SECURITIES AND EXCHANGE COMMISSION
                     WASHINGTON, D.C.  20549

                            FORM S-6

 For Registration Under the Securities Act of 1933 of Securities
       of Unit Investment Trusts Registered on Form N-8B-2

A.   Exact Name of Trust:             FT 2991

B.   Name of Depositor:               FIRST TRUST PORTFOLIOS L.P.

C.   Complete Address of Depositor's  120 East Liberty Drive
     Principal Executive Offices:     Wheaton, Illinois  60187

D.   Name and Complete Address of
     Agents for Service:              FIRST TRUST PORTFOLIOS L.P.
                                      Attention:  James A. Bowen
                                      120 East Liberty Drive
                                      Suite 400
                                      Wheaton, Illinois  60187

                                      CHAPMAN & CUTLER LLP
                                      Attention: Eric F. Fess
                                      111 West Monroe Street
                                      Chicago, Illinois  60603

E.   Title of Securities
     Being Registered:                An indefinite number of
                                      Units pursuant to Rule
                                      24f-2 promulgated under
                                      the Investment Company Act
                                      of 1940, as amended.

F.   Approximate Date of Proposed
     Sale to the Public:              ____ Check if it is
                                      proposed that this filing
                                      will become effective on
                                      _____ at ____ p.m.
                                      pursuant to Rule 487.

     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 of 1933 or until the Registration  Statement
shall  become  effective on such date as the  Commission,  acting
pursuant to said Section 8(a), may determine.

         Preliminary Prospectus Dated May 25, 2011

                          FT 2991


10,000 Units                       (A Unit Investment Trust)

     The  attached final Prospectus for a prior  Series  of
the Fund is hereby used as a preliminary Prospectus for the
above   stated  Series.   The  narrative  information   and
structure  of  the  attached  final  Prospectus   will   be
substantially the same as that of the final Prospectus  for
this  Series.   Information with respect  to  pricing,  the
number  of  Units, dates and summary information  regarding
the  characteristics of securities to be deposited in  this
Series  is  not  now available and will be different  since
each  Series  has  a  unique  Portfolio.   Accordingly  the
information  contained herein with regard to  the  previous
Series   should  be  considered  as  being   included   for
informational  purposes only. Ratings of the securities  in
this  Series are expected to be comparable to those of  the
securities deposited in the previous Series.

     A registration statement relating to the units of this
Series  will  be  filed  with the Securities  and  Exchange
Commission  but has not yet become effective.   Information
contained  herein  is subject to completion  or  amendment.
Such Units may not be sold nor may offer to buy be accepted
prior  to  the  time  the  registration  statement  becomes
effective.  This Prospectus shall not constitute  an  offer
to  sell  or the solicitation of an offer to buy nor  shall
there  be any sale of the Units in any state in which  such
offer,  solicitation  or sale would be  unlawful  prior  to
registration or qualification under the securities laws  of
any  such state.  (Incorporated herein by reference is  the
final  prospectus for FT 2862 (Registration No. 333-172485)
as  filed  March  25,  2011 which  shall  be  used  as  the
preliminary prospectus for the current series of the Fund.)


                           MEMORANDUM

                          Re:  FT 2991

     The  only  difference  of consequence (except  as  described
below)  between FT 2862, which is the current fund, and FT  2991,
the filing of which this memorandum accompanies, is the change in
the  series number.  The list of securities comprising the  Fund,
the  evaluation, record and distribution dates and other  changes
pertaining  specifically  to the new series,  such  as  size  and
number of Units in the Fund and the statement of condition of the
new Fund, will be filed by amendment.


                            1940 ACT


                      FORMS N-8A AND N-8B-2

     These forms were not filed, as the Form N-8A and Form N-8B-2
filed in respect of Templeton Growth and Treasury Trust, Series 1
and  subsequent series (File No. 811-05903) related also  to  the
subsequent series of the Fund.


                            1933 ACT


                           PROSPECTUS

     The  only significant changes in the Prospectus from the  FT
2862 Prospectus relate to the series number and size and the date
and  various items of information which will be derived from  and
apply specifically to the securities deposited in the Fund.


               CONTENTS OF REGISTRATION STATEMENT


ITEM A    Bonding Arrangements of Depositor:

          First Trust Portfolios L.P. is covered by a Broker's
          Fidelity Bond, in the total amount of $2,000,000, the
          insurer being National Union Fire Insurance Company of
          Pittsburgh.

ITEM B    This Registration Statement on Form S-6 comprises the
          following papers and documents:

          The facing sheet

          The Prospectus

          The signatures

          Exhibits


                               S-1
                           SIGNATURES

     Pursuant to the requirements of the Securities Act of  1933,
the  Registrant,  FT  2991  has  duly  caused  this  Registration
Statement  to  be  signed  on  its  behalf  by  the  undersigned,
thereunto  duly authorized, in the City of Wheaton and  State  of
Illinois on May 25, 2011.

