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): May 10, 2018

STIFEL FINANCIAL CORP.

(Exact name of registrant as specified in its charter)

One Financial Plaza

501 North Broadway

St. Louis, Missouri 63102-2102

(Address of principal executive offices, including zip code)

(Registrant’s telephone number, including area code): (314) 342-2000

Not Applicable

(Former name or former address, if changed since last report)

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):

Indicate by check mark whether the registrant is an emerging growth company as defined in Rule 405 of the Securities Act of 1933 (§230.405 of this chapter) or Rule 12b-2 of the Securities Exchange Act of 1934 (§240.12b-2 of this chapter).

Emerging growth company  ☐

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.  ☐

Item 8.01 Other Events.

On May 10, 2018, Stifel Financial Corp. (the “Company” or “Stifel”) announced that it has entered into a definitive agreement with Business Bancshares, Inc. under which the Company will acquire Business Bancshares, Inc. and its wholly owned subsidiary, The Business Bank of St. Louis. Terms of the transaction were not disclosed, and it is expected to close in the fourth quarter of 2018. A copy of the press release is filed as Exhibit 99.1 hereto and is incorporated by reference.

The information contained in this Current Report on Form 8-K, including Exhibit 99.1 attached hereto, contains certain statements that may be deemed to be “forward-looking statements” within the meaning of Section 27A of the Securities Act of 1933 and Section 21E of the Securities Exchange Act of 1934. All statements in this report not dealing with historical results are forward-looking and are based on various assumptions. The forward-looking statements in this press release are subject to risks and uncertainties that could cause Stifel Financial Corp.’s actual results to differ materially from those expressed in or implied by the statements. Material factors and assumptions could cause actual results to differ materially from current expectations. Factors that may cause actual results to differ materially from those contemplated by such forward-looking statements include, among other things, the following possibilities: the costs or effects of acquisitions or dispositions Stifel may make, whether Stifel is able to obtain any required governmental approvals in connection with any such acquisitions or dispositions, and/or Stifel’s ability to realize the contemplated financial or business benefits associated with any such acquisitions or dispositions; the ability to successfully integrate acquired companies or branch offices and financial advisors; a material adverse change in financial condition; the risk of borrower, depositor, and other customer attrition; a change in general business and economic conditions; changes in the interest rate environment, deposit flows, loan demand, real estate values, and competition; changes in accounting principles, policies, or guidelines; changes in legislation and regulation; other economic, competitive, governmental, regulatory, geopolitical, and technological factors affecting the companies’ operations, pricing, and services; and other risk factors referred to from time to time in filings made by Stifel Financial Corp. with the Securities and Exchange Commission. Stifel Financial Corp. does not undertake to update forward-looking statements to reflect circumstances or events that occur after the date the forward-looking statements are made. Stifel Financial Corp. disclaims any intent or obligation to update these forward-looking statements.

Additional Information

Investors and security holders are urged to carefully review and consider each of Stifel Financial Corp.’s public filings with the Securities and Exchange Commission (the “SEC”), including but not limited to its Annual Reports on Form 10-K, its Current Reports on Form 8-K, and its Quarterly Reports on Form 10-Q. The documents filed by Stifel Financial Corp. with the SEC may be obtained free of charge through a link on Stifel’s website at www.stifel.com or on the SEC website at www.sec.gov. These documents may also be obtained free of charge from Stifel Financial Corp. by requesting them in writing to Stifel Financial Corp., 501 N. Broadway, St. Louis, Missouri 63102, Attention: Joel Jeffrey, or by telephone at (212) 271-3610.

In connection with the proposed transaction, Stifel Financial Corp. intends to file a registration statement on Form S-4 with the SEC that will include a proxy statement of Business Bancshares, Inc. and a prospectus of Stifel Financial Corp., and Stifel Financial Corp. will file other documents regarding the proposed transaction with the SEC. Before making any voting or investment decision, investors and security holders of Stifel Financial Corp. and Business Bancshares, Inc. are urged to carefully read the entire registration statement, proxy statement and prospectus, when they become available, as well as any amendments or supplements to these documents and any other relevant documents filed with the SEC, because they will contain important information about the proposed transaction. A definitive proxy statement will be sent to the shareholders of Business Bancshares, Inc. seeking the required shareholder approvals. Investors and security holders will be able to obtain the registration statement, the proxy statement and the prospectus free of charge from the SEC’s website or from Stifel Financial Corp. by writing to the address set forth in the paragraphs above and from Business Bancshares, Inc. at 8000 Maryland Avenue, Clayton, Missouri 63105.

Proxy Solicitation

Stifel Financial Corp. and Business Bancshares, Inc., and certain of their directors and executive officers, may be deemed to be participants in the solicitation of proxies from the shareholders of Business Bancshares, Inc. in connection with the proposed transaction. Information about the directors and executive officers of Stifel Financial Corp. and their ownership of Stifel Financial Corp. common stock is set forth in Stifel Financial Corp.’s Proxy Statement for the 2018 Annual Meeting of Shareholders filed with the SEC. Information about the directors and executive officers of Business Bancshares, Inc. is available on The Business Bank of St. Louis’s website. Additional information regarding the interests of those participants and other persons who may be deemed participants in the transaction may be obtained by reading the proxy statement and prospectus regarding the proposed transaction when it becomes available.

Item 9.01 Financial Statements and 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.