Comerica Incorporated : Form of prospectus disclosing information, facts, events covered in both forms 424B2, 424B3

Table of Contents

Filed Pursuant to Rule 424(b)(5)

Registration No. 333-223083

The information in this preliminary prospectus supplement is not complete and may be changed. This preliminary prospectus supplement and the accompanying prospectus are 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, preliminary prospectus supplement dated January 28, 2019

Prospectus supplement

(To Prospectus dated February 16, 2018)

$

Comerica Incorporated

% Senior Notes due

We are offering $ aggregate principal amount of our

% senior notes due (the "notes"). We will pay interest on the noteson and of each year, beginning on , 2019. The notes will mature on , . The notes are redeemable, in whole or in part, at any time on and after , at 100% of the principal amount of the notes to be redeemed, plus accrued and unpaid interest to, but not including, the redemption date. See "Description of the Notes-Optional Redemption."

The notes will be our unsecured and unsubordinated obligations and will rank equally among themselves and with all of our other unsecured and unsubordinated indebtedness from time to time outstanding. The notes will not be guaranteed by any of our subsidiaries.

The notes will be issued only in registered book-entry form, in minimum denominations of $2,000 and integral multiples of $1,000 in excess thereof.

The notes are not deposits or other obligations of a bank or savings association and are not insured or guaranteed by the Federal Deposit Insurance Corporation or any other governmental agency.

Investing in the notes involves risks. See "Risk Factors" beginning on page S-9 to read about factors you should consider before buying the notes.

Neither the Securities and Exchange Commission nor any other regulatory body has approved or disapproved of these securities or determined if this prospectus supplement or the accompanying prospectus is truthful or complete. Any representation to the contrary is a criminal offense.

Per note

Total

Public offering price(1)	%	$
Underwriting discount	%	$
Proceeds to Comerica (before expenses)(1)	%	$

(1)Plus accrued and unpaid interest, if any, from

, 2019 to the date of delivery.

The underwriters expect to deliver the notes in book-entry form only through the facilities of The Depository Trust Company and its participants, including Clearstream Banking, S.A., and Euroclear Bank SA/NV, on or about , 2019, against payment in immediately available funds.

Joint Book-Running Managers

Morgan Stanley

J.P. Morgan

Co-Managers

Comerica Securities

Sandler O'Neill + Partners, L.P.

The date of this prospectus supplement is

, 2019

You should rely only on the information contained or incorporated by reference in this prospectus supplement, the accompanying prospectus or any free writing prospectus we have authorized. We have not, and the underwriters have not, authorized anyone to provide you with information that is different. We are not, and the underwriters are not, making an offer to sell these securities in any jurisdiction where the offer or sale of these securities is not permitted. This prospectus supplement and the accompanying prospectus may only be used where it is legal to sell these securities. You should assume that the information in this prospectus supplement, the accompanying prospectus and any information we have incorporated herein and therein by reference is accurate only as of their respective dates. Our business, financial condition, results of operations and prospects may have changed since those respective dates.

Table of Contents

Page

Prospectus Supplement
About this Prospectus Supplement	S-ii
Where You Can Find More Information	S-ii
Cautionary Statement Regarding Forward-Looking Statements	S-iv
Summary	S-1
Risk Factors	S-9
Use of Proceeds	S-12
Capitalization	S-13
Description of the Notes	S-14
Certain United States Federal Income Tax Consequences	S-20
Certain ERISA Considerations	S-24
Underwriting (Conflicts of interest)	S-26
Legal Matters	S-31
Experts	S-31

Prospectus

Page

About this Prospectus 3

Forward-Looking Statements 3

Comerica Incorporated 4

Risk Factors 4

Use of Proceeds 5

Consolidated Ratio of Earnings to Fixed Charges 5

Description of Capital Stock 5

Description of Depositary Shares 9

Description of Debt Securities 12 Description of the Warrants to Purchase

Common stock or Preferred Stock 19

Description of the Warrants to Purchase Debt Securities 21 Description of Stock Purchase Contracts and Stock Purchase

Units 22

Plan of Distribution 22

ERISA Considerations 24

Legal Matters 26

Experts 26

Where You Can Find More Information 26

S-i

About this Prospectus Supplement

This document consists of two parts. The first part is this prospectus supplement, which describes the specific terms of this offering of the notes. The second part is the accompanying prospectus, which describes more general information, some of which may not apply to this offering. You should read both this prospectus supplement and the accompanying prospectus, together with the additional information described under the heading "Where You Can Find More Information" below.

All references in this prospectus supplement to "Comerica," "we," "us," "our" or similar references mean Comerica Incorporated and its successors, but does not include our consolidated subsidiaries except where the context otherwise so requires.

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. If the information conflicts with any statement in a document which we have incorporated by reference, then you should only consider the statement in the more recent document.

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's website athttp://www.sec.govand on the investor relations page of our website athttp://www.comerica.com. Except for those SEC filings incorporated by reference in this prospectus supplement, none of the other information on our website is part of this prospectus supplement.

The SEC's rules allow us to "incorporate by reference" information into this prospectus supplement. This means that we can disclose important information to you by referring you to another document filed separately with the SEC. The information incorporated by reference is considered to be a part of this prospectus supplement. Any information incorporated by reference in this prospectus supplement that we file with the SEC after the date of this prospectus supplement will automatically update and supersede information contained in this prospectus supplement. Our SEC file number is 001-10706.

