UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

SCHEDULE 13D

(Rule 13d-102)

INFORMATION TO BE INCLUDED IN STATEMENTS FILED PURSUANT

TO RULE 13d-1(a) AND AMENDMENTS THERETO FILED PURSUANT TO

RULE 13d-2(a)

(Amendment No. 4)*

Cumulus Media Inc.

(Name of Issuer)

Class A Common Stock, par value $0.01 per share

(Title of Class of Securities)

231082108

(CUSIP Number)

Ross A. Oliver, Esq.

Crestview Partners II GP, L.P.

667 Madison Avenue

New York, NY 10065

(212) 906-0700

(Name, Address and Telephone Number of Person

Authorized to Receive Notices and Communications)

November 25, 2015

(Date of Event which Requires Filing of this Statement)

If the filing person has previously filed a statement on Schedule 13G to report the acquisition that is the subject of this Schedule 13D, and is filing this schedule because of §§240.13d-1(e), 240.13d-1(f) or 240.13d-1(g), check the following box ¨.

Note: Schedules filed in paper format shall include a signed original and five copies of the schedule, including all exhibits. See §240.13d-7 for other parties to whom copies are to be sent.

* The remainder of this cover page shall be filled out for a reporting person’s initial filing on this form with respect to the subject class of securities, and for any subsequent amendment containing information which would alter disclosures provided in a prior cover page.

The information required on the remainder of this cover page shall not be deemed to be “filed” for the purpose of Section 18 of the Securities Exchange Act of 1934 (the “Act”) or otherwise subject to the liabilities of that section of the Act but shall be subject to all other provisions of the Act (however, see the Notes).

CUSIP No. 231082108

SCHEDULE 13D

* Includes 40,486 restricted shares of Class A Common Stock granted by the Issuer to Jeffrey Marcus on May 14, 2015 and 40,486 restricted shares of Class A Common Stock granted by the Issuer to Brian Cassidy on May 14, 2015 in respect of their respective service on the Board. Each of Mr. Marcus and Mr. Cassidy is a Partner of Crestview Advisors, L.L.C. These securities will fully vest on May 14, 2016. In connection with the vesting of these securities, Messrs. Marcus and Cassidy will assign all rights, title and interest in these securities to Crestview Advisors, L.L.C.

CUSIP No. 231082108

SCHEDULE 13D

CUSIP No. 231082108

SCHEDULE 13D

CUSIP No. 231082108

SCHEDULE 13D

CUSIP No. 231082108

SCHEDULE 13D

CUSIP No. 231082108

SCHEDULE 13D

CUSIP No. 231082108

SCHEDULE 13D

CUSIP No. 231082108

SCHEDULE 13D

CUSIP No. 231082108

SCHEDULE 13D

* Includes 40,486 restricted shares of Class A Common Stock granted by the Issuer to Jeffrey Marcus on May 14, 2015 and 40,486 restricted shares of Class A Common Stock granted by the Issuer to Brian Cassidy on May 14, 2015 in respect of their respective service on the Board. Each of Mr. Marcus and Mr. Cassidy is a Partner of Crestview Advisors, L.L.C. These securities will fully vest on May 14, 2016. In connection with the vesting of these securities, Messrs. Marcus and Cassidy will assign all rights, title and interest in these securities to Crestview Advisors, L.L.C.

Pursuant to Rule 13d-2(a) of the General Rules and Regulations under the Exchange Act, the undersigned hereby amends the Schedule 13D originally filed on September 26, 2011, as amended by Amendment 1 thereto filed on November 22, 2011, Amendment 2 thereto filed on December 14, 2012 and Amendment 3 thereto filed on April 29, 2015 (the “Schedule 13D”), relating to the Class A common stock, par value $0.01 per share (“Class A Common Stock”), of Cumulus Media Inc. (the “Issuer”).

Item 2. Identity and Background.

Item 2 of the Schedule 13D is hereby amended by deleting the first paragraph and replacing it with the following:

“The names of the persons filing this statement are Crestview Partners II GP, L.P. (“Crestview GP”), Crestview Radio Investors, LLC (“Crestview Radio Investors”), Crestview Partners II, L.P. (“DE Fund”), Crestview Partners II (TE), L.P. (“TE Fund”), Crestview Partners II (FF), L.P. (“FF Fund”), Crestview Offshore Holdings II (Cayman), L.P. (“Cayman Fund”), Crestview Offshore Holdings II (FF Cayman), L.P. (“FF Cayman Fund”), Crestview Offshore Holdings II (892 Cayman), L.P. (“892 Cayman Fund,” and together with DE Fund, TE Fund, FF Fund, Cayman Fund and FF Cayman Fund, the “Crestview Funds”) and Crestview Advisors, L.L.C. (“Crestview Advisors” and, together with Crestview Radio Investors, the Crestview Funds and Crestview GP, the “Reporting Persons” and each, a “Reporting Person”). Crestview GP serves as the general partner of the Crestview Funds. The general partner of Crestview GP is Crestview, L.L.C. Each of the Crestview Funds is a private investment fund and a member of Crestview Radio Investors, which is a special purpose investment vehicle. DE Fund, TE Fund, FF Fund, Cayman Fund, FF Cayman Fund and 892 Cayman Fund are 74.5%, 2.4%, 4.1%, 11.4%, 1.3% and 6.3% members, respectively, in Crestview Radio Investors, which is the record owner of 64,970,642 shares of Class A Common Stock and a warrant to purchase 7,815,553 shares of Class A Common Stock. Crestview Advisors provides investment advisory and management services to the Crestview Funds. The address of the principal office of each of the Reporting Persons and Crestview, L.L.C. is 667 Madison Avenue, New York, New York 10065.”

