<PAGE>

                                    FORM 10-Q


                       SECURITIES AND EXCHANGE COMMISSION

                             Washington, D.C. 20549


    [ X ]         QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d) OF
                              THE SECURITIES EXCHANGE ACT OF 1934

                  For the quarterly period ended June 30, 1998

                                       OR

    [   ]         TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF
                              THE SECURITIES EXCHANGE ACT OF 1934

        For the transition period from _______________ to ______________

                         Commission File number 0-18359


                          SWIFT ENERGY MANAGED PENSION

                         ASSETS PARTNERSHIP 1989-B, LTD.
             (Exact name of registrant as specified in its charter)

<TABLE>
<S>                                           <C>       
                  Texas                                    76-0282457
(State or other jurisdiction of organization) (I.R.S. Employer Identification No.)
</TABLE>


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

                                  (281)874-2700
              (Registrant's telephone number, including area code)

                                      None
              (Former name, former address and former fiscal year,
                          if changed since last report)


Indicate by check mark whether the Registrant (1) has filed all reports required
to be filed by Section 13 or 15(d) of the Securities Exchange Act of 1934 during
the  preceding 12 months (or for such  shorter  period that the  Registrant  was
required  to file  such  reports),  and  (2) has  been  subject  to such  filing
requirements for the past 90 days.

                                 Yes  X     No
                                     ---



<PAGE>


                          SWIFT ENERGY MANAGED PENSION
                         ASSETS PARTNERSHIP 1989-B, LTD.

                                      INDEX



<TABLE>
<CAPTION>
PART I.    FINANCIAL INFORMATION                                                      PAGE
      <S>                                                                             <C>
      ITEM 1.    Financial Statements

            Balance Sheets

                - June 30, 1998 and December 31, 1997                                  3

            Statements of Operations

                - Three month and six month periods ended June 30, 1998 and 1997       4

            Statements of Cash Flows

                - Six month periods ended June 30, 1998 and 1997                       5

            Notes to Financial Statements                                              6

      ITEM 2.    Management's Discussion and Analysis of Financial
                     Condition and Results of Operations                               9

PART II.    OTHER INFORMATION                                                         11


SIGNATURES                                                                            12
</TABLE>



<PAGE>

                          SWIFT ENERGY MANAGED PENSION
                         ASSETS PARTNERSHIP 1989-B, LTD.
                                 BALANCE SHEETS



<TABLE>
<CAPTION>
                                                                                          June 30,           December 31,
                                                                                            1998                 1997
                                                                                       ---------------     ----------------
                                                                                        (Unaudited)
         <S>                                                                           <C>                  <C>           
         ASSETS:

         Current Assets:
              Cash and cash equivalents                                                $        1,477       $       67,645
              Nonoperating interests income receivable                                         93,677              143,694
                                                                                       ---------------     ----------------
                  Total Current Assets                                                         95,154              211,339
                                                                                       ---------------     ----------------
         Nonoperating interests in oil and gas
              properties, using full cost accounting                                        3,888,675            3,823,672
         Less-Accumulated amortization                                                     (2,526,980)          (2,430,419)
                                                                                       ---------------     ----------------
                                                                                            1,361,695            1,393,253
                                                                                       ---------------     ----------------
                                                                                       $    1,456,849       $    1,604,592
                                                                                       ===============     ================


         LIABILITIES AND PARTNERS' CAPITAL:

         Current Liabilities:
              Accounts Payable                                                         $      121,790       $        5,379
                                                                                       ---------------     ----------------

         Limited Partners' Capital (39,830.64 Limited Partnership Units;
                                   $100 per unit)                                           1,320,618            1,579,937
         General Partners' Capital                                                             14,441               19,276
                                                                                       ---------------     ----------------
                  Total Partners' Capital                                                   1,335,059            1,599,213
                                                                                       ---------------     ----------------
                                                                                       $    1,456,849       $    1,604,592
                                                                                       ===============     ================
</TABLE>


                 See accompanying notes to financial statements.

