SCHEDULE 14A
(Rule 14A-101)

INFORMATION REQUIRED IN PROXY STATEMENT
SCHEDULE 14A INFORMATION

Proxy Statement Pursuant to Section 14(a) of the
Securities Exchange Act of 1934

Filed by the Registrant ☒ Filed by a Party other than the Registrant ☐

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 under §240.14a-12

ULTRA CLEAN HOLDINGS, INC.
(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 computed on table below per Exchange Act Rules 14a-6(i)(4) and 0-11.

1. Title of each class of securities to which transaction applies:

2. Aggregate number of securities to which transaction applies:

3. Per unit price or other underlying value of transaction computed pursuant to Exchange Act Rule 0-11 (set forth the amount on which the filing fee is calculated and state how it was determined):

4. Proposed maximum aggregate value of transaction:

5. Total fee paid:

☐ Fee paid previously with preliminary materials.

☐ Check box if any part of the fee is offset as provided by Exchange Act Rule 0-11(a)(2) and identify the filing for which the offsetting fee was paid previously. Identify the previous filing by registration statement number, or the Form or Schedule and the date of its filing.

1. Amount Previously Paid:

2. Form, Schedule or Registration Statement No.:

3. Filing Party:

4. Date Filed:

ULTRA CLEAN HOLDINGS, INC.
26462 Corporate Avenue
Hayward, CA 94545

ADDITIONAL INFORMATION REGARDING THE ANNUAL MEETING OF STOCKHOLDERS TO BE HELD ON TUESDAY, JUNE 2, 2020

The following Notice of Change of Location relates to the proxy statement (the “Proxy Statement”) of Ultra Clean Holdings, Inc. (the “Company”), dated April 27, 2020, furnished to stockholders of the Company in connection with the solicitation of proxies by the Board of Directors of the Company for use at the Annual Meeting of Stockholders (the “Annual Meeting”) to be held on Tuesday, June 2, 2020. This Supplement is being filed with the Securities and Exchange Commission and is being made available to stockholders on or about May 15, 2020.

THE NOTICE SHOULD BE READ IN CONJUNCTION WITH THE PROXY STATEMENT.

NOTICE OF CHANGE OF LOCATION

OF ANNUAL MEETING OF STOCKHOLDERS

 TO BE HELD ON JUNE 2, 2020

To the Shareholders of Ultra Clean Holdings, Inc.:

Due to the continued public health impact of the coronavirus outbreak (COVID-19), NOTICE IS HEREBY GIVEN that the location of the Annual Meeting of Stockholders (the “Annual Meeting”) of Ultra Clean Holdings, Inc. (the “Company”) has been changed. As previously announced, the Annual Meeting will be held on Tuesday, June 2, 2020 at 12:30 p.m., Pacific Time. The Annual Meeting will be held in a virtual meeting format only. You will not be able to attend the Annual Meeting physically.

As described in the proxy materials for the Annual Meeting previously distributed, you are entitled to participate in the Annual Meeting if you were a stockholder as of the close of business on March 31, 2020, the record date, or hold a legal proxy for the meeting provided by your bank, broker, or nominee. To be admitted to the Annual Meeting at www.virtualshareholdermeeting.com/UCTT2020, you must enter the control number found on your proxy card, voting instruction form or notice you previously received. You may vote during the Annual Meeting by following the instructions available on the meeting website during the meeting. Whether or not you plan to attend the Annual Meeting, we urge you to vote and submit your proxy in advance of the meeting by one of the methods described in the proxy materials for the Annual Meeting. The proxy card included with the proxy materials previously distributed will not be updated to reflect the change in location and may continue to be used to vote your shares in connection with the Annual Meeting.

By Order of the Board of Directors,

/s/ James P. Scholhamer

James P. Scholhamer

Chief Executive Officer

May 15, 2020

The Annual Meeting on June 2, 2020 at 12:30 p.m. Pacific Time is available at

www.virtualshareholdermeeting.com/UCTT2020. The proxy statement and Annual Report are available on our Investor Relations website at http://uct.com/investors/financials-and-filings/.