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): August 29, 2016

Sagent Pharmaceuticals, Inc.

(Exact name of registrant as specified in its charter)

1901 N. Roselle Road, Suite 700

Schaumburg, Illinois 60195

(Address of principal executive offices, including zip code)

(847) 908-1600

(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:

Introduction

As previously disclosed in the Current Report on Form 8-K filed by Sagent Pharmaceuticals, Inc., a Delaware corporation (the “Company”), with the U.S. Securities and Exchange Commission (the “SEC”) on July 11, 2016, the Company entered into an Agreement and Plan of Merger, dated as of July 10, 2016 (as amended from time to time, the “Merger Agreement”), among the Company, Nichi-Iko Pharmaceutical Co., Ltd., a Japanese corporation (“Parent”) and Shepard Vision, Inc., a Delaware corporation and a wholly owned subsidiary of Parent (“Purchaser”). Pursuant to the Merger Agreement, on August 1, 2016, Purchaser commenced a tender offer to purchase all of the outstanding shares of the Company’s common stock, par value $0.01 per share (“Shares”), at a purchase price of $21.75 per Share (the “Offer Price”), net to the seller in cash, without interest, less any required withholding taxes (the “Offer”), upon the terms and subject to the conditions set forth in the Offer to Purchase (as it may be amended or supplemented from time to time), and in the related Letter of Transmittal (as it may be amended or supplemented from time to time) filed as Exhibit (a)(1)(i) and Exhibit (a)(1)(ii), respectively, to the Schedule TO originally filed with the SEC by Purchaser and Parent on August 1, 2016.

On August 29, 2016, Parent announced the completion of the Offer. The Offer expired one minute following 11:59 p.m. (12:00 a.m.), New York City time on August 26, 2016 (the “Expiration Time”). According to American Stock Transfer & Trust Company, the depositary for the Offer (the “Depositary”), as of the Expiration Time, a total of 28,229,440 Shares had been validly tendered into and not properly withdrawn from the Offer, representing approximately 85.6% of the outstanding Shares as of the Expiration Time. In addition, the Depositary advised that Notices of Guaranteed Delivery have been delivered with respect to 589,169 additional Shares, representing approximately 1.8% of the outstanding Shares as of the expiration of the Offer.

The number of Shares validly tendered (and not validly withdrawn) (excluding Shares tendered pursuant to guaranteed delivery procedures that have not yet been “received,” as defined by Section 251(h)(6) of the DGCL) pursuant to the Offer satisfied the Minimum Condition (as defined in the Merger Agreement). All conditions to the Offer having been satisfied, Purchaser accepted for payment and will promptly pay for all Shares validly tendered (and not validly withdrawn) from the Offer pursuant to the terms of the Offer.

On August 29, 2016, on the terms and subject to the conditions set forth in the Merger Agreement and in accordance with Section 251(h) of the Delaware General Corporation Law (the “DGCL”), Purchaser was merged with and into the Company (the “Merger”), with the Company continuing as the surviving corporation. Upon completion of the Merger (the “Effective Time”), the Company became a wholly-owned subsidiary of Parent. At the Effective Time, each issued and outstanding Share (other than Shares that were held by any stockholders who properly demanded appraisal for such Shares in accordance with Section 262 of the DGCL) was converted into the right to receive the Offer Price, in cash and without interest (the “Merger Consideration”) except for Shares held by the Company, Parent or Purchaser, or their respective subsidiaries, which Shares were canceled and ceased to exist, and no consideration was delivered in exchange therefor.

Each option to purchase Shares (a “Company Option”) that was outstanding and unexercised as of immediately prior to the Effective Time, was canceled as of the Effective Time (to the extent not exercised prior to the Effective Time), and the holder thereof became entitled to receive an amount in cash (without interest and less any applicable withholding taxes) equal to the product obtained by multiplying (i) the excess, if any, of the Merger Consideration over the exercise price per Share under such Company Option by (ii) the total number of Shares subject to such Company Option.

The aggregate consideration paid by Purchaser in the Offer and Merger was approximately $734,207,581.74. Parent and Purchaser used cash and available borrowing capacity under new credit facilities to consummate the Offer, the Merger, and the other transactions contemplated by the Merger Agreement, and to pay all fees and expenses in connection therewith.

The foregoing summary description of the Merger Agreement does not purport to be complete and is qualified in its entirety by reference to the full text of the Merger Agreement, a copy of which was filed as Exhibit 2.1 to the Current Report on Form 8-K filed by the Company with the SEC on July 11, 2016, and is incorporated herein by reference.

The information set forth in the Introduction of this Current Report on Form 8-K is incorporated by reference into this Item 2.01.

On August 29, 2016, in connection with the consummation of the Merger, the Company notified The NASDAQ Capital Market (“NASDAQ”) that the Merger had been consummated, and requested that the trading of Shares on NASDAQ be halted prior to market open on August 30, 2016 and that such trading be suspended and the listing of the Shares on NASDAQ be removed, in each case, prior to market open on August 30, 2016. In addition, the Company requested that NASDAQ file with the SEC an application on Form 25 to delist the Shares from NASDAQ and to deregister the Shares under Section 12(b) of the Securities Exchange Act of 1934, as amended (together with the rules and regulations promulgated thereunder, the “Exchange Act”). The Company intends to file with the SEC a Certification and Notice of Termination on Form 15 requesting the deregistration of the Shares under Section 12(g) of the Exchange Act and the suspension of the Company’s reporting obligations under Sections 13 and 15(d) of the Exchange Act.

The information disclosed in the Introduction and Item 2.01 of this Current Report on Form 8-K is incorporated by reference into this Item 3.01.

The information disclosed in the Introduction, Item 2.01, Item 3.01, Item 5.01 and Item 5.03 of this Current Report on Form 8-K is incorporated by reference to this Item 3.03.

As a result of the completion of the Offer, a change of control of the Company occurred. Upon the consummation of the Merger, the Company became a wholly-owned subsidiary of Parent.

The information disclosed in the Introduction, Item 2.01 and Item 5.02 of this Current Report on Form 8-K is incorporated by reference to this Item 5.01.

Item 5.02. Departure of Directors or Certain Officers; Election of Directors; Appointment of Certain Officers; Compensatory Arrangements of Certain Officers.

At the Effective Time the directors of Purchaser immediately prior to the Effective Time, as set forth below, became the directors of the Company until the earlier of their resignation or removal or until their respective successors are duly designated, as the case may be, and each of Robert Flanagan, Anthony Krizman, Mary Taylor Behrens, Michael Fekete and Shlomo Yanai ceased serving as directors of the Company.

At the Effective Time, (i) the Company’s Certificate of Incorporation was amended and restated in its entirety (the “Amended and Restated Certificate of Incorporation”) as set forth in Exhibit 3.1 to this Current Report on Form 8-K and (ii) the Purchaser’s by-laws, as in effect immediately prior to the Effective Time became the by-laws of the Company (the “By-laws”), except that references to the name of Purchaser were replaced by the name of the Company.

Copies of the Amended and Restated Certificate of Incorporation and the By-laws are filed as Exhibits 3.1 and 3.2, respectively, to this Current Report on Form 8-K, and are incorporated by reference to this Item 5.03.

(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.

Date: August 29, 2016