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): June 20, 2014

ABBVIE INC.

(Exact name of registrant as specified in its charter)

1 North Waukegan Road

North Chicago, Illinois 60064-6400

(Address of principal executive offices) (Zip Code)

Registrant’s telephone number, including area code:  (847) 932-7900

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:

x               Written communications pursuant to Rule 425 under the Securities Act (17 CFR 230.425)

o                 Soliciting material pursuant to Rule 14a-12 under the Exchange Act (17 CFR 240.14a-12)

o                 Pre-commencement communications pursuant to Rule 14d-2(b) under the Exchange Act (17 CFR 240.14d-2(b))

o                 Pre-commencement communications pursuant to Rule 13e-4(c) under the Exchange Act (17 CFR 240.13e-4(c))

Item 8.01. Other Events.

On June 20, 2014, AbbVie Inc. (“AbbVie”) issued an announcement (the “Announcement”) pursuant to the U.K. City Code on Takeovers and Mergers confirming that it made an indicative approach to Shire plc (“Shire”) with a merger proposal which was rejected by the Board of Shire. A copy of the Announcement is attached hereto as Exhibit 99.1 and is incorporated by reference into this Item 8.01.

Item 9.01. Financial Statements and Exhibits.

2

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.

3

EXHIBIT INDEX

4

Exhibit 99.1

NOT FOR RELEASE, PUBLICATION OR DISTRIBUTION, IN WHOLE OR IN PART, DIRECTLY OR INDIRECTLY, IN, INTO OR FROM ANY JURISDICTION WHERE TO DO SO WOULD CONSTITUTE A VIOLATION OF THE RELEVANT LAWS OR REGULATIONS OF SUCH JURISDICTION

THIS IS AN ANNOUNCEMENT FALLING UNDER RULE 2.4 OF THE CITY CODE ON TAKEOVERS AND MERGERS (THE “CODE”) AND DOES NOT CONSTITUTE AN ANNOUNCEMENT OF A FIRM INTENTION TO MAKE AN OFFER UNDER RULE 2.7 OF THE CODE. THERE CAN BE NO CERTAINTY THAT ANY FIRM OFFER WILL BE MADE

Response to Press Speculation

London, June 20, 2014: AbbVie Inc. (“AbbVie”) notes the recent press speculation and confirms it made an indicative approach to Shire plc (“Shire”) with a merger proposal which was rejected by the Board of Shire. There can be no certainty that any firm offer will be made. Discussions are no longer ongoing.

AbbVie’s initial cash and share proposal in early May 2014 represented an indicative offer of £39.50 for each Shire share.(1) AbbVie’s third and latest cash and share proposal when made represented an indicative offer of £46.26 for each Shire share.(2)

In accordance with Rule 2.6(a) of the Code, AbbVie must, by not later than 5.00 p.m. on July 18, 2014, either announce a firm intention to make an offer for Shire in accordance with Rule 2.7 of the Code or announce that it does not intend to make an offer, in which case the announcement will be treated as a statement to which Rule 2.8 of the Code applies. This deadline will only be extended with the consent of the Takeover Panel in accordance with Rule 2.6(c) of the Code.

In accordance with Rule 2.10 of the Code, AbbVie confirms that as of June 18, 2014, it had in issue 1,591,512,411 common shares of US$0.01 par value each (excluding common shares held in treasury). The International Securities Identification Number (ISIN) of the common shares is US00287Y1091.

AbbVie reserves the right to introduce other forms of consideration and/or vary the mix of consideration. AbbVie also reserves the right to make an offer at any time for less than the equivalent of £46.26 for each Shire share:

(1)  Based on AbbVie’s closing share price of $51.18 (an exchange rate of $1.00:£0.5920) on May 2, 2014.

(2)  Based on AbbVie’s closing share price of $54.03 (an exchange rate of $1.00:£0.5982) on May 29, 2014.

