reporting Person is not entitled to receive the shares subject to the RSU Award. As the Reporting Person believes that the Issuer should have issued the 2,700,000 shares of the Issuer's common stock subject to the RSU Award to the Reporting Person, the Reporting Person has included the 2,700,000 shares of the Issuer's common stock as beneficially owned in this Schedule 13G/A even though the shares have not yet been issued to the Reporting Person. (3) The Employment Agreement also provided that all of the Reporting Person's stock options and other equity awards would vest, effective as of immediately prior to a Qualifying Termination. As of October 24, 2024, the last day of the Reporting Person's employment by the Issuer, the Reporting Person held unvested options to purchase an aggregate of 158,450 shares of the Issuer's common stock (the "Accelerated Options"). As noted above, the Reporting Person's position is that a Qualifying Termination occurred pursuant to the Employment Agreement and that the Issuer should have accelerated the vesting for the Accelerated Options in accordance with the Employment Agreement. Moreover, the Reporting Person's position is that the Employment Agreement provides that the Accelerated Options remain outstanding through their respective dates of expiration, which is ten years after the applicable grant date. Therefore, the Reporting Person has included 158,450 shares of the Issuer's common stock as beneficially owned in this Schedule 13G/A even though the Issuer did not accelerate the vesting for the Accelerated Options or make them available for exercise by the Reporting Person. In including the Accelerated Options in this Schedule 13G/A, the Reporting Person neither asserts nor denies beneficial ownership of the shares of Common Stock underlying the Accelerated Options but has included them herein for transparency. (4) As noted above, the Employment Agreement provided that all of the Reporting Person's stock options and other equity awards would vest, effective as of immediately prior to a Qualifying Termination. As of October 24, 2024, the last day of the Reporting Person's employment by the Issuer, the Reporting Person held performance restricted stock unit awards with respect to an aggregate target number of shares of the Issuer's common stock equal to 198,225 shares of the Issuer's common stock (the "PSUs"). As noted above, the Reporting Person's position is that a Qualifying Termination occurred pursuant to the Employment Agreement and that the Issuer should have accelerated the vesting for the PSUs at target in accordance with the Employment Agreement. Therefore, the Reporting Person has included 198,225 shares of the Issuer's common stock as beneficially owned in this Schedule 13G/A even though the Issuer did not accelerate the vesting for the PSUs or issue the target number of shares with respect to the PSUs on October 24, 2024. (5) As of October 24, 2024, the last day of the Reporting Person's employment by the Issuer, the Reporting Person held vested options to purchase an aggregate of 85,255 shares of the Issuer's common stock that were not among the Exercised Options or subsequently exercised by the Reporting Person (such options, the "Vested Options"). As noted above, the Issuer has alleged that the Reporting Person had been terminated with "cause" and that the Vested Options have been cancelled and cannot be exercised by the Reporting Person. However, the Reporting Person's position is that the Employment Agreement provides that the Vested Options remain outstanding through their respective dates of expiration, which is ten years after the applicable grant date. Therefore, the Reporting Person has included 85,255 shares of the Issuer's common stock as beneficially owned in this Schedule 13G/A even though the Issuer has asserted that the Vested Options have been cancelled. In including the Vested Options in this Schedule 13G/A, the Reporting Person neither asserts nor denies beneficial ownership of the shares of Common Stock underlying such options but has included them herein for transparency.
(b)	Percent of class: 11.4%; calculated based on: (a) 54,324,812 shares of the Issuer's common stock outstanding as of June 28, 2025 (as reported in the Issuer's Quarterly Report on Form 10-Q for the quarterly period ended June 28, 2025 filed with the Securities and Exchange Commission on August 5, 2025), (b) 368,252 shares of the Issuer's common stock issuable upon exercise of the Exercised Options that have not yet been issued by the Issuer to the Reporting Person, (c) 2,700,000 shares of the Issuer's common stock issuable underlying the RSU Award that have not yet been issued by the Issuer to the Reporting Person, (d) 158,450 shares of the Issuer's common stock issuable upon exercise of the Accelerated Options that should have been deemed vested in full on October 24, 2024, (e) 198,225 shares of the Issuer's common stock subject to the PSUs that should have been accelerated and issued by the Issuer to the Reporting Person on October 24, 2024, and (f) 85,255 shares of the Issuer's common stock subject to the Vested Options.
(c)	Number of shares as to which the person has:
	(i) Sole power to vote or to direct the vote: 6,545,048
	(ii) Shared power to vote or to direct the vote: 38,735
	(iii) Sole power to dispose or to direct the disposition of: 6,545,048
	(iv) Shared power to dispose or to direct the disposition of: 38,735
Item 5.	Ownership of 5 Percent or Less of a Class.
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. The Reporting Person's spouse described in Item 4 is entitled to receive dividends and sale proceeds.
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:
	Not Applicable

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.

Joe Kiani

Signature:	/s/ Joe Kiani
Name/Title:	Individual
Date:	08/12/2025

Exhibit Information

N/A

FAQ

How many Masimo (MASI) shares does Joe Kiani report owning?

The filing states 6,583,783 shares of common stock, described as representing 11.4% of the class.

How was the 11.4% ownership percentage calculated for MASI?

The percentage is calculated using 54,324,812 shares outstanding and includes certain issuable shares from exercised options, RSUs, accelerated options, PSUs and vested options enumerated in the filing.

Which specific share awards are in dispute in the MASI filing?

The filing identifies disputed components: 368,252 shares from exercised options, a claimed 2,700,000-share RSU award, 158,450 accelerated options, 198,225 PSUs and 85,255 vested options.

Has Masimo taken legal action regarding these awards?

Yes. The filing states the issuer has filed claims in the Court of Chancery of the State of Delaware seeking declarations that the reporting person is not entitled to receive certain shares.

How many MASI shares does Joe Kiani have sole voting power over?

The filing discloses sole voting power over 6,545,048 shares and shared voting power over 38,735 shares.

Does anyone else have rights to dividends or sale proceeds for the reported MASI shares?

Yes. The filing discloses that the reporting person’s spouse is entitled to receive dividends and sale proceeds for shares described in Item 4.