Document

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

WASHINGTON, D.C. 20549

SCHEDULE 14A INFORMATION

Proxy Statement Pursuant to Section 14(a) of the

Securities Exchange Act of 1934

(Amendment No. )

Filed by the Registrant ý Filed by a Party other than the Registrant o

Check the appropriate box:

Preliminary Proxy Statement

Confidential, for Use of the Commission Only (as permitted by Rule 14a-6(e)(2))

Definitive Proxy Statement

Definitive Additional Materials

Soliciting Material Pursuant to §240.14a-12

MASIMO CORPORATION

(Name of Registrant as Specified In Its Charter)

(Name of Person(s) Filing Proxy Statement, if other than the Registrant)

Payment of Filing Fee (Check the appropriate box):

No fee required.

Fee paid previously with preliminary materials.

Fee computed on table in exhibit required by Item 25(b) per Exchange Act Rules 14a-6(i)(1) and 0-11.

Persons who are to respond to the collection of information contained in this form are not required to respond unless the form displays a currently valid OMB control number.

On June 22, 2023, Masimo Corporation updated its website at www.KeepMasimoStrong.com, which contains information relating to Masimo’s 2023 Annual Meeting of Stockholders. A copy of the updated website content (other than that previously filed) can be found below.

Forward-Looking Statements

This communication includes forward-looking statements as defined in Section 27A of the Securities Act of 1933 and Section 21E of the Securities Exchange Act of 1934, as amended, in connection with the Private Securities Litigation Reform Act of 1995. These forward-looking statements are based on current

expectations about future events affecting us and are subject to risks and uncertainties, all of which are difficult to predict and many of which are beyond our control and could cause our actual results to differ materially and adversely from those expressed in our forward-looking statements as a result of various risk factors, including, but not limited to those described in this communication and other factors discussed in the “Risk Factors” section of our most recent reports filed with the Securities and Exchange Commission (“SEC”), which may be obtained for free at the SEC’s website at www.sec.gov. Although we believe that the expectations reflected in these forward-looking statements are reasonable, we do not know whether our expectations will prove correct. All forward-looking statements included in this communication are expressly qualified in their entirety by the foregoing cautionary statements. You are cautioned not to place undue reliance on these forward-looking statements, which speak only as of today’s date. We do not undertake any obligation to update, amend or clarify these statements or the “Risk Factors” contained in our most recent reports filed with the SEC, whether as a result of new information, future events or otherwise, except as may be required under the applicable securities laws.

Additional Information Regarding The Annual Meeting of Stockholders Currently Expected to Be Held on June 26, 2023 and Where to Find It

Masimo has filed a definitive proxy statement containing a form of WHITE proxy card with the SEC in connection with its solicitation of proxies for its 2023 Annual Meeting of Stockholders. MASIMO’S SHAREHOLDERS ARE STRONGLY ENCOURAGED TO READ THE DEFINITIVE PROXY STATEMENT (AND ANY AMENDMENTS AND SUPPLEMENTS THERETO) AND ACCOMPANYING WHITE PROXY CARD AS THEY WILL CONTAIN OR CONTAIN IMPORTANT INFORMATION. Stockholders may obtain the proxy statement, any amendments or supplements to the proxy statement and other documents as and when filed by Masimo with the SEC without charge from the SEC’s website at www.sec.gov.

Certain Information Regarding Participants

Masimo, its directors and certain of its executive officers may be deemed to be participants in connection with the solicitation of proxies from Masimo’s stockholders in connection with the matters to be considered at the 2023 Annual Meeting of Stockholders. Information regarding the ownership of Masimo’s directors and executive officers in Masimo common shares is included in Masimo’s definitive proxy statement, which can be found through the SEC’s website at www.sec.gov. To the extent holdings of Masimo’s securities by directors or executive officers have changed since the amounts set forth in the definitive proxy statement, such changes have been or will be reflected on SEC filings filed by the applicable individuals on Forms 3, 4, and 5, which can be found through the SEC’s website at www.sec.gov. These documents can be obtained free of charge from the sources indicated above.