UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, DC 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)

February 15, 2018

Pacific Biosciences of California, Inc.

(Exact name of registrant as specified in its charter)

1305 O’Brien Drive

Menlo Park, California 94025

(Address of principal executive offices, including zip code)

(650) 521-8000

(Registrant’s telephone number, including area code)

(Former name or former address, if changed since last report)

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 (see General Instruction A.2):

Indicate by check mark whether the registrant is an emerging growth company as defined in Rule 405 of the Securities Act of 1933 (§230.405 of this chapter) or Rule 12b-2 of the Securities Exchange Act of 1934 (§240.12b-2 of this chapter).

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.  ☐

Pursuant to that certain underwriting agreement dated February 13, 2018 (the “Underwriting Agreement”), by and between Pacific Biosciences of California, Inc. (the “Company”) and Cantor Fitzgerald & Co., as representative of the several underwriters named in Schedule A thereto (the “Underwriters”) relating to the public offering (the “Offering”) of 12,500,000 shares of the Company’s common stock, $0.001 par value per share (the “Common Stock”), at a price to the public of $2.40 per share, the Company granted the Underwriters a 30-day option to purchase up to an additional 1,875,000 shares of Common Stock (the “Option Shares”). The Underwriters notified the Company of the exercise in full of their option to purchase the additional shares on February 15, 2018, and the sale of shares of Common Stock subject to such option, closed on February 20, 2018. The net proceeds to the Company from the sale of the Option Shares, after deducting the underwriting discount and estimated offering expenses payable by the Company, are expected to be approximately $4.3 million.

The shares of Common Stock are being offered and sold pursuant to the Company’s shelf registration statement on Form S-3 (File No. 333-219642) (the “Registration Statement”), which was declared effective by the Securities and Exchange Commission (the “SEC”) on August 18, 2017, as supplemented by a preliminary prospectus supplement, dated February 12, 2018, and a final prospectus supplement, dated February 13, 2018, filed with the SEC pursuant to Rule 424(b) under the Securities Act of 1933, as amended.

In connection with the sale of the Option Shares, the legal opinion as to the legality of the Common Stock sold is being filed as Exhibit 5.1 to this Current Report on Form 8-K and is incorporated herein and into the Registration Statement by reference.

(d) Exhibits.

SIGNATURE

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.

Date: February 20, 2018