                                        3


<PAGE>

                          SWIFT ENERGY MANAGED PENSION
                         ASSETS PARTNERSHIP 1989-B, LTD.
                            STATEMENTS OF OPERATIONS
                                   (Unaudited)





<TABLE>
<CAPTION>
                                                     Three Months Ended                  Six Months Ended
                                                          June 30,                           June 30,
                                              ---------------------------------  ---------------------------------
                                                   1998              1997             1998              1997
                                              ---------------   ---------------  ---------------   ---------------
<S>                                           <C>               <C>              <C>               <C>            
REVENUES:
   Income from nonoperating interests         $        72,378   $        81,575  $       152,352   $       256,798
   Interest income                                         47             1,935              304             3,227
                                              ---------------   ---------------  ---------------   ---------------
                                                       72,425            83,510          152,656           260,025
                                              ---------------   ---------------  ---------------   ---------------

COSTS AND EXPENSES:
   Amortization                                        47,151            47,410           96,561           105,264
   General and administrative                          18,503            21,548           34,715            44,971
                                              ---------------   ---------------  ---------------   ---------------
                                                       65,654            68,958          131,276           150,235
                                              ---------------   ---------------  ---------------   ---------------
NET INCOME (LOSS)                             $         6,771   $        14,552  $        21,380   $       109,790
                                              ===============   ===============  ===============   ===============



Limited Partners' net income (loss)
   per unit                                   $           .17   $           .37  $           .54   $          2.76
                                              ===============   ===============  ===============   ===============
</TABLE>


                 See accompanying notes to financial statements.

                                        4


<PAGE>


                          SWIFT ENERGY MANAGED PENSION
                         ASSETS PARTNERSHIP 1989-B, LTD.
                            STATEMENTS OF CASH FLOWS
                                   (Unaudited)

<TABLE>
<CAPTION>
                                                                                           Six Months Ended
                                                                                               June 30,
                                                                               ---------------------------------------
                                                                                     1998                    1997
                                                                               ---------------          ---------------
<S>                                                                             <C>                     <C>            
CASH FLOWS FROM OPERATING ACTIVITIES:
    Income (loss)                                                               $       21,380          $       109,790
    Adjustments to reconcile income (loss) to
      net cash provided by operations:
      Amortization                                                                      96,561                  105,264
      Change in assets and liabilities:
        (Increase) decrease in nonoperating interests income receivable                 50,017                   46,473
        (Increase) decrease in other current assets                                         --                   59,014
        Increase (decrease) in accounts payable                                        116,411                   (1,732)
                                                                               ---------------          ---------------
      Net cash provided by (used in) operating activities                              284,369                  318,809
                                                                               ---------------          ---------------
CASH FLOWS FROM INVESTING ACTIVITIES:
    Additions to nonoperating interests in oil and gas properties                      (65,003)                 (26,127)
    Proceeds from sales of nonoperting interests in oil and gas properties                  --                    2,140
                                                                               ---------------          ---------------
      Net cash provided by (used in) investing activities                              (65,003)                 (23,987)
                                                                               ---------------          ---------------
CASH FLOWS FROM FINANCING ACTIVITIES:
    Cash distributions to partners                                                    (285,534)                (278,823)
                                                                               ---------------          ---------------
NET INCREASE (DECREASE) IN CASH AND CASH EQUIVALENTS                                   (66,168)                  15,999
                                                                               ---------------          ---------------
CASH AND CASH EQUIVALENTS AT BEGINNING OF PERIOD                                        67,645                  142,628
                                                                               ---------------          ---------------
CASH AND CASH EQUIVALENTS AT END OF PERIOD                                      $        1,477          $       158,627
                                                                               ===============          ===============
Supplemental disclosure of cash flow information:
   Cash paid during the period for interest                                     $          781          $            --
                                                                               ===============          ===============
</TABLE>


                 See accompanying notes to financial statements.

                                        5


<PAGE>

                          SWIFT ENERGY MANAGED PENSION
                         ASSETS PARTNERSHIP 1989-B, LTD.
                          NOTES TO FINANCIAL STATEMENTS
                                   (UNAUDITED)


(1)  General Information -

                  The financial statements included herein have been prepared by
        the  Partnership  and are  unaudited  except  for the  balance  sheet at
        December  31,  1997  which has been  taken  from the  audited  financial
        statements at that date. The financial  statements reflect  adjustments,
        all of which  were of a  normal  recurring  nature,  which  are,  in the
        opinion  of  the  managing   general   partner   necessary  for  a  fair
        presentation.  Certain  information  and footnote  disclosures  normally
        included in financial  statements  prepared in accordance with generally
        accepted  accounting  principles have been omitted pursuant to the rules
        and regulations of the Securities and Exchange Commission  ("SEC").  The
        Partnership  believes adequate disclosure is provided by the information
        presented.  The financial  statements should be read in conjunction with
        the audited  financial  statements  and the notes included in the latest
        Form 10-K.

