13G Filing: Springhouse Capital Takes Big Stake in Fifth Street Asset Management Inc. (FSAM)

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

Schedule 13G

Under the Securities Exchange Act of 1934

(Amendment No.     )¹

FIFTH STREET ASSET MANAGEMENT INC.

(Name of Issuer)

(Title of Class of Securities)

31679P109

(CUSIP Number)

February 22, 2016

(Date of Event Which Requires Filing of this Statement)

Check the appropriate box to
designate the rule pursuant to which this Schedule is filed:

¨ Rule 13d-1(b)

x Rule 13d-1(c)

¨ Rule 13d-1(d)

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 (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).

(Continued on following page(s))

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Item 1(a). Name of Issuer:

Fifth Street Asset Management Inc.

Item 1(b). Address of Issuers Principal Executive Offices:

777 West Putnam Avenue, 3rd Floor, Greenwich, Connecticut 06830

Item 2(a). Name(s) of Person(s) Filing:

The Fund, the General Partner, Management, Springhouse and Mr. Gaines are
collectively referred to as the Reporting Persons.

Item 2(b). Address of Principal Business Office or, if None, Residence:

18 Burr Farms Road, Westport, Connecticut 06880

Item 2(c). Citizenship:

The Fund is
a Cayman Islands exempted limited partnership. The General Partner is a Cayman Islands exempted company. Management is a Delaware limited partnership. Springhouse is a Delaware limited liability company. Mr. Gaines is a citizen of the United
States.

Item 2(d). Title of Class of Securities:

Class A common stock, par value $0.01 per share

Item 2(e). CUSIP Number:

31679P109

Item 3. If this statement is filed pursuant to §§240.13d-1(b) or 240.13d-2(b) or (c), check whether the person filing is a:

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Not applicable

Item 4. Ownership:

The Fund directly beneficially owns 575,498 shares.

The General Partner is the general partner of the Fund and, as a result, may be deemed to beneficially own shares owned by the Fund.

Management is the investment manager of the Fund and, as a result, may be deemed to beneficially own shares owned by the Fund.

Springhouse is the general partner of Management and, as a result, may be deemed to beneficially own shares owned by the Fund.

Mr. Gaines serves as managing member of Springhouse and as a director of the General Partner and, as a result, may be deemed to
beneficially own shares owned by Springhouse.

9.95%, based on 5,782,392 shares outstanding as of November 20,
2015, according to the Issuers quarterly report on Form 10-Q filed on November 24, 2015.

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Item 5. Ownership of Five Percent or Less of a Class:

If this statement is being filed to report the fact that as of the date hereof the reporting person has ceased to be the beneficial owner of
more than five percent of the class of securities, check the following. ¨

Item 6. Ownership of
More than Five Percent on Behalf of Another Person:

Not applicable

Item 7. Identification and Classification of the Subsidiary Which Acquired the Security Being Reported on by the Parent Holding Company:

Not applicable

Item 8. Identification
and Classification of Members of the Group:

Not applicable

Item 9. Notice of Dissolution of Group:

Not applicable

Item 10. Certification.

By signing below, I certify that, to the best of my knowledge and belief, the securities referred to above were not acquired and are
not held for the purpose of or with the effect of changing or influencing the control of the issuer of the securities and were not acquired and are not held in connection with or as a participant in any transaction having that purpose or effect.

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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.

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