The information in this preliminary prospectus is not complete and may be changed. We may not sell these securities until the registration statement filed with the Securities and Exchange Commission is effective. This preliminary prospectus is not an offer to sell these securities and it is not soliciting an offer to buy these securities in any jurisdiction where the offer or sale is not permitted.

Subject to Completion: Dated March 22, 2016

As filed with the Securities and Exchange Commission on March 22, 2016

Registration No. [            ]

UNITED STATES SECURITIES AND EXCHANGE COMMISSION

WASHINGTON, DC 20549

PRE-EFFECTIVE AMENDMENT NO. 1

TO FORM S-1

REGISTRATION STATEMENT

UNDER

THE SECURITIES ACT OF 1933

EQUINOX FRONTIER FUNDS

(a Delaware Statutory Trust)

EQUINOX FRONTIER DIVERSIFIED FUND; EQUINOX FRONTIER MASTERS FUND;

EQUINOX FRONTIER LONG/SHORT COMMODITY FUND

(Exact Name of Registrant as Specified in its Charter)

Copies to:

Matthew K. Kerfoot, Esq.

Dechert LLP

1095 Avenue of the Americas

New York, New York 10036 (212) 641-5694

Approximate date of commencement of proposed sale to the public: As soon as practicable after the effective date of this Registration Statement.

If any of the securities being registered on this Form are to be offered on a delayed or continuous basis pursuant to Rule 415 under the Securities Act of 1933, check the following box.  x

If this Form is filed to register additional securities for an offering pursuant to Rule 462(b) under the Securities Act, please check the following box and list the Securities Act registration statement number of the earlier effective registration statement for the same offering.  ¨

If this Form is a post-effective amendment filed pursuant to Rule 462(c) under the Securities Act, check the following box and list the Securities Act registration statement number of the earlier effective registration statement for the same offering.  ¨

If this Form is a post-effective amendment filed pursuant to Rule 462(d) under the Securities Act, check the following box and list the Securities Act registration statement number of the earlier effective registration statement for the same offering.  ¨

Indicate by check mark whether the registrant is a large accelerated filer, an accelerated filer, a non-accelerated filer or a smaller reporting company. See the definitions of “large accelerated filer,” “accelerated filer” and “smaller reporting company” in Rule 12b-2 of the Exchange Act. (Check One):

CALCULATION OF REGISTRATION FEE

N/A is entered in the table for the proposed maximum aggregate offering for certain class 3 units and class 3a units for which no registration fee is payable because they are issuable only in exchange for other units being registered at the same time.

No registration fee is payable for the class 3 units of each of Equinox Frontier Diversified Fund or Equinox Frontier Masters Fund, and for the class 3a units of Equinox Frontier Long/Short Commodity Fund, in reliance upon Rule 457(i) under the Securities Act, because such class 3 units, and class 3a units, will be issued only in exchange for class 1 units and class 2 units, and class 1a units and class 2a units, of such series which were registered at the same time.

Pursuant to the provisions of Rule 429 of the rules and regulations of the Commission under the Securities Act, the form of prospectus herein also relates to units registered under the registrant’s Registration Statement on Form S-1 (Reg. No. [●]) declared effective on [●] and the registrant’s Registration Statement on Form S-1 (Reg. No. [●]) declared effective on [●].

The registrant hereby amends this Registration Statement on such date or dates as may be necessary to delay its effective date until the registrant shall file a further amendment which specifically states that this Registration Statement shall thereafter become effective in accordance with Section 8(a) of the Securities Act or until this Registration Statement shall become effective on such date as the Commission, acting pursuant to said Section 8(a), may determine.

EQUINOX FRONTIER FUNDS

CROSS REFERENCE SHEET

EQUINOX FRONTIER FUNDS

The date of this Part II is [            ], 2016

PART II

INFORMATION NOT REQUIRED IN PROSPECTUS

Item 13. Other Expenses of Issuance and Distribution.