(2)  Organization and Terms of Partnership Agreement -

                  Swift Energy Managed Pension Assets Partnership 1989-B,  Ltd.,
        a Texas limited partnership ("the  Partnership"),  was formed on May 31,
        1989,  for the purpose of purchasing net profits  interests,  overriding
        royalty  interests and royalty  interests  (collectively,  "nonoperating
        interests") in producing oil and gas properties  within the  continental
        United States. Swift Energy Company ("Swift"), a Texas corporation,  and
        VJM Corporation  ("VJM"),  a California  corporation,  serve as Managing
        General  Partner  and  Special  General  Partner  of  the   Partnership,
        respectively.  The general  partners  are required to  contribute  up to
        1/99th of limited partner net  contributions.  The 480 limited  partners
        made total capital contributions of $3,983,064.

                  Nonoperating  interests  acquisition  costs and the management
        fee are borne 99 percent by the limited  partners and one percent by the
        general  partners.  Organization and syndication costs were borne solely
        by the limited partners.

                  Generally,  all continuing costs (including development costs,
        operating costs,  general and  administrative  reimbursements and direct
        expenses) and revenues are allocated 90 percent to the limited  partners
        and ten percent to the general partners. If prior to partnership payout,
        however,  the cash  distribution  rate for a  certain  period  equals or
        exceeds  17.5  percent,  then for the  following  calendar  year,  these
        continuing  costs and  revenues  will be  allocated  85  percent  to the
        limited  partners  and  15  percent  to  the  general  partners.   After
        partnership  payout,  continuing  costs and  revenues  will be shared 85
        percent by the limited partners, and 15 percent by the general partners,
        even if the cash  distribution  rate is less than 17.5  percent.  During
        1992 and 1991, the cash distribution rate (as defined in the Partnership
        Agreement)  exceeded  17.5  percent  and  thus,  in 1993 and  1992,  the
        continuing  costs and  revenues  were  shared 85 percent by the  limited
        partners  and 15 percent by the general  partners.  During  1997,  1996,
        1995, 1994 and 1993, the cash  distribution rate fell below 17.5 percent
        and  thus,  in 1997,  1996,  1995 and  1994,  the  continuing  costs and
        revenues  were shared 90 percent by the limited  partners and 10 percent
        by the general partners. Payout occurred in January 1998; therefore, for
        1998  and  each  year  remaining  in the  life of the  partnership,  the
        continuing  costs and revenues  will be shared 85 percent by the limited
        partners and 15 percent by the general partners.

(3)  Significant Accounting Policies -

       Use of Estimates --

                  The  preparation  of financial  statements in conformity  with
        generally accepted  accounting  principles  requires  management to make
        estimates and assumptions that affect the reported amounts of assets and
        liabilities  at the date of the  financial  statements  and the reported
        amounts of revenues and expenses  during the  reporting  period.  Actual
        results could differ from estimates. Certain reclassifications have been
        made to prior year amounts to conform to the current year presentation.

                                       6


<PAGE>


                          SWIFT ENERGY MANAGED PENSION
                         ASSETS PARTNERSHIP 1989-B, LTD.
                    NOTES TO FINANCIAL STATEMENTS (CONTINUED)
                                   (UNAUDITED)


Nonoperating Interests in Oil and Gas Properties --

                  The Partnership accounts for its ownership interest in oil and
        gas properties using the proportionate consolidation method, whereby the
        Partnership's  share of assets,  liabilities,  revenues  and expenses is
        included in the appropriate classification in the financial statement.

                  For financial  reporting purposes the Partnership  follows the
        "full-cost"  method of accounting for nonoperating  interests in oil and
        gas property costs. Under this method of accounting,  all costs incurred
        in the acquisition of  nonoperating  interests in oil and gas properties
        are capitalized.  The unamortized cost of nonoperating  interests in oil
        and gas  properties is limited to the "ceiling  limitation"  (calculated
        separately for the Partnership,  limited partners and general partners).
        The  "ceiling  limitation"  is  calculated  on  a  quarterly  basis  and
        represents the estimated future net revenues from nonoperating interests
        in proved  properties  using current  prices  discounted at ten percent.
        Proceeds from the sale or disposition of  nonoperating  interests in oil
        and  gas  properties  are  treated  as a  reduction  of the  cost of the
        nonoperating  interests  with no gains or  losses  recognized  except in
        significant transactions.

                  The Partnership computes the provision for amortization of oil
        and gas properties on the units-of-production method. Under this method,
        the provision is calculated by multiplying the total unamortized cost of
        oil and gas  properties  by an overall rate  determined  by dividing the
        physical  units of oil and gas  produced  during the period by the total
        estimated proved oil and gas reserves at the beginning of the period.

