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): January 25, 2018

ALBIREO PHARMA, INC.

(Exact name of registrant as specified in its charter)

(857) 254-5555

Registrant’s telephone number, including area code

Not applicable

(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:

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.  ☐

On January 25, 2018, Albireo Pharma, Inc. (the “Company”) entered into an underwriting agreement (the “Underwriting Agreement”) with Cowen and Company, LLC and William Blair & Company, L.L.C., as representatives of the several underwriters named therein (collectively, the “Underwriters”), relating to the issuance and sale (the “Offering”) of 1,970,000 shares of common stock, par value $0.01 per share, of the Company. The price to the public in the Offering is $33.00 per share, and the Underwriters have agreed to purchase the shares from the Company pursuant to the Underwriting Agreement at a price of $31.02 per share. The net proceeds to the Company from the Offering are expected to be approximately $60.8 million after deducting underwriting discounts and commissions and other estimated offering expenses. Under the terms of the Underwriting Agreement, the Underwriters have an option, exercisable for 30 days, to purchase up to an additional 295,500 shares of the Company’s common stock at the public offering price less the underwriting discounts and commissions. All of the shares in the Offering are being sold by the Company. The Offering is expected to close on or about January 29, 2018, subject to satisfaction of customary closing conditions.

The shares will be issued pursuant to the Company’s shelf registration statement on Form S-3 (File No. 333- 220958) filed with the Securities and Exchange Commission (the “Commission”) on October 13, 2017, amended on November 16, 2017 and declared effective by the Commission on December 5, 2017 (the “Registration Statement”). A prospectus and prospectus supplement relating to the Offering have been filed with the Commission.

The Underwriting Agreement contains customary representations, warranties and agreements by the Company, customary conditions to closing, indemnification obligations of the Company and the Underwriters, including for liabilities arising 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 the 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 terms of the Underwriting Agreement is qualified in its entirety by reference to the Underwriting Agreement, which is attached as Exhibit 1.1 hereto and incorporated by reference herein. A copy of the legal opinion of Mintz, Levin, Cohn, Ferris, Glovsky and Popeo, P.C. relating to the validity of the issuance and sale of the shares in the Offering is attached as Exhibit 5.1 hereto.

On January 25, 2018, the Company issued a press release announcing the pricing of the Offering, a copy of which is attached hereto as Exhibit 99.1 and incorporated herein by reference.

(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.