                           FT 2991
                           (Registrant)

                           By:    FIRST TRUST PORTFOLIOS L.P.
                                  (Depositor)



                           By     Jason T. Henry
                                  Senior Vice President


                               S-2

     Pursuant to the requirements of the Securities Act of  1933,
this  Amendment  to the Registration Statement  has  been  signed
below  by  the following person in the capacity and on  the  date
indicated:

      Name                 Title*                   Date

James A. Bowen    Director  of The  Charger )May 25, 2011
                  Corporation, the  General )
                  Partner  of  First  Trust )
                  Portfolios L.P.           )
                                            )
                                            )Jason T. Henry
                                            )Attorney-in-Fact**



       *     The title of the person named herein represents  his
       capacity  in  and  relationship to First Trust  Portfolios
       L.P., Depositor.

       **    An  executed copy of the related power  of  attorney
       was  filed with the Securities and Exchange Commission  in
       connection  with Amendment No. 2 to Form S-6  of  FT  2669
       (File  No. 333-169625) and the same is hereby incorporated
       herein by this reference.


                               S-3
                       CONSENT OF COUNSEL

     The  consent  of  counsel to the use  of  its  name  in  the
Prospectus  included  in  this  Registration  Statement  will  be
contained in its respective opinion to be filed as Exhibit 3.1 of
the Registration Statement.


                CONSENT OF DELOITTE & TOUCHE LLP

     The  consent of Deloitte & Touche LLP to the use of its name
and  to the reference to such firm in the Prospectus included  in
this Registration Statement will be filed by amendment.


              CONSENT OF FIRST TRUST ADVISORS L.P.

     The  consent of First Trust Advisors L.P. to the use of  its
name in the Prospectus included in the Registration Statement  is
filed as Exhibit 4.1 to the Registration Statement.


                               S-4
                          EXHIBIT INDEX

1.1    Form of Standard Terms and Conditions of Trust for FT  785
       among  First  Trust  Portfolios, L.P., as  Depositor,  The
       Bank  of  New  York  Mellon, as Trustee  and  First  Trust
       Advisors  L.P.,  as  Evaluator and  Portfolio  Supervisor.
       (incorporated by reference to Amendment No. 1 to Form  S-6
       [File No. 333-110799] filed on behalf of FT 785).

1.1.1* Form  of  Trust  Agreement for FT 2991 among  First  Trust
       Portfolios  L.P.,  as  Depositor, The  Bank  of  New  York
       Mellon,   as  Trustee,  First  Trust  Advisors  L.P.,   as
       Evaluator and Portfolio Supervisor, and FTP Services  LLC,
       as FTPS Unit Servicing Agent.

1.2    Copy  of Certificate of Limited Partnership of First Trust
       Portfolios  L.P. (incorporated by reference  to  Amendment
       No.  1 to Form S-6 [File No. 33-42683] filed on behalf  of
       The First Trust Special Situations Trust, Series 18).

1.3    Copy   of   Amended   and  Restated  Limited   Partnership
       Agreement  of  First Trust Portfolios, L.P.  (incorporated
       by  reference  to Amendment No. 1 to Form  S-6  [File  No.
       33-42683]  filed  on  behalf of The  First  Trust  Special
       Situations Trust, Series 18).

1.4    Copy   of   Articles  of  Incorporation  of  The   Charger
       Corporation,   the   general  partner   of   First   Trust
       Portfolios  L.P., Depositor (incorporated by reference  to
       Amendment No. 1 to Form S-6 [File No. 33-42683]  filed  on
       behalf  of  The  First  Trust  Special  Situations  Trust,
       Series 18).

1.5    Copy  of  By-Laws of The Charger Corporation, the  general
       partner   of   First  Trust  Portfolios  L.P.,   Depositor
       (incorporated by reference to Amendment No. 2 to Form  S-6
       [File No. 333-169625] filed on behalf of FT 2669).

1.6    Underwriter   Agreement  (incorporated  by  reference   to
       Amendment No. 1 to Form S-6 [File No. 33-42755]  filed  on
       behalf  of  The  First  Trust  Special  Situations  Trust,
       Series 19).

2.1    Copy  of  Certificate of Ownership (included in Exhibit  1.1
       filed herewith on page 2 and incorporated herein by reference).

                               S-5

2.2    Copy  of  Code  of  Ethics  (incorporated  by  reference  to
       Amendment No. 1 to form S-6 [File No. 333-156964] filed on behalf
       of FT 1987).

3.1*   Opinion  of  counsel  as to legality of  Securities  being
       registered.

4.1*   Consent of First Trust Advisors L.P.

6.1    List  of  Directors  and Officers of Depositor  and  other
       related   information  (incorporated   by   reference   to
       Amendment No. 1 to Form S-6 [File No. 33-42683]  filed  on
       behalf  of  The  First  Trust  Special  Situations  Trust,
       Series 18).

7.1    Power of Attorney executed by the Director listed on  page
       S-3  of  this  Registration  Statement  (incorporated   by
       reference  to  Amendment  No. 2  to  Form  S-6  [File  No.
       333-169625] filed on behalf of FT 2669).


___________________________________
* To be filed by amendment.


                               S-6