                  The calculation of the "ceiling  limitation" and the provision
        for  depreciation,  depletion and  amortization is based on estimates of
        proved reserves. There are numerous uncertainties inherent in estimating
        quantities  of proved  reserves  and in  projecting  the future rates of
        production,  timing and plan of development. The accuracy of any reserve
        estimate  is a  function  of  the  quality  of  available  data  and  of
        engineering  and  geological  interpretation  and  judgment.  Results of
        drilling,  testing and production subsequent to the date of the estimate
        may justify revision of such estimate.  Accordingly,  reserve  estimates
        are  often  different  from  the  quantities  of oil  and gas  that  are
        ultimately recovered.

(4)  Related-Party Transactions -

                  An  affiliate  of  the  Special  General  Partner,  as  Dealer
        Manager,  received  $99,177 for managing and  overseeing the offering of
        the limited  partnership units. A one-time management fee of $99,577 was
        paid to Swift for services performed for the Partnership.

                  The  Partnership  entered  into a Net Profits  and  Overriding
        Royalty Interests Agreement ("NP/OR Agreement") with Swift Energy Income
        Partners 1989-B, Ltd. ("Operating  Partnership"),  managed by Swift, for
        the purpose of acquiring nonoperating interests in producing oil and gas
        properties.   Under  terms  of  the  NP/OR   Agreement,   the  Operating
        Partnership will convey to the Partnership nonoperating interests in the
        aggregate net profits (i.e., oil and gas sales net of related  operating
        costs) of the properties  acquired equal to its  proportionate  share of
        the property acquisition costs.

(5)  Vulnerability Due to Certain Concentrations -

                  The  Partnership's  revenues are primarily the result of sales
        of its oil and natural gas production.  Market prices of oil and natural
        gas may fluctuate and adversely affect operating results.

                                       7

<PAGE>


                          SWIFT ENERGY MANAGED PENSION
                         ASSETS PARTNERSHIP 1989-B, LTD.
                    NOTES TO FINANCIAL STATEMENTS (CONTINUED)
                                   (UNAUDITED)


                  In the normal  course of  business,  the  Partnership  extends
        credit,  primarily in the form of monthly oil and gas sales receivables,
        to various  companies  in the oil and gas  industry  which  results in a
        concentration  of credit risk. This  concentration of credit risk may be
        affected by changes in economic or other  conditions and may accordingly
        impact the  Partnership's  overall  credit risk.  However,  the Managing
        General  Partner  believes  that  the  risk is  mitigated  by the  size,
        reputation, and nature of the companies to which the Partnership extends
        credit.  In  addition,   the  Partnership  generally  does  not  require
        collateral or other security to support customer receivables.

(6)  Fair Value of Financial Instruments -

                  The Partnership's  financial  instruments  consist of cash and
        cash equivalents and short-term  receivables and payables.  The carrying
        amounts  approximate  fair value due to the highly  liquid nature of the
        short-term instruments.


                                       8


<PAGE>

                          SWIFT ENERGY MANAGED PENSION
                         ASSETS PARTNERSHIP 1989-B, LTD.
                MANAGEMENT'S DISCUSSION AND ANALYSIS OF FINANCIAL
                       CONDITION AND RESULTS OF OPERATIONS


GENERAL

      The  Partnership  is formed for the purpose of investing  in  nonoperating
interests in producing oil and gas  properties  located  within the  continental
United States.  In order to accomplish  this, the  Partnership  goes through two
distinct yet  overlapping  phases with respect to its  liquidity  and results of
operations.  When the  Partnership  is formed,  it commences  its  "acquisition"
phase,  with all funds placed in short-term  investments  until required for the
acquisition of nonoperating interests.  Therefore,  the interest earned on these
pre-acquisition  investments  becomes the  primary  cash flow source for initial
partner  distributions.  As the Partnership acquires  nonoperating  interests in
producing properties,  net cash from ownership of nonoperating interests becomes
available  for  distribution,  along  with  the  investment  income.  After  all
partnership funds have been expended on nonoperating  interests in producing oil
and gas properties,  the Partnership enters its "operations"  phase. During this
phase,  income  from  nonoperating  interests  in oil  and gas  sales  generates
substantially all revenues, and distributions to partners reflect those revenues
less all  associated  partnership  expenses.  The  Partnership  may also  derive
proceeds  from  the  sale of  nonoperating  interests  in  acquired  oil and gas
properties,  when the sale of such  interests  is  economically  appropriate  or
preferable to continued operations.