1

In accordance with Rule 30.4 of the Code, a copy of this announcement will be available on AbbVie’s website at www.abbvieinvestor.com.

A further announcement will be made as appropriate.

Enquiries:

AbbVie investor contacts

Larry Peepo (Tel: +1 847 935 6722)

Liz Shea (Tel: +1 847 935 2211)

AbbVie media contacts

Jennifer Smoter (Tel: +1 847 935 8865)

Adelle Infante (Tel: +1 847 938 8745)

J.P. Morgan (Financial Adviser)

Jeffrey Hoffman / Henry Gosebruch (New York, Tel: +1 212 270 6000)

Dwayne Lysaght / James Robinson (London, Tel: +44 207 742 4000)

About AbbVie

AbbVie is a global, research-based biopharmaceutical company formed in January 2013 following separation from Abbott Laboratories. The company’s mission is to use its expertise, dedicated people and approach to innovation to develop and market advanced therapies that address some of the world’s most complex and serious diseases. AbbVie employs approximately 25,000 people worldwide and markets medicines in more than 170 countries. AbbVie is traded on the New York Stock Exchange under “ABBV”. Additional information is available on the company’s website at www.abbvieinvestor.com.

J.P. Morgan Securities LLC (“J.P. Morgan”), together with its affiliate J.P. Morgan Limited (which conducts its U.K. investment banking business as J.P. Morgan Cazenove and which is authorised and regulated by the Financial Conduct Authority in the United Kingdom), is acting exclusively for AbbVie in connection with the possible offer and for no one else, and is not, and will not be, responsible to anyone other than AbbVie for providing the protections afforded to clients of J.P. Morgan or its affiliates, or for providing advice in relation to the possible offer or any other matters referred to in this announcement.

Disclosure requirements of the Code

Under Rule 8.3(a) of the Code, any person who is interested in 1% or more of any class of relevant securities of an offeree company or of any securities exchange offeror (being any offeror other than an offeror in respect of which it has been announced that its offer is, or is likely to be, solely in cash) must make an Opening Position Disclosure following the commencement of the offer period and, if later, following the announcement in which any securities exchange offeror is first identified. An Opening Position Disclosure must contain details of the person’s interests and short positions in, and rights to subscribe for, any relevant securities of each of (i) the offeree company and (ii) any securities exchange offeror(s). An Opening Position Disclosure by a person to whom Rule 8.3(a) applies must be made by no later than 3.30 pm (London time) on the 10th business day following the commencement of the offer period and, if appropriate, by no later than 3.30 pm (London time) on the 10th business day following the announcement in which any

2

securities exchange offeror is first identified. Relevant persons who deal in the relevant securities of the offeree company or of a securities exchange offeror prior to the deadline for making an Opening Position Disclosure must instead make a Dealing Disclosure.

Under Rule 8.3(b) of the Code, any person who is, or becomes, interested in 1% or more of any class of relevant securities of the offeree company or of any securities exchange offeror must make a Dealing Disclosure if the person deals in any relevant securities of the offeree company or of any securities exchange offeror. A Dealing Disclosure must contain details of the dealing concerned and of the person’s interests and short positions in, and rights to subscribe for, any relevant securities of each of (i) the offeree company and (ii) any securities exchange offeror, save to the extent that these details have previously been disclosed under Rule 8. A Dealing Disclosure by a person to whom Rule 8.3(b) applies must be made by no later than 3.30 pm (London time) on the business day following the date of the relevant dealing.

Disclosures are therefore required in the shares of AbbVie and Shire.

If two or more persons act together pursuant to an agreement or understanding, whether formal or informal, to acquire or control an interest in relevant securities of an offeree company or a securities exchange offeror, they will be deemed to be a single person for the purpose of Rule 8.3.

Opening Position Disclosures must also be made by the offeree company and by any offeror and Dealing Disclosures must also be made by the offeree company, by any offeror and by any persons acting in concert with any of them (see Rules 8.1, 8.2 and 8.4).

Details of the offeree and offeror companies in respect of whose relevant securities Opening Position Disclosures and Dealing Disclosures must be made can be found in the Disclosure Table on the Takeover Panel’s website at www.thetakeoverpanel.org.uk, including details of the number of relevant securities in issue, when the offer period commenced and when any offeror was first identified. You should contact the Takeover Panel’s Market Surveillance Unit on +44 (0)20 7638 0129 if you are in any doubt as to whether you are required to make an Opening Position Disclosure or a Dealing Disclosure.

Forward-Looking Statements

This announcement contains certain forward-looking statements with respect to a possible combination involving AbbVie and Shire. The words “believe,” “expect,” “anticipate,” “project” and similar expressions, among others, generally identify forward-looking statements. AbbVie cautions that these forward-looking statements are subject to risks and uncertainties that may cause actual results to differ materially from those indicated in the forward-looking statements. Such risks and uncertainties include, but are not limited to, the possibility that a possible combination will not be pursued, failure to obtain necessary regulatory approvals or required financing or to satisfy any of the other conditions to the possible combination if it is made, adverse effects on the market price of AbbVie’s common stock and on AbbVie’s operating results because of a failure to complete the possible combination, failure to realise the expected benefits of the possible combination, negative effects relating to the announcement of the possible combination or any further announcements relating to the possible combination or the consummation of the possible combination on the market price of AbbVie’s common stock, significant transaction costs and/or unknown liabilities, general economic and business conditions that affect the combined companies following the consummation of the possible combination,

3

changes in global, political, economic, business, competitive, market and regulatory forces, future exchange and interest rates, changes in tax laws, regulations, rates and policies, future business combinations or disposals and competitive developments. These forward-looking statements are based on numerous assumptions and assessments made by AbbVie in light of its experience and perception of historical trends, current conditions, business strategies, operating environment, future developments and other factors it believes appropriate. By their nature, forward-looking statements involve known and unknown risks and uncertainties because they relate to events and depend on circumstances that will occur in the future. The factors described in the context of such forward-looking statements in this announcement could cause AbbVie’s plans with respect to Shire, actual results, performance or achievements, industry results and developments to differ materially from those expressed in or implied by such forward-looking statements. Although it is believed that the expectations reflected in such forward-looking statements are reasonable, no assurance can be given that such expectations will prove to have been correct and persons reading this announcement are therefore cautioned not to place undue reliance on these forward-looking statements which speak only as at the date of this announcement. Additional information about economic, competitive, governmental, technological and other factors that may affect AbbVie is set forth in Item 1A, “Risk Factors,” in AbbVie’s 2013 Annual Report on Form 10-K, which has been filed with United States Securities and Exchange Commission (the “SEC”), the contents of which are not incorporated by reference into, nor do they form part of, this announcement. AbbVie undertakes no obligation to release publicly any revisions to forward-looking statements as a result of subsequent events or developments, except as required by law.

Additional Information

This document is provided for informational purposes only and does not constitute an offer to sell, or an invitation to subscribe for or purchase or purchase or exchange, any securities or the solicitation of any vote or approval in any jurisdiction, nor shall there be any sale, issuance, exchange or transfer of the securities referred to in this document in any jurisdiction in contravention of applicable law. Subject to future developments, AbbVie may file a registration statement and/or tender offer documents with the SEC in connection with a combination. Holders of Shire and/or AbbVie shares should read those filings, and any other filings made by AbbVie with the SEC in connection with the combination, as they will contain important information. Those documents, if and when filed, as well as AbbVie’s other public filings with the SEC may be obtained without charge at the SEC’s website at www.sec.gov and at AbbVie’s website at www.abbvieinvestor.com.

This announcement has been prepared in accordance with English law and the Code and information disclosed may not be the same as that which would have been prepared in accordance with the laws of jurisdictions outside England.

Ends

4