Item 3. Source and Amount of Funds or Other Consideration.

Item 3 of the Schedule 13D is hereby amended to add the following at the end of such section:

“Crestview Radio Investors purchased 4,335,331 shares of the Class A Common Stock in a series of open market transactions during the period between May 8, 2015 and November 25, 2015. The aggregate purchase price for such 4,335,331 shares of the Class A Common Stock was $4,802,801 which full amount was paid by Crestview Radio Investors from its working capital (funds available for investment and available lines of credit).

On May 14, 2015, the Issuer granted 40,486 restricted shares of Class A Common Stock to Jeffrey Marcus and 40,486 restricted shares of Class A Common Stock to Brian Cassidy in respect of their service on the Board. Each of Mr. Marcus and Mr. Cassidy is a Partner of Crestview Advisors, L.L.C. These securities will fully vest on May 14, 2016. In connection with the vesting of these securities, Messrs. Marcus and Cassidy will assign all rights, title and interest in these securities to Crestview Advisors, L.L.C.”

Item 5. Interest in Securities of the Issuer.

Item 5(a) of the Schedule 13D is hereby amended and restated in its entirety as follows: 

“(a) Amount beneficially owned:

As of November 25, 2015, the Reporting Persons beneficially owned in the aggregate 72,953,315 shares of the Class A Common Stock. Such shares constitute 30.27% of the outstanding shares of the Class A Common Stock, based on (i) 233,171,452 shares of Class A Common Stock outstanding as of September 30, 2015 as reported in the Issuer’s Quarterly Report filed on Form 10-Q with the Securities and Exchange Commission (“SEC”) on November 5, 2015, plus (ii) 7,815,553 shares of the Class A Common Stock, which may be acquired upon exercise of the Class A Warrant.

Crestview GP is the general partner of each of the Crestview Funds. Each of the Crestview Funds is a member of Crestview Radio Investors. DE Fund, TE Fund, FF Fund, Cayman Fund, FF Cayman Fund and 892 Cayman Fund are 74.5%, 2.4%, 4.1%, 11.4%, 1.3% and 6.3% members, respectively, in Crestview Radio Investors, which is the record owner of 64,970,642 shares of the Class A Common Stock and the Class A Warrant to purchase 7,815,553 shares of the Class A Common Stock.

Crestview Advisors owns 86,148 shares of Class A Common Stock.

Jeffrey Marcus holds 40,486 restricted shares of Class A Common Stock granted by the Issuer to Mr. Marcus in respect of his service on the Board. Mr. Marcus is a Partner of Crestview Advisors. These securities will fully vest on May 14, 2016. In connection with the vesting of these securities, Mr. Marcus will assign all rights, title and interest in these securities to Crestview Advisors.

Brian Cassidy holds 40,486 restricted shares of Class A Common Stock granted by the Issuer to Mr. Cassidy in respect of his service on the Board. Mr. Cassidy is a Partner of Crestview Advisors. These securities will fully vest on May 14, 2016. In connection with the vesting of these securities, Mr. Cassidy will assign all rights, title and interest in these securities to Crestview Advisors.

Crestview GP may be deemed to beneficially own the 86,148 shares of Class A Common Stock owned by Crestview Advisors and the 80,972 restricted shares of Class A Common Stock held by Messrs. Marcus and Cassidy that, upon vesting on May 14, 2016, will be assigned to Crestview Advisors.

Each Reporting Person disclaims beneficial ownership of the reported securities except and to the extent of its pecuniary interest therein.

(b) Number of shares as to which such person has:

(i) Sole power to vote or direct the vote:

See item 7 on Cover Pages to this Schedule 13D.

(ii) Shared power to vote or to direct the vote:

See item 8 on Cover Pages to this Schedule 13D.

(iii) Sole power to dispose or to direct the disposition of:

See item 9 on Cover Pages to this Schedule 13D.

(iv) Shared power to dispose or to direct the disposition of:

See item 10 on Cover Pages to this Schedule 13D.

(c) Except for the acquisitions set forth on Schedule A hereto, the persons identified in Item 2 of this Schedule 13D have not effected any transaction in shares of the Class A Common Stock during the preceding 60 days.

(d) Except as described in this Schedule 13D, no person has the power to direct the receipt of dividends on or the proceeds of sales of, the shares of the Class A Common Stock owned by the Reporting Persons.

(e) Not applicable.”

Item 7. Material to be Filed as Exhibits.

SIGNATURE

After reasonable inquiry and to the best of my knowledge and belief, I certify that the information set forth in this statement is true, complete and correct.

Date: November 25, 2015

Attention. Intentional misstatements or omissions of fact constitute Federal criminal violations (see 18 U.S.C. 1001).

Schedule A

(All transactions were made in the open market)

(1) The amount of shares represents the aggregate amount of shares that were purchased in the sales that were executed on each corresponding day.

(2) The price represents the approximate weighted average price per share of sales that were executed on each corresponding day.

EXHIBIT 1

JOINT FILING AGREEMENT

In accordance with Rule 13d-1(k) under the Act, the undersigned hereby agree (i) to the joint filing on behalf of each of them of a statement on Schedule 13D (including amendments thereto) with respect to the Class A common stock, $0.01 par value per share, of Cumulus Media Inc. and (ii) that this Joint Filing Agreement be included as an exhibit to such joint filing, provided that, as contemplated by Section 13d-1(k)(1)(ii) of the Act, no person shall be responsible for the completeness and accuracy of the information concerning the other persons making the filing unless such person knows or has reason to believe such information is inaccurate.

In evidence thereof, the undersigned, being duly authorized, hereby execute this Agreement this November 25, 2015.