Fifth Third Bancorp : Prospectus filed under Rule 424(b)(3)

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FORM 424B3

FIFTH THIRD BANCORP - FITB

Filed: January 23, 2019 (period: )

Prospectus filed under Rule 424(b)(3)

The information contained herein may not be copied, adapted or distributed and is not warranted to be accurate, complete or timely. The user assumes all risks for any damages or losses arising from any use of this information, except to the extent such damages or losses cannot be limited or excluded by applicable law. Past financial performance is no guarantee of future results.

Table of Contents

Filed Pursuant to Rule 424(b)(3)

Registration No. 333-210429

This prospectus supplement relates to an effective registration statement, but the information in this prospectus supplement is not complete and may be changed. This prospectus supplement and the accompanying prospectus is not an offer to sell these securities, and we are not soliciting an offer to buy these securities in any jurisdiction where the offer or sale is not permitted.

Subject to completion, dated January 23, 2019

Prospectus supplement

(To prospectus dated March 28, 2016)

$ % Senior Notes due 2024

Interest payableand

Issue price:

Fifth Third Bancorp is offering $

aggregate principal amount of

% Senior Notes due 2024 (the "notes").

We will pay interest on the notes semi-annually in arrears onandof each year, beginning

, 2019.

The notes will mature on , 2024. The notes will be unsecured senior obligations of Fifth Third Bancorp. The notes are not subject to repayment at the option of the holders at any time prior to maturity. We may redeem the notes, in whole or in part, on or after the date that is 30 days prior to the maturity date at a redemption price equal to 100% of the principal amount of the notes to be redeemed plus accrued and unpaid interest to, but excluding, the redemption date. There will be no sinking fund for the notes. The notes will be issued only in minimum denominations of $2,000 or any integral multiples of $1,000 in excess thereof.

See "Risk factors" beginning on page S-5 of this prospectus supplement and in the documents incorporated by reference in this prospectus supplement for a discussion of certain risks that you should consider in connection with an investment in the notes.

Neither the Securities and Exchange Commission nor any state securities commission has approved or disapproved of the notes or determined that this prospectus supplement or the accompanying prospectus is accurate or complete. Any representation to the contrary is a criminal offense.

Underwriting
Price to public	Discount	Proceeds to us
Per Note	%	%	%
Total	$	$	$

The price to the public set forth above does not include accrued interest, if any. Interest on the notes will accrue from

, 2019.

The notes are not savings accounts, deposits or other obligations of any of our bank or non-bank subsidiaries and are not insured or guaranteed by the Federal Deposit Insurance Corporation or any other governmental agency.

The notes will not be listed on any securities exchange or interdealer market quotation system. Currently, there is no public market for the notes.

We expect that the notes will be ready for delivery through the book-entry facilities of The Depository Trust Company, Clearstream Banking, Société

Anonyme or Euroclear Bank S.A./N.V., as operator of the Euroclear System, as applicable, against payment in New York, New York on or about 2019.

,

Joint Book-Running Managers

Morgan Stanley

Fifth Third Securities

Goldman Sachs & Co. LLC

RBC Capital Markets

The date of this prospectus supplement is January

, 2019.

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Table of Contents
Prospectus supplement	Page
About this prospectus supplement	S-ii
Where you can find more information	S-iii
Forward-looking statements	S-iv
Summary	S-1
Risk factors	S-5
Use of proceeds	S-7
Regulatory considerations	S-8
Description of the notes	S-11
Book-entry, delivery and form	S-18
Certain U.S. federal income tax consequences to non-U.S. holders of notes	S-21
ERISA Considerations	S-24
Underwriting (conflicts of interest)	S-26
Validity of the notes	S-31
Experts	S-32
Prospectus	Page
About this prospectus	2
Where you can find more information	2
Use of proceeds	3
Plan of distribution	3
Validity of securities	5
Experts	5
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Table of Contents

S-i

About this prospectus supplement

This document consists of two parts. The first part is the prospectus supplement, which describes the specific terms of this offering and certain other matters and also adds to and updates information contained in the accompanying prospectus. The second part, the accompanying prospectus, gives more general information about securities we may offer from time to time, some of which may not apply to this offering. You should read both this prospectus supplement and the accompanying prospectus, together with additional information described under the heading "Where you can find more information" in this prospectus supplement.

Unless otherwise mentioned or unless the context requires otherwise, all references in this prospectus supplement to "Fifth Third," "the Company," "we," "us," "our" or similar references mean Fifth Third Bancorp and its subsidiaries.

If the information set forth in this prospectus supplement differs in any way from the information set forth in the accompanying prospectus, you should rely on the information set forth in this prospectus supplement.

You should not assume that the information appearing in this prospectus supplement, the accompanying prospectus or any document incorporated by reference is accurate as of any date other than the date of the applicable document. Our business, financial condition, results of operations and prospects may have changed since that date.

We have not, and the underwriters have not, authorized anyone to provide any information other than that contained or incorporated by reference in this prospectus supplement or in any free writing prospectus prepared by or on behalf of us or to which we have referred you. We and the underwriters take no responsibility for, and can provide no assurance as to the reliability of, any other information that others may give you.

This prospectus supplement may be used only for the purpose for which it has been prepared. We are not, and the underwriters are not, making an offer to sell these securities in any jurisdiction where the offer or sale is not permitted. Neither this prospectus supplement nor the accompanying prospectus constitutes an offer of, or an invitation on our behalf or on behalf of the underwriters to subscribe for and purchase, any securities, and may not be used for or in connection with an offer or solicitation by anyone, in any jurisdiction in which such an offer or solicitation is not authorized or to any person to whom it is unlawful to make such an offer or solicitation.

PRIIPs Regulation / Prospectus Directive / Prohibition of Sales to EEA Retail Investors

The notes are not intended to be offered, sold or otherwise made available to and should not be offered, sold or otherwise made available to any retail investor in the EEA. For these purposes, a retail investor means a person who is one (or more) of: (i) a retail client as defined in point (11) of Article 4(1) of MiFID II; or (ii) a customer within the meaning of Directive 2002/92/EC (as amended, the "Insurance Mediation Directive"), where that customer would not qualify as a professional client as defined in point (10 ) of Article 4(1) of MIFID II; or (iii) not a qualified investor as defined in Directive 2003/71/EC (as amended, the "Prospectus Directive").

Consequently no key information document required by Regulation (EU) No 1286/2014 (as amended, the "PRIIPs Regulation") for offering or selling the notes or otherwise making them available to retail investors in the EEA has been prepared and therefore offering or selling the notes or otherwise making them available to any retail investor in the EEA may be unlawful under the PRIIPs Regulation.

This prospectus supplement is not a prospectus for the purposes of the Prospectus Directive as implemented in member states of the EEA.

S-ii

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Where you can find more information

We file annual, quarterly and current reports, proxy statements and other information with the Securities and Exchange Commission (the "SEC"). Our SEC filings are available to the public over the Internet at the SEC web site athttp://www.sec.gov.

The SEC allows us to "incorporate by reference" into this prospectus supplement the information we file with it, which means that we can disclose important information to you by referring you to those documents. The information incorporated by reference is an important part of this prospectus supplement and information that we subsequently file with the SEC will automatically update and supersede information in this prospectus supplement, and in our other filings with the SEC. In other words, in case of a conflict or inconsistency between information contained in this prospectus supplement and information incorporated by reference into this prospectus supplement, you should rely on the information that was filed later.

We incorporate by reference the documents listed below, which we have already filed with the SEC, and any documents we file with the SEC in the future under Section 13(a), 13(c), 14 or 15(d) of the Securities Exchange Act of 1934, as amended (other than information in such future filings deemed not to have been filed), until this offering is completed or terminated:

• • Annual Report on Form 10-K for the fiscal year ended December 31, 2017 filed on February 28, 2018;

• • Quarterly Reports on Form 10-Q for the quarters ended March 31, 2018, June 30, 2018 and September 30, 2018 filed on May 4, 2018, on August 8, 2018, and on November 6, 2018 respectively;

• • Current Reports on Form 8-K filed on February 2, 2018, February 9, 2018, February 27, 2018, March 14, 2018 (as amended on March 14, 2018), March 16, 2018, March 27, 2018, April 19, 2018 (as amended on June 22, 2018), May 21, 2018, May 22, 2018, May 24, 2018, June 5, 2018, June 8, 2018, June 15, 2018, June 27, 2018, June 29, 2018, July 23, 2018, September 24, 2018, December 28, 2018 and January 23, 2019; and

• • Proxy Statement on Schedule 14A dated March 6, 2018.

Effective January 1, 2018, Fifth Third adopted ASU 2016-01-Financial Instruments-Overall (Subtopic 825-10): Recognition and Measurement of Financial Assets and Financial Liabilities. The adoption, which was applied retrospectively, did not have a material impact on the Consolidated Financial Statements. However, equity securities affected by the guidance, which were previously classified as trading or available-for-sale, have been reclassified in the Consolidated Balance Sheets as equity securities. Fifth Third provided disclosure of this change within Note 3 to the Condensed Consolidated Financial Statements and other qualitative information reported within the quarterly report on Form 10-Q for the quarter ended September 30, 2018.

You can obtain a copy of these Fifth Third filings at no cost on Fifth Third's website,http://www.53.comunder the "Investor Relations" link, then under the heading "Financial Information" and then under the subheading "SEC Filings". The information contained on our website is not incorporated into this prospectus supplement or accompanying prospectus except as described in this section of this prospectus supplement. You also may request a copy of these filings (other than an exhibit to a filing unless that exhibit is specifically incorporated by reference into that filing) at no cost, by writing or calling us at the following address:

Office of the Corporate Secretary

Fifth Third Bancorp

Fifth Third Center

38 Fountain Square Plaza

MD10909F Cincinnati, OH 45263

[phone]

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