Pdf Solutions Inc — Current Report (Form 8-K)

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM 8-K

CURRENT REPORT

Pursuant to Section 13 or 15(d)

of the Securities Exchange Act of 1934

Date of Report (Date of Earliest Event Reported): May 13, 2026

PDF SOLUTIONS, INC.

(Exact name of registrant as specified in its charter)

000-31311

(Commission File Number)

2858 De La Cruz Boulevard

Santa Clara, CA 95050

(Address of principal executive offices, with zip code)

(408) 280-7900

(Registrant’s telephone number, including area code)

Check the appropriate box below if the Form 8-K filing is intended to simultaneously satisfy the filing obligation of the registrant under any of the following provisions:

Securities registered pursuant to Section 12(b) of the Exchange Act:

Indicate by check mark whether the registrant is an emerging growth company as defined in Rule 405 of the Securities Act of 1933 or Rule 12b-2 of the Securities Exchange Act of 1934.

Emerging growth company ☐

If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act. ☐

On May 13, 2026, PDF Solutions, Inc. (the “Company”) entered into an underwriting agreement (the “Underwriting Agreement”) with Morgan Stanley & Co. LLC, as representative of the several underwriters named therein (collectively, the “Underwriters”), and Advantest America, Inc. (the “Selling Stockholder”) in connection with (i) the offering, issuance and sale by the Company of 1,946,630 shares of the Company’s common stock, $0.00015 par value per share (the “Common Stock”), including 685,246 shares sold pursuant to the Underwriters’ full exercise of their option to purchase additional shares, and (ii) the offering and sale by the Selling Stockholder of 3,306,924 shares of the Company’s Common Stock, at an offering price of $44.00 per share, less underwriting discounts and commissions (collectively, the “Offering”). The Offering closed on May 15, 2026.

The Offering was made pursuant to an effective shelf registration statement on Form S-3 (Registration No. 333-295834), including a base prospectus and a related prospectus supplement filed with the Securities and Exchange Commission. The gross proceeds to the Company from the sale of shares of Common Stock by the Company, before deducting underwriting discounts and commissions and estimated offering expenses, were approximately $85.7 million. The Company did not receive any proceeds from the sale of shares by the Selling Stockholder.

The Underwriting Agreement contains customary representations, warranties, covenants and agreements by the Company, customary conditions to closing, indemnification obligations of the Company and the Underwriters, including for liabilities under the Securities Act of 1933, as amended, other obligations of the parties and termination provisions. The representations, warranties and covenants contained in the Underwriting Agreement were made only for purposes of such agreement and as of specific dates, were solely for the benefit of the parties to such agreement, and may be subject to limitations agreed upon by the contracting parties.

The foregoing description of the Underwriting Agreement is not complete and is qualified in its entirety by reference to the full text of the Underwriting Agreement, a copy of which is filed as Exhibit 1.1 to this Current Report on Form 8-K and is incorporated by reference herein.

Latham & Watkins LLP, counsel to the Company, has issued an opinion regarding the validity of the shares of Common Stock offered and sold in the Offering. A copy of the opinion is filed as Exhibit 5.1 to this Current Report on Form 8-K.

(d) Exhibits.

SIGNATURES

Pursuant to the requirements of the Securities Exchange Act of 1934, the Registrant has duly caused this report to be signed on its behalf by the undersigned hereunto duly authorized.

Dated: May 15, 2026