<PAGE>

                       SECURITIES AND EXCHANGE COMMISSION

                             Washington, D.C. 20549
                            -------------------------

                                    FORM 8-K

                                 CURRENT REPORT

                     Pursuant to Section 13 or 15(d) of the
                         Securities Exchange Act of 1934

       Date of Report (or Date of Earliest Event Reported): June 26, 1998



                          SWIFT ENERGY MANAGED PENSION
                         ASSETS PARTNERSHIP 1990-C, LTD.
             (Exact name of Registrant as specified in its charter)


        TEXAS                    33-15998-10               76-0318473

(State of incorporation    (Commission File Number)       (IRS Employer
    or organization)                                    Identification No.)


                        16825 Northchase Drive, Suite 400
                              Houston, Texas 77060
                    (Address of principal executive offices)



                                 (281) 874-2700
                         (Registrant's telephone number)


<PAGE>

ITEM 2.  Disposition of Assets
         ---------------------

     Substantially  all of the assets of Swift Energy  Mangaged  Pension  Assets
Partnership  1990-C,  Ltd.  (the  "Partnership"),  consisting  of  non-operating
interest  in  real  property  and in  oil  and  gas  reserves  located  therein,
("Property Interests") were sold at auction as of March 1, 1998. The bulk of the
Partnership's  Property  Interests  included partial interest in three fields in
Schleicher  County,  Texas in the  Permian  Basis of West Texas and one field in
Wheeler  County,   Texas.   Collectively,   these  four  fields   accounted  for
approximately  63%  of  the  total  proceeds  received  from  the  sale  of  the
Partnership's Property Interests. The total proceeds to the Partnership,  net of
selling expenses,  were $623,736.  The limited partners' share was $561,362.  An
initial  distribution of proceeds was made to the limited  partners on April 15,
1998,  representing all the assets of the Partnership  except for  insubstantial
amounts  held back for  contingency  purposes.  A small  final  distribution  is
anticipated to be made on or about June 30, 1998, at which time the  Partnership
will dissolve pursuant to the Texas Revised Limited Partnership Act.



                                    SIGNATURES

         Pursuant to the  requirements  of the Securities  Exchange Act of 1934,
the  Registrant  has duly  caused  this report to be signed on its behalf by the
undersigned, hereunto duly authorized person.

Dated: June 26, 1998


                        SWIFT ENERGY MANAGED PENSION ASSETS
                        PARTNERSHIP 1990-C, LTD.


                        By:  Swift Energy Company, as Managing General Partner



                              By:  ----------------------------------------
                                   Alton D. Heckaman, Jr.
                                   Vice President and Controller


                                       2
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SECURITIES AND EXCHANGE COMMISSION

                             Washington, D.C. 20549
                            -------------------------

                                    FORM 8-K

                                 CURRENT REPORT

                     Pursuant to Section 13 or 15(d) of the
                         Securities Exchange Act of 1934

       Date of Report (or Date of Earliest Event Reported): June 26, 1998

                          SWIFT ENERGY MANAGED PENSION
                         ASSETS PARTNERSHIP 1990-C, LTD.
             (Exact name of Registrant as specified in its charter)

        TEXAS                    33-15998-10               76-0318473

(State of incorporation    (Commission File Number)       (IRS Employer
    or organization)                                    Identification No.)

                        16825 Northchase Drive, Suite 400
                              Houston, Texas 77060
                    (Address of principal executive offices)

                                 (281) 874-2700
                         (Registrant's telephone number)
ITEM 2.  Disposition of Assets
         ---------------------

     Substantially  all of the assets of Swift Energy  Mangaged  Pension  Assets
Partnership  1990-C,  Ltd.  (the  "Partnership"),  consisting  of  non-operating
interest  in  real  property  and in  oil  and  gas  reserves  located  therein,
("Property Interests") were sold at auction as of March 1, 1998. The bulk of the
Partnership's  Property  Interests  included partial interest in three fields in
Schleicher  County,  Texas in the  Permian  Basis of West Texas and one field in
Wheeler  County,   Texas.   Collectively,   these  four  fields   accounted  for
approximately  63%  of  the  total  proceeds  received  from  the  sale  of  the
Partnership's Property Interests. The total proceeds to the Partnership,  net of
selling expenses,  were $623,736.  The limited partners' share was $561,362.  An
initial  distribution of proceeds was made to the limited  partners on April 15,
1998,  representing all the assets of the Partnership  except for  insubstantial
amounts  held back for  contingency  purposes.  A small  final  distribution  is
anticipated to be made on or about June 30, 1998, at which time the  Partnership
will dissolve pursuant to the Texas Revised Limited Partnership Act.

                                    SIGNATURES

         Pursuant to the  requirements  of the Securities  Exchange Act of 1934,
the  Registrant  has duly  caused  this report to be signed on its behalf by the
undersigned, hereunto duly authorized person.

Dated: June 26, 1998

                        SWIFT ENERGY MANAGED PENSION ASSETS
                        PARTNERSHIP 1990-C, LTD.

                        By:  Swift Energy Company, as Managing General Partner

                              By:  ----------------------------------------
                                   Alton D. Heckaman, Jr.
                                   Vice President and Controller

                                       2