We are incorporating by reference in this prospectus supplement the documents listed below and any future filings that we make with the SEC under Sections 13(a), 13(c), 14 or 15(d) of the Securities Exchange Act of 1934, as amended (the "Exchange Act") prior to the termination of this offering, excluding any portions of any such documents that are "furnished" but not "filed" for purposes of the Exchange Act:

• • our Annual Report on Form 10-K for the fiscal year ended December 31, 2017 (including the portions of our Proxy Statement on Schedule 14A, filed on March 13, 2018, incorporated by reference therein);

• • our Quarterly Reports on Form 10-Q for the quarterly periods ended March 31, 2018, June 30, 2018 and September 30, 2018; and

• • our Current Reports on Forms 8-K filed on January 24, 2018, February 8, 2018, April 26, 2018, July 24, 2018, July 31, 2018, October 18, 2018 and January 11, 2019.

S-ii

Upon written or oral request, we will provide-at no cost to the requester-a copy of any or all of the information that has been incorporated by reference in this prospectus supplement but not delivered with the prospectus supplement. You may request a copy of these filings, other than exhibits unless that exhibit is specifically incorporated by reference into that filing, at no cost, by writing or telephoning Comerica at the following address:

Investor Relations

Comerica Incorporated Comerica Bank Tower

1717 Main Street

Dallas, Texas 75201 Telephone number: [phone]

You should rely only on the information incorporated by reference or provided in this prospectus supplement and the accompanying prospectus.

S-iii

Cautionary Statement Regarding Forward-Looking Statements

This prospectus supplement, the accompanying prospectus and the documents incorporated by reference in this prospectus supplement and the accompanying prospectus include forward-looking statements as defined in the Private Securities Litigation Reform Act of 1995. Any statements in this report that are not historical facts are forward-looking statements as defined in the Private Securities Litigation Reform Act of 1995. Words such as "anticipates," "believes," "contemplates," "feels," "expects," "estimates," "seeks," "strives," "plans," "intends," "outlook," "forecast," "position," "target," "mission," "assume," "achievable," "potential," "strategy," "goal," "aspiration," "opportunity," "initiative," "outcome," "continue," "remain," "maintain," "on track," "trend," "objective," "looks forward," "projects," "models" and variations of such words and similar expressions, or future or conditional verbs such as "will," "would," "should," "could," "might," "can," "may" or similar expressions, as they relate to Comerica or its management, are intended to identify forward-looking statements. These forward-looking statements are predicated on the beliefs and assumptions of Comerica's management based on information known to Comerica's management as of the date such statements were made and do not purport to speak as of any other date. Forward-looking statements may include descriptions of plans and objectives of Comerica's management for future or past operations, products or services, including the GEAR Up initiative, and forecasts of Comerica's revenue, earnings or other measures of economic performance, including statements of profitability, business segments and subsidiaries as well as estimates of the economic benefits of the GEAR Up initiative, and estimates of credit trends and global stability. Such statements reflect the view of Comerica's management as of this date with respect to future events and are subject to risks and uncertainties. Should one or more of these risks materialize or should underlying beliefs or assumptions prove incorrect, Comerica's actual results could differ materially from those discussed. Factors that could cause or contribute to such differences are changes in general economic, political or industry conditions; changes in monetary and fiscal policies; whether Comerica may achieve opportunities for revenue enhancements and efficiency improvements under the GEAR Up initiative, or changes in the scope or assumptions underlying the GEAR Up initiative; operational difficulties, failure of technology infrastructure or information security incidents; reliance on other companies to provide certain key components of business infrastructure; Comerica's ability to maintain adequate sources of funding and liquidity; the effects of more stringent capital or liquidity requirements; declines or other changes in the businesses or industries of Comerica's customers; unfavorable developments concerning credit quality; changes in regulation or oversight; changes in the financial markets, including fluctuations in interest rates and their impact on deposit pricing; transitions away from LIBOR towards new interest rate benchmarks; reductions in Comerica's credit rating; damage to Comerica's reputation; Comerica's ability to utilize technology to efficiently and effectively develop, market and deliver new products and services; competitive product and pricing pressures among financial institutions within Comerica's markets; the interdependence of financial service companies; the implementation of Comerica's strategies and business initiatives; changes in customer behavior; management's ability to maintain and expand customer relationships; the effectiveness of methods of reducing risk exposures; the effects of catastrophic events including, but not limited to, hurricanes, tornadoes, earthquakes, fires, droughts and floods; the effects of recent tax reform and potential legislative, administrative or judicial changes or interpretations related to these and other tax regulations; any future strategic acquisitions or divestitures; management's ability to retain key officers and employees; the impact of legal and regulatory proceedings or determinations; the effects of terrorist activities and other hostilities; changes in accounting standards; the critical nature of Comerica's accounting policies and the volatility of Comerica's stock price. Comerica cautions that the foregoing list of factors is not all-inclusive. For discussion of factors that may cause actual results to differ from expectations, please refer to Comerica's filings with the SEC. In particular, please refer to "Item 1A. Risk Factors" beginning on page 11 of Comerica's Annual Report on Form 10-K for the year ended December 31, 2017 and "Item 1A. Risk Factors" beginning on page 59 of Comerica's Quarterly Report on Form 10-Q for the quarter ended June 30, 2018. Forward-looking statements speak only as of the date they are made. Comerica does not undertake to update forward-looking statements to reflect facts, circumstances, assumptions or events that occur after the date the forward-looking statements are made, except as required by law. For any forward-looking statements made in this prospectus supplement, the accompanying prospectus or the documents incorporated by reference, Comerica claims the protection of the safe harbor for forward-looking statements contained in the Private Securities Litigation Reform Act of 1995.

S-iv