UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

WASHINGTON, DC 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): September 10, 2014

JPMORGAN CHASE & CO.

(Exact Name of Registrant as Specified in Charter)

DELAWARE

(State or Other Jurisdiction of Incorporation)

Registrant’s telephone number, including area code: (212) 270-6000

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 (see General Instruction A.2. below):

On September 10, 2014, the Company closed a public offering of $3,000,000,000 aggregate principal amount of its 3.875% Subordinated Notes due 2024 (the “Subordinated Notes”). The Subordinated Notes were registered under the Securities Act of 1933, as amended, pursuant to a registration statement on Form S-3 (File No. 333-191692). In connection with this offering, the legal opinion as to the legality of the additional Subordinated Notes is being filed as Exhibit 5.1 to this report.

(d) Exhibits

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.

Dated: September 10, 2014

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EXHIBIT INDEX

4

Exhibit 5.1

September 10, 2014

JPMorgan Chase & Co.

270 Park Avenue

New York, NY 10017

Ladies and Gentlemen:

We have acted as counsel to JPMorgan Chase & Co., a Delaware corporation (the “Company”), in connection with the Registration Statement on Form S-3 (File No. 333-191692) (the “Registration Statement”) filed by the Company with the Securities and Exchange Commission (the “Commission”) under the Securities Act of 1933, as amended, and the issuance by the Company of $3,000,000,000 aggregate principal amount of 3.875% Subordinated Notes due 2024 (the “Securities”) pursuant to the Underwriting Agreement dated September 3, 2014 (the “Underwriting Agreement”) between the Company and the several underwriters named therein. The Securities are being issued under the Subordinated Indenture dated as of March 14, 2014 (the “Indenture”) between the Company and U.S. Bank Trust National Association (the “Trustee”).

We have examined the Registration Statement; the Indenture, which has been filed with the Commission as an exhibit to the Company’s Current Report on Form 8-K filed on March 14, 2014; duplicates of the global notes representing the Securities; and the Underwriting Agreement. We also have examined the originals, or duplicates or certified or conformed copies, of such records, agreements, documents and other instruments and have made such other investigations as we have deemed relevant and necessary in connection with the opinions hereinafter set forth. As to questions of fact material to this opinion, we have relied upon certificates or comparable documents of public officials and of officers and representatives of the Company.

In rendering the opinion set forth below, we have assumed the genuineness of all signatures, the legal capacity of natural persons, the authenticity of all documents submitted to us as originals, the conformity to original documents of all documents submitted to us as duplicates or certified or conformed copies and the authenticity of the originals of such latter documents. We also have assumed that the Indenture is the valid and legally binding obligation of the Trustee.

Based upon the foregoing, and subject to the qualifications, assumptions and limitations stated herein, we are of the opinion that the Securities have been duly authorized, executed and issued by the Company and, assuming due authentication thereof by the Trustee or The Bank of New York Mellon, as authenticating agent under the Indenture on behalf of the Trustee, and upon payment and delivery in accordance with the Underwriting Agreement, the Securities will constitute valid and legally binding obligations of the Company enforceable against the Company in accordance with their terms.

Our opinion set forth above is subject to (i) the effects of bankruptcy, insolvency, fraudulent conveyance, reorganization, moratorium and other similar laws relating to or affecting creditors’ rights generally, (ii) general equitable principles (whether considered in a proceeding in equity or at law) and (iii) an implied covenant of good faith and fair dealing.

We do not express any opinion herein concerning any law other than the law of the State of New York and the Delaware General Corporation Law.

We hereby consent to the filing of this opinion letter as Exhibit 5.1 to the Company’s Current Report on Form 8-K dated September 10, 2014 and to the use of our name under the caption “Legal Opinions” in the prospectus included in the Registration Statement.

Very truly yours,

/s/ Simpson Thacher & Bartlett LLP

SIMPSON THACHER & BARTLETT LLP