Description of Securities Registered Under Section 12 of the Exchange Act

Exhibit 4.2

DESCRIPTION OF THE REGISTRANT’S SECURITIES

REGISTERED PURSUANT TO SECTION 12 OF THE SECURITIES

EXCHANGE ACT OF 1934

The following summary of the terms of our capital stock is not meant to be complete and is qualified by reference to the relevant provisions of the Delaware General Corporation Law (the “DGCL”) and our amended and restated certificate of incorporation (our “certificate of incorporation”) and our amended and restated bylaws (our “bylaws”). We have summarized certain portions of the Certificate of Incorporation and Bylaws below. This information does not purport to be complete and is subject in all respects to the applicable provisions of our certificate of incorporation and bylaws, which are incorporated by reference herein.

Authorized Capital Stock

Our Certificate of Incorporation authorizes us to issue 90,000,000 shares of common stock, par value $0.001 per share, and 10,000,000 shares of preferred stock, par value $0.001 per share.

Common Stock

As of December 27, 2019, there were 39,881,505 shares of common stock outstanding and three stockholders of record. The holders of common stock are entitled to one vote per share on all matters to be voted upon by the stockholders. Subject to preferences that may be applicable to any outstanding preferred stock, the holders of common stock are entitled to receive ratably such dividends, if any, as may be declared from time to time by our board of directors out of funds legally available therefor. In the event of the liquidation, dissolution or winding up of Ultra Clean, the holders of common stock are entitled to share ratably in all assets remaining after payment of liabilities, subject to prior distribution rights of preferred stock, if any, then outstanding. The common stock has no preemptive or conversion rights or other subscription rights. There are no redemption or sinking fund provisions applicable to the common stock. All outstanding shares of common stock are fully paid and non-assessable.

Preferred Stock

Our board of directors is authorized, subject to any limitations imposed by law, without stockholder approval, from time to time to issue up to 10,000,000 shares of preferred stock in one or more series, each series to have rights and preferences, including voting rights, dividend rights, conversion rights, redemption privileges and liquidation preferences, as our board of directors may determine. The issuance of preferred stock, while providing desirable flexibility in connection with possible acquisitions and other corporate purposes, could have the effect of making it more difficult for a third party to acquire, or of discouraging a third party from attempting to acquire, a majority of our voting stock outstanding. We have no shares of preferred stock outstanding, and we have no present plans to issue any shares of preferred stock.

Certain Provisions of Our Certificate of Incorporation and Bylaws

Our Bylaws vest the power to call special meetings of stockholders in our chairman of the board and our board of directors. Stockholders are permitted under our Certificate of Incorporation to act by written consent in lieu of a meeting.

To be properly brought before an annual meeting of stockholders, any stockholder proposal or nomination for the board of directors must be delivered to our secretary not less than 90 days nor more than 120 days prior to the first anniversary of the prior year’s annual meeting; provided, however, that in the event that the date of the annual meeting is advanced more than 30 days prior to such anniversary date or delayed more than 70 days after such anniversary date, then to be timely such notice must be received by us no earlier than 120 days prior to such annual meeting and no later than the later of 70 days prior to the day of the meeting or the 10th day following the day on which public announcement of the date of the meeting was first made by us. Such notice must contain information specified in the Bylaws as to the director

nominee or proposal of other business, information about the stockholder making the nomination or proposal and the beneficial owner, if any, on behalf of whom the nomination or proposal is made, including name and address, class and number of shares owned, and representations regarding the intention to make such a proposal or nomination and to solicit proxies in support of it.

Certain Anti-Takeover Effects of Delaware Law

We are subject to Section 203 of the Delaware General Corporation Law (“Section 203”). In general, Section 203 prohibits a publicly held Delaware corporation from engaging in various “business combination” transactions with any interested stockholder for a period of three years following the date of the transactions in which the person became an interested stockholder, unless:

A “business combination” is defined to include mergers, asset sales, and other transactions resulting in financial benefit to a stockholder. In general, an “interested stockholder” is a person who, together with affiliates and associates, owns (or within three years, did own) 15% or more of a corporation’s voting stock.

The statute could prohibit or delay mergers or other takeover or change in control attempts with respect to us and, accordingly, may discourage attempts to acquire us even though such a transaction may offer our stockholders the opportunity to sell their stock at a price above the prevailing market price.

Listing

Our common stock is listed on the NASDAQ Global Select Market under the symbol “UCTT.”

Transfer Agent and Registrar

The transfer agent and registrar for the shares of our common stock is Equiniti Trust Company.

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