UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM 10-K

X ANNUAL REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934

(FEE REQUIRED)

For the fiscal year ended: December 31, 2017 OR

_ TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934

(NO FEE REQUIRED)

For the transition period from _____________________________ to ______________________________

Commission File Number: 001-10607

OLD REPUBLIC INTERNATIONAL CORPORATION

(Exact name of registrant as specified in its charter)

Indicate by check mark if the registrant is a well-known seasoned issuer, as defined in Rule 405 of the Securities Act.

Yes: X/ No:

Indicate by check mark if the registrant is not required to file reports pursuant to Section 13 or Section 15(d) of the Act.

Yes: / No:X

Indicate by check mark whether the registrant (1) has filed all reports required to be filed by Section 13 or 15(d) of the Securities Exchange Act of 1934 during the preceding 12 months (or for such shorter period that the registrant was required to file such reports) and (2) has been subject to such filing requirements for the past 90 days. Yes: X/ No:

Indicate by check mark whether the registrant has submitted electronically and posted on its corporate Web site, if any, every Interactive Data File required to be submitted and posted pursuant to Rule 405 of Regulation S-T during the preceding 12 months (or for such shorter period that the registrant was required to submit and post such files). Yes: X/No:

Indicate by check mark if disclosure of delinquent filers pursuant to Item 405 of Regulation S‑K is not contained herein, and will not be contained, to the best of registrant's knowledge, in definitive proxy or information statements incorporated by reference in Part III of this Form 10-K or any amendment to this Form 10-K. o

Indicate by check mark whether the registrant is a large accelerated filer, an accelerated filer, or a non-accelerated filer, smaller reporting company, or an emerging growth company. See the definition of "large accelerated filer," "accelerated filer," "smaller reporting company," and "emerging growth company" in Rule 12b-2 of the Exchange Act.

Large accelerated filer x                             Accelerated filer o

Non-accelerated filer o (Do not check if a smaller reporting company)     Smaller reporting company o

Emerging growth company o

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. o

Indicate by check mark whether the registrant is a shell company (as defined in Exchange Act Rule 12b-2). Yes: / No:X

The aggregate fair value of the registrant's voting Common Stock held by non-affiliates of the registrant (assuming, for purposes of this calculation only, that the registrant's directors and executive officers, the registrant's various employee benefit plans and American Business & Mercantile Insurance Mutual, Inc. and its subsidiaries are all affiliates of the registrant), based on the closing sale price of the registrant's common stock on June 30, 2017 , the last day of the registrant's most recently completed second fiscal quarter, was $4,728,676,896 .

The registrant had 269,347,468 shares of Common Stock outstanding as of January 31, 2018 .

Documents incorporated by reference:

The following documents are incorporated by reference into that part of this Form 10-K designated to the right of the document title.

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There are 114 pages in this report