Sec Form 4 Filing - ANDERSON JAMES M @ FIRST FINANCIAL BANCORP /OH/ - 2018-04-01

FORM 4 Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934, Section 17(a) of the Public Utility Holding Company Act of 1935 or Section 30(h) of the Investment Company Act of 1940

OMB APPROVAL OMB Number: 3235-0287 Expires: November 30, 2011 Estimated average burden hours per response... 0.5

1. Name and Address of Reporting Person ANDERSON JAMES M 2. Issuer Name and Ticker or Trading Symbol FIRST FINANCIAL BANCORP /OH/ [ FFBC] 5. Relationship of Reporting Person(s) to Issuer (Check all applicable) _____ Director _____ 10% Owner X __ Officer (give title below) _____ Other (specify below) Chief Financial Officer (Last) (First) (Middle) 255 EAST 5TH STREET, SUITE 2900 3. Date of Earliest Transaction (MM/DD/YY) 04/01/2018 (Street) CINCINNATI, OH45202 4. If Amendment, Date Original Filed (MM/DD/YY) 6. Individual or Joint/Group Filing (Check Applicable Line) __ X __ Form filed by One Reporting Person _____ Form filed by More than One Reporting Person (City) (State) (Zip)

Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned 1.Title of Security (Instr. 3) 2. Transaction Date (MM/DD/YY) 2A. Deemed Execution Date, if any (MM/DD/YY) 3. Transaction Code (Instr. 8) 4. Securities Acquired (A) or Disposed of (D) (Instr. 3, 4 and 5) 5. Amount of Securities Beneficially Owned Following Reported Transaction(s) (Instr. 3 and 4) 6. Ownership Form: Direct (D) or Indirect (I) (Instr. 4) 7. Nature of Indirect Beneficial Ownership (Instr. 4) Code V Amount (A) or (D) Price Common Stock 04/01/2018 A 33,691 A 33,691 D Common Stock 04/01/2018 A 15,841 A 15,841 I By 401-K Common Stock 04/01/2018 A 405 A 405 I As UTMA Custodian for Daughter Common Stock 04/01/2018 A 592 A 592 I As UTMA Custodian for Son Common Stock 04/02/2018 A 4,680 A $ 0 4,680 I Restricted Stock Common Stock 04/02/2018 A 1,560 A $ 0 1,560 I Restricted-P

Table II - Derivative Securities Acquired, Disposed of, or Beneficially Owned ( e.g. , puts, calls, warrants, options, convertible securities) 1. Title of Derivative Security (Instr. 3) 2. Conversion or Exercise Price of Derivative Security 3. Transaction Date (MM/DD/YY) 3A. Deemed Execution Date, if any (MM/DD/YY) 4. Transaction Code (Instr. 8) 5. Number of Derivative Securities Acquired (A) or Disposed of (D) (Instr. 3, 4, and 5) 6. Date Exercisable and Expiration Date (MM/DD/YY) 7. Title and Amount of Underlying Securities (Instr. 3 and 4) 8. Price of Derivative Security (Instr. 5) 9. Number of Derivative Securities Beneficially Owned Following Reported Transaction(s) (Instr. 4) 10. Ownership Form of Derivative Security: Direct (D) or Indirect (I) (Instr. 4) 11. Nature of Indirect Beneficial Ownership (Instr. 4) Code V (A) (D) Date Exercisable Expiration Date Title Amount or Number of Shares Employee Stock Option (ISO) Right To Buy $ 9.86 04/01/2018 A 3,560 12/31/2016 04/10/2023 Common Stock 3,560 ( 2 ) 3,560 D Employee Stock Option (ISO) Right To Buy $ 11.59 04/01/2018 A 5,225 12/31/2017 02/03/2024 Common Stock 5,225 ( 3 ) 5,225 D

Reporting Owners Reporting Owner Name / Address Relationships Director 10% Owner Officer Other ANDERSON JAMES M 255 EAST 5TH STREET, SUITE 2900 CINCINNATI, OH45202 Chief Financial Officer Signatures /s/ Billie L. Meents, POA 04/03/2018 Signature of Reporting Person Date

Explanation of Responses:

( 1 )Received pursuant to the merger agreement between First Financial Bancorp. ("First Financial") and MainSource Financial Group, Inc. ("MainSource"), dated July 25, 2017 (the "Merger Agreement"), pursuant to which MainSource was merged with and into First Financial on April 1, 2018 (the "Effective Time"). Pursuant to the Merger Agreement, as of the Effective Time, (i) each issued and outstanding share of MainSource's common stock converted into the right to receive 1.3875 shares of First Financial common stock and cash in lieu of fractional shares (the "Merger Consideration"), and (ii) each outstanding restricted share and each outstanding performance share unit fully vested and was cancelled and converted automatically into the right to receive the Merger Consideration in respect of each share of MainSource's common stock underlying such award, less applicable tax withholdings. On the trading day immediately preceding Effective Date, the closing price of MainSource's common stock was $40.65 per share and the closing price of First Financial's common stock was $29.35 per share. ( 2 )Received in the Merger in exchange for an employee stock option to acquire 2566 shares of MainSource common stock for $9.86 per share ( 3 )Received in the Merger in exchange for an employee stock option to acquire 10,287 shares of MainSource common stock for $11.59 per share.

Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.

* If the form is filed by more than one reporting person, see Instruction 4(b)(v).

** Intentional misstatements or omissions of facts constitute Federal Criminal Violations. See 18 U.S.C. 1001 and 15 U.S.C. 78ff(a).

Note: File three copies of this Form, one of which must be manually signed. If space is insufficient, see Instruction 6 for procedure.
Persons who respond to the collection of information contained in this form are not required to respond unless the form displays a currently valid OMB Number.