LIQUIDITY AND CAPITAL RESOURCES

      Oil and gas reserves are depleting  assets and therefore often  experience
significant  production  declines each year from the date of acquisition through
the end of the life of the  property.  The primary  source of  liquidity  to the
Partnership comes almost entirely from the income generated from the sale of oil
and gas produced from ownership  interests in oil and gas  properties.  Net cash
provided by  operating  activities  totaled  $284,369  and  $318,809 for the six
months ended June 30, 1998 and 1997, respectively.  This source of liquidity and
the related results of operations, and in turn cash distributions,  will decline
in  future  periods  as the oil and gas  produced  from  these  properties  also
declines while production and general and administrative costs remain relatively
stable making it unlikely that the  Partnership  will hold the properties  until
they are fully depleted,  but will likely liquidate when a substantial  majority
of the reserves  have been  produced.  The  Partnership  has expended all of the
partners' net commitments available for property acquisitions and development by
acquiring producing oil and gas properties. The partnership invests primarily in
proved  producing  properties with nominal levels of future costs of development
for  proven  but  undeveloped  reserves.  Significant  purchases  of  additional
reserves or extensive drilling activity are not anticipated.  Cash distributions
totaled  $285,534  and $278,823 for the six months ended June 30, 1998 and 1997,
respectively.

      Under the NP/OR Agreement, the Managing General Partner acquires interests
in oil and gas properties  from outside  parties and sells these interests to an
affiliated  operating  partnership,  who  in  turn  creates  and  sells  to  the
Partnership  nonoperating  interests in these same oil and gas  properties.  The
Managing  General Partner expects funds available from net profits  interests to
be distributed to the partners.

RESULTS OF OPERATIONS

      The  following  analysis  explains  changes  in the  revenue  and  expense
categories  for the quarter ended June 30, 1998 (current  quarter) when compared
to the quarter  ended June 30,  1997  (corresponding  quarter),  and for the six
months ended June 30, 1998  (current  period),  when  compared to the six months
ended June 30, 1997 (corresponding period).

Three Months Ended June 30, 1998 and 1997

      Income  from  nonoperating  interests  decreased  11 percent in the second
quarter of 1998 when  compared  to the same  quarter in 1997.  Oil and gas sales
declined  $27,443 or 19 percent in the second  quarter of 1998 when  compared to
the  corresponding  quarter in 1997,  primarily  due to decreased oil prices and
production.  Oil prices  decreased  29 percent or $5.06/BBL  and oil  production
declined 30 percent.  Declines in revenues were partially  offset by an increase
in gas  production  of 21 percent and gas prices of 9 percent or  $.18/MCF  when
compared to second quarter 1997 prices.

                                       9

<PAGE>

                          SWIFT ENERGY MANAGED PENSION
                         ASSETS PARTNERSHIP 1989-B, LTD.
                MANAGEMENT'S DISCUSSION AND ANALYSIS OF FINANCIAL
                 CONDITION AND RESULTS OF OPERATIONS (CONTINUED)


      Associated  amortization  expense  decreased  1  percent  or  $259 in 1998
compared to second  quarter  1997,  also  related to the  decline in  production
volumes.

Six Months Ended June 30, 1998 and 1997

      Income from nonoperating  interests  decreased 41 percent in the first six
months  of 1998 when  compared  to the same  period  in 1997.  Oil and gas sales
declined $134,662 or 36 percent in the first six months of 1998 when compared to
the corresponding period in 1997, primarily due to decreased oil and gas prices.
A decline  in oil  prices of 34  percent  or  $6.63/BBL  and in gas prices of 21
percent or $.58/MCF, had a significant impact on partnership performance.  Also,
current  period  oil and gas  production  declined  18  percent  and 7  percent,
respectively,  when compared to the same period in 1997, further contributing to
decreased revenues.

      Associated  amortization  expense  decreased  8 percent  or $8,703 in 1998
compared  to the first six  months  of 1997,  also  related  to the  decline  in
production volumes.

      During 1998,  partnership  revenues  and costs will be shared  between the
limited partners and general partners in a 85:15 ratio.


                                       10


<PAGE>


                          SWIFT ENERGY MANAGED PENSION
                         ASSETS PARTNERSHIP 1989-B, LTD
                           PART II - OTHER INFORMATION




ITEM 5.    OTHER INFORMATION


                                     -NONE-




                                       11

<PAGE>



                                   SