Item 1.01 Entry into a Definitive Material Agreement.

On August 6, 2012, Duff & Phelps Corporation (the "Company") entered into an underwriting agreement (the "Underwriting Agreement") with Shinsei Bank, Limited, Vestar Capital Partners IV, L.P. and Vestar/D&P Holdings, LLC, as selling stockholders (the "Selling Stockholders"), and Goldman, Sachs & Co., as the sole underwriter (the "Underwriter"), pursuant to which the Selling Stockholders agreed to sell 3,000,000 shares of Class A common stock, par value $0.01 per share (the "Class A Common Stock"), to the Underwriter. The Selling Stockholders have also granted the Underwriter a 30-day option to purchase an additional 450,000 shares of Class A Common Stock, in aggregate. The shares of Class A Common Stock are being offered and sold pursuant to a prospectus supplement, dated August 6, 2012, and related prospectus, dated May 29, 2012, each filed with the Securities and Exchange Commission, relating to the Company's shelf registration statement on Form S-3 (File No. 333-181132). A copy of the Underwriting Agreement is attached hereto as Exhibit 1.1 and is incorporated by reference herein.

The Underwriting Agreement contains representations and warranties by each of the parties thereto. These representations and warranties have been made solely for the benefit of the other parties to the Underwriting Agreement and:

• should not be treated as categorical statements of fact, but rather as a way of allocating the risk to one of the parties if those statements prove to be inaccurate;

• may have been qualified in the Underwriting Agreement by disclosures that were made to the other party in connection with the negotiation of the Underwriting Agreement;

• may apply contract standards of "materiality" that are different from "materiality" under the applicable securities laws; and

• were made only as of the date of the Underwriting Agreement or such other date or dates as may be specified in the Underwriting Agreement.

Item 9.01 Financial Statements and Exhibits.

(d) Exhibits.
1.1 Underwriting Agreement, dated August 6, 2012.
5.1 Opinion of Skadden, Arps, Slate, Meagher & Flom LLP.
23.1 Consent of Skadden, Arps, Slate, Meagher & Flom LLP (included in Exhibit 5.1).

---