The expenses to be incurred in connection with the offering are as follows:

The managing owner is responsible for the payment of all of the ordinary expenses associated with the offering of each series of units (including those set forth in the table above), except for the initial service fee, if any, and no series will be required to reimburse these expenses.

Item 14. Indemnification of Directors and Officers.

Reference is made to Section 4.6 of Article IV at page 18 of the Registrant’s Amended and Restated Declaration of Trust and Trust Agreement dated April 21, 2009, annexed to the prospectus as Exhibit A, which provides for indemnification of the managing owner and affiliates of the managing owner under certain circumstances.

Item 15. Recent Sales of Unregistered Securities.

The following table provides information regarding the sale of unregistered units by the registrant within the past three years. The number of units listed below for each transaction is the aggregate number of units in the particular series of the trust purchased in such transaction. The consideration listed below for each transaction is, except as otherwise noted, the aggregate amount of cash paid for the units purchased. For each transaction reported below, the price per unit was the net asset value per unit at the time of the transaction and the managing owner of the trust was the purchaser of the units. No underwriting discount or sales commission was paid or received with respect to any of the transactions reported below. The registrant claims an exemption from registration for each of the transactions listed below under Section 4(2) of the Securities Act as a sale by an issuer not involving a public offering.

Item 16. Exhibits and Financial Statement Schedules.

(a) The following documents (unless otherwise indicated) are filed herewith and made a part of this Registration Statement:

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(b) The financial statements of the registrant are incorporated by reference from the registrant’s Annual Report on Form 10-K, filed with the SEC on March [•], 2016.

Item 17. Undertakings.

Registrant hereby undertakes: (a) to file, during any period in which offers or sales are being made, a post-effective amendment to the Registration Statement: (i) to include any prospectus required by Section 10(a)(3) of the Securities Act, (ii) to reflect in the prospectus any facts or events arising after the effective date of the Registration Statement (or the most recent post-effective amendment thereof) which, individually or in the aggregate, represent a fundamental change in the information set forth in the Registration Statement and (iii) to include any material information with respect to the plan of distribution not previously disclosed in the Registration Statement or any material change to such information in the Registration Statement; (b) that, for the purpose of determining any liability under the Securities Act, each such post-effective amendment shall be deemed to be a new Registration Statement relating to the securities offered herein, and the offering of such securities at that time shall be deemed to be the initial bona fide offering thereof; (c) to remove from registration by means of a post-effective amendment any of the securities being registered which remain unsold at the termination of the offering; (d) that, for the purpose of determining liability under the Securities Act to any purchaser, each prospectus filed pursuant to Rule 424(b) as part of the Registration Statement relating to an offering, other than registration statements relying on Rule 430B or other than prospectuses filed in reliance on Rule 430A, shall be deemed to be part of and included in the Registration Statement as of the date it is first used after effectiveness. Provided, however, that no statement made in the Registration Statement or prospectus that is part of the Registration Statement or made in a document incorporated or deemed incorporated by reference into the Registration Statement or prospectus that is part of the Registration Statement will, as to a purchaser with a time of contract of sale prior to such first use, supersede or modify any statement that was made in the Registration Statement or prospectus that was part of the Registration Statement or made in any such document immediately prior to such date of first use; and (e) that, for the purpose of determining liability of the registrant under the Securities Act to any purchaser in the initial distribution

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of the securities, the registrant undertakes that in a primary offering of securities of the registrant pursuant to the Registration Statement, regardless of the underwriting method used to sell the securities to the purchaser, if the securities are offered or sold to such purchaser by means of any of the following communications, the registrant will be a seller to the purchaser and will be considered to offer or sell such securities to such purchaser: (i) any preliminary prospectus or prospectus of the registrant relating to the offering required to be filed pursuant to Rule 424, (ii) any free writing prospectus relating to the offering prepared by or on behalf of the registrant or used or referred to by the registrant, (iii) the portion of any other free writing prospectus relating to the offering containing material information about the registrant or its securities provided by or on behalf of the registrant and (iv) any other communication that is an offer in the offering made by the registrant to the purchaser.

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Insofar as indemnification for liabilities arising under the Securities Act may be permitted to the managing owner of registrant, including its directors, officers and controlling persons, registrant has been advised that in the opinion of the Securities and Exchange Commission such indemnification is against public policy as expressed in the Securities Act and is, therefore, unenforceable. In the event that a claim for indemnification against such liabilities (other than for expenses incurred in a successful defense) is asserted against registrant by the managing owner under the trust agreement or otherwise, registrant will, unless in the opinion of its counsel the matter has been settled by controlling precedent, submit to a court of appropriate jurisdiction the question whether such indemnification by it is against public policy as expressed in the Securities Act and will be governed by the final adjudication of such issue.

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SIGNATURES

Pursuant to the requirements of the Securities Act of 1933, as amended, the Registrant has duly caused this Pre-Effective Amendment No. 1 to Form S-1 Registration Statement to be signed on its behalf by the undersigned, thereunto duly authorized, in the City of Denver, State of Colorado, on the 22nd day of March, 2016.

Pursuant to the requirements of the Securities Act of 1933, as amended, this Pre-Effective Amendment No. 1 to Form S-1 Registration Statement has been signed below by the following persons in their capacities as directors or officers of Equinox Fund Management, LLC, the managing owner of the registrant, on the dates indicated below.

(Being the principal executive officer, the principal financial officer, the principal accounting officer and a majority of the members of the Executive Committee of Equinox Fund Management, LLC)

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Pursuant to the requirements of the Securities Act of 1933, as amended, the Registrant has duly caused this Pre-Effective Amendment No. 1 to Form S-1 Registration Statement to be signed on its behalf by the undersigned, thereunto duly authorized, in the City of Denver, State of Colorado, on the 22nd day of March, 2016.

Pursuant to the requirements of the Securities Act of 1933, as amended, this Pre-Effective Amendment No. 1 to Form S-1 Registration Statement has been signed below by the following persons in their capacities as directors or officers of Equinox Fund Management, LLC, the managing owner of the registrant, on the dates indicated below.

(Being the principal executive officer, the principal financial officer, the principal accounting officer and a majority of the members of the Executive Committee of Equinox Fund Management, LLC)

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Pursuant to the requirements of the Securities Act of 1933, as amended, the Registrant has duly caused this Pre-Effective Amendment No. 1 to Form S-1 Registration Statement to be signed on its behalf by the undersigned, thereunto duly authorized, in the City of Denver, State of Colorado, on the 22nd day of March, 2016.

Pursuant to the requirements of the Securities Act of 1933, as amended, this Pre-Effective Amendment No. 1 to Form S-1 Registration Statement has been signed below by the following persons in their capacities as directors or officers of Equinox Fund Management, LLC, the managing owner of the registrant, on the dates indicated below.

(Being the principal executive officer, the principal financial officer, the principal accounting officer and a majority of the members of the Executive Committee of Equinox Fund Management, LLC)

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Pursuant to the requirements of the Securities Act of 1933, as amended, the Registrant has duly caused this Pre-Effective Amendment No. 1 to Form S-1 Registration Statement to be signed on its behalf by the undersigned, thereunto duly authorized, in the City of Denver, State of Colorado, on the 22nd day of March, 2016.

Pursuant to the requirements of the Securities Act of 1933, as amended, this Pre-Effective Amendment No. 1 to Form S-1 Registration Statement has been signed below by the following persons in their capacities as directors or officers of Equinox Fund Management, LLC, the managing owner of the registrant, on the dates indicated below.

(Being the principal executive officer, the principal financial officer, the principal accounting officer and a majority of the members of the Executive Committee of Equinox Fund Management, LLC)

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