Masimo (MASI) bought out for $180 per share as Politan exits stake

Rhea-AI Filing Summary

Masimo Corporation completed its merger on June 10, 2026, cashing out all common shareholders. At the merger’s effective time, each share of Masimo common stock was cancelled and converted into the right to receive $180.00 in cash per share, before taxes.

The reporting group led by Politan Capital Management held 4,590,873 shares, which were converted into the cash merger consideration, and Quentin Koffey’s 1,119 restricted share units were also cancelled for the same per‑share cash amount. Following this transaction, all reporting persons now report 0 shares and 0.0% beneficial ownership of Masimo, with no remaining voting or dispositive power.

Insights

Event-driven equity analyst

Filing confirms Masimo’s cash sale at $180 per share and ends Politan’s stake.

This amendment to the Schedule 13D documents the closing of Masimo’s merger and specifies that all common shares were converted into a cash entitlement of $180.00 per share. It also confirms that Masimo is now a wholly owned subsidiary of the acquiring parent.

The Politan-led group’s 4,590,873 shares and Quentin Koffey’s 1,119 restricted share units converted into the cash consideration, leaving the group with no remaining beneficial ownership or voting power. The filing is largely confirmatory; economic implications for investors come from the previously agreed merger terms rather than this administrative update.

Key Figures

Per Share Merger Consideration: $180.00 per share Shares held by reporting group: 4,590,873 shares Restricted share units: 1,119 RSUs +4 more

7 metrics

Per Share Merger Consideration $180.00 per share Cash paid for each Masimo common share at merger

Shares held by reporting group 4,590,873 shares Masimo common shares beneficially owned before merger

Restricted share units 1,119 RSUs Masimo RSUs held by Quentin Koffey converted to cash

Beneficial ownership after merger 0 shares Each reporting person’s Masimo holdings post-merger

Percent of class after merger 0.0% Percent of Masimo common stock owned by each reporter

Amendment number Amendment No. 17 Latest amendment to Schedule 13D for Masimo

Merger closing date June 10, 2026 Closing date and effective time of Masimo merger

Key Terms

Per Share Merger Consideration, Merger Agreement, Effective Time, restricted share units, +2 more

6 terms

Per Share Merger Consideration financial

"converted into the right to receive an amount in cash equal to $180.00 per share"

Merger Agreement regulatory

"the Merger was consummated pursuant to the Merger Agreement"

A merger agreement is a binding contract that lays out the exact terms for two companies to combine, including the price, what each side will deliver, and the conditions that must be met before the deal is completed. Investors care because it sets the timetable, payouts and risks — like a blueprint or prenup that shows whether the deal is likely to close, how ownership will change, and what could cancel or alter the payout they expect.

Effective Time regulatory

"At the effective time of the Merger (the "Effective Time"), Merger Sub merged"

restricted share units financial

"the 1,119 restricted share units held by Mr. Koffey ... were cancelled and converted"

Restricted share units (RSUs) are a promise from a company to give an employee or service provider actual shares or cash equal to the shares after certain conditions are met, typically staying with the company for a set time or hitting performance targets. Think of them like a time-locked gift card that becomes usable only after you’ve earned it. For investors, RSUs matter because they align employee incentives with company performance and can increase the number of shares outstanding over time, diluting existing ownership and affecting earnings per share.

beneficially own regulatory

"the Reporting Persons ceased to beneficially own any shares of Common Stock"

Beneficially own means having the economic rights and risks of a security—such as the right to receive dividends, sell the shares, or profit from price changes—whether or not your name appears on the official share register. Think of it like renting a car: you use it and reap the benefits even if the title lists someone else. Investors care because beneficial ownership determines who truly controls value, must be disclosed under securities rules, and can signal potential influence or trading activity that affects a stock’s price.

sole or shared power to vote regulatory

"no sole or shared power to vote or to direct the vote"

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SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

SCHEDULE 13D

Under the Securities Exchange Act of 1934

(Amendment No. 17)

MASIMO CORP

(Name of Issuer)

Common Stock, par value $0.001 per share

(Title of Class of Securities)

574795100

(CUSIP Number)

Quentin Koffey
Politan Capital Management LP, 106 West 56th Street, 10th Floor
New York, NY, 10019
646-690-2830

(Name, Address and Telephone Number of Person Authorized to Receive Notices and Communications)

06/10/2026

(Date of Event Which Requires Filing of This Statement)

If the filing person has previously filed a statement on Schedule 13G to report the acquisition that is the subject of this Schedule 13D, and is filing this schedule because of §§ 240.13d-1(e), 240.13d-1(f) or 240.13d-1(g), check the following box.

The information required on the remainder of this cover page shall not be deemed to be "filed" for the purpose of Section 18 of the Securities Exchange Act of 1934 ("Act") or otherwise subject to the liabilities of that section of the Act but shall be subject to all other provisions of the Act (however, see the Notes).

schemaVersion:

SCHEDULE 13D

CUSIP Number(s): 574795100

1

Name of reporting person

Politan Capital Management LP

2

Check the appropriate box if a member of a Group (See Instructions)

(a)
(b)

3

SEC use only

4

Source of funds (See Instructions)

OO

5

Check if disclosure of legal proceedings is required pursuant to Items 2(d) or 2(e)

6

Citizenship or place of organization

DELAWARE

Number of Shares Beneficially Owned by Each Reporting Person With:

7	Sole Voting Power 0.00
8	Shared Voting Power 0.00
9	Sole Dispositive Power 0.00
10	Shared Dispositive Power 0.00

11

Aggregate amount beneficially owned by each reporting person

0.00

12

Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)

13

Percent of class represented by amount in Row (11)

0 %

14

Type of Reporting Person (See Instructions)

IA

SCHEDULE 13D

CUSIP Number(s): 574795100

1

Name of reporting person

Politan Capital Management GP LLC

2

Check the appropriate box if a member of a Group (See Instructions)

(a)
(b)

3

SEC use only

4

Source of funds (See Instructions)

OO

5

Check if disclosure of legal proceedings is required pursuant to Items 2(d) or 2(e)

6

Citizenship or place of organization

DELAWARE

Number of Shares Beneficially Owned by Each Reporting Person With:

7	Sole Voting Power 0.00
8	Shared Voting Power 0.00
9	Sole Dispositive Power 0.00
10	Shared Dispositive Power 0.00

11

Aggregate amount beneficially owned by each reporting person

0.00

12

Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)

13

Percent of class represented by amount in Row (11)

0 %

14

Type of Reporting Person (See Instructions)

IA

SCHEDULE 13D

CUSIP Number(s): 574795100

1

Name of reporting person

Politan Capital Partners GP LLC

2

Check the appropriate box if a member of a Group (See Instructions)

(a)
(b)

3

SEC use only

4

Source of funds (See Instructions)

OO

5

Check if disclosure of legal proceedings is required pursuant to Items 2(d) or 2(e)

6

Citizenship or place of organization

DELAWARE

Number of Shares Beneficially Owned by Each Reporting Person With:

7	Sole Voting Power 0.00
8	Shared Voting Power 0.00
9	Sole Dispositive Power 0.00
10	Shared Dispositive Power 0.00

11

Aggregate amount beneficially owned by each reporting person

0.00

12

Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)

13

Percent of class represented by amount in Row (11)

0 %

14

Type of Reporting Person (See Instructions)

IA

SCHEDULE 13D

CUSIP Number(s): 574795100

1

Name of reporting person

Quentin Koffey

2

Check the appropriate box if a member of a Group (See Instructions)

(a)
(b)

3

SEC use only

4

Source of funds (See Instructions)

OO

5

Check if disclosure of legal proceedings is required pursuant to Items 2(d) or 2(e)

6

Citizenship or place of organization

UNITED STATES

Number of Shares Beneficially Owned by Each Reporting Person With:

7	Sole Voting Power 0.00
8	Shared Voting Power 0.00
9	Sole Dispositive Power 0.00
10	Shared Dispositive Power 0.00

11

Aggregate amount beneficially owned by each reporting person

0.00

12

Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)

13

Percent of class represented by amount in Row (11)

0 %

14

Type of Reporting Person (See Instructions)

IN

SCHEDULE 13D

Item 1.	Security and Issuer
(a)	Title of Class of Securities: Common Stock, par value $0.001 per share
(b)	Name of Issuer: MASIMO CORP
(c)	Address of Issuer's Principal Executive Offices: 52 DISCOVERY, IRVINE, CALIFORNIA , 92618.
Item 1 Comment: This Amendment No. 17 to Schedule 13D (this "Amendment No. 17") amends and supplements the Schedule 13D filed on August 16, 2022 (as amended and supplemented through the date of this Amendment No. 17, collectively, the "Schedule 13D") by the Reporting Persons, relating to the common stock, par value $0.001 per share, of Masimo Corporation, a Delaware corporation (the "Issuer"). Capitalized terms not defined in this Amendment No. 17 shall have the meaning ascribed to them in the Schedule 13D.
Item 4.	Purpose of Transaction
	Item 4 is hereby amended and supplemented as follows: On June 10, 2026 (the "Closing Date"), the Merger was consummated pursuant to the Merger Agreement. At the effective time of the Merger (the "Effective Time"), Merger Sub merged with and into the Issuer, with the Issuer continuing as the surviving corporation and a wholly owned subsidiary of Parent. At the Effective Time, each share of Common Stock issued and outstanding immediately prior to the Effective Time (other than shares excluded or treated as described in the Merger Agreement) was automatically cancelled, extinguished and converted into the right to receive an amount in cash equal to $180.00 per share, without interest and less any applicable withholding taxes (the "Per Share Merger Consideration"). Accordingly, the 4,590,873 shares of Common Stock beneficially owned by the Reporting Persons immediately prior to the Effective Time were converted into the right to receive the Per Share Merger Consideration. In addition, the 1,119 restricted share units held by Mr. Koffey, as a non-employee director of the Issuer, were cancelled and converted at the Effective Time into the right to receive an amount in cash equal to the Per Share Merger Consideration for each share of Common Stock underlying such restricted share units. As a result of the Merger, the Reporting Persons ceased to beneficially own any shares of Common Stock.
Item 5.	Interest in Securities of the Issuer
(a)	Item 5(a) is hereby amended and restated in its entirety as follows: As a result of the consummation of the Merger, as described in Item 4, each Reporting Person ceased to beneficially own any shares of Common Stock. See rows (11) and (13) of the cover pages to this Amendment No. 17, which reflect zero shares of Common Stock and 0.0% beneficially owned by each Reporting Person.
(b)	Item 5(b) is hereby amended and restated in its entirety as follows: (b) See rows (7) through (10) of the cover pages to this Amendment No. 17. Each Reporting Person has no sole or shared power to vote or to direct the vote, and no sole or shared power to dispose or to direct the disposition, of any shares of Common Stock.
(c)	Item 5(c) is hereby amended and restated in its entirety as follows: Except as set forth in Item 4, which is incorporated herein by reference, the Reporting Persons have not effected any transactions in the Common Stock during the past sixty (60) days.
(e)	June 10, 2026
Item 6.	Contracts, Arrangements, Understandings or Relationships With Respect to Securities of the Issuer
	Item 6 is hereby amended and restated as follows: The information provided or incorporated by reference in Item 4 is hereby incorporated by reference herein.

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.

Politan Capital Management LP

Signature:	/s/ Quentin Koffey
Name/Title:	Quentin Koffey, Managing Member
Date:	06/11/2026

Politan Capital Management GP LLC

Signature:	/s/ Quentin Koffey
Name/Title:	Quentin Koffey, Managing Member
Date:	06/11/2026

Politan Capital Partners GP LLC

Signature:	/s/ Quentin Koffey
Name/Title:	Quentin Koffey, Managing Member
Date:	06/11/2026

Quentin Koffey

Signature:	/s/ Quentin Koffey
Name/Title:	Quentin Koffey
Date:	06/11/2026

FAQ

What does the Masimo (MASI) Schedule 13D/A Amendment No. 17 report?

It reports that Masimo’s merger closed and all common shares were converted into cash at $180.00 per share. The reporting investors, led by Politan Capital Management, now hold 0 shares and no longer have any voting or dispositive power.

What cash amount did Masimo (MASI) shareholders receive in the merger?

Each Masimo common share was converted into the right to receive $180.00 in cash per share, before any applicable withholding taxes. This amount, called the Per Share Merger Consideration, applied to all issued and outstanding shares not otherwise excluded.

How many Masimo shares were held by the Politan group before the merger?

The reporting persons beneficially owned 4,590,873 Masimo common shares immediately before the merger’s effective time. All of these shares were cancelled and converted into the right to receive the $180.00 per share cash merger consideration upon closing.

What happened to Quentin Koffey’s Masimo restricted share units in the merger?

Quentin Koffey held 1,119 restricted share units as a non‑employee director. At the merger’s effective time, these units were cancelled and converted into a cash right equal to the $180.00 per share merger consideration for each underlying Masimo share.

Do the Politan reporting persons still own any Masimo (MASI) shares?

No. After the merger closed on June 10, 2026, each reporting person ceased to beneficially own any Masimo common shares. The filing shows 0 shares and 0.0% beneficial ownership, with no voting or dispositive power remaining.

What corporate change did this Masimo transaction trigger?

The merger combined Masimo with a parent entity, making Masimo a wholly owned subsidiary of that parent. All publicly held common stock was cancelled and converted into a cash right at $180.00 per share, effectively ending Masimo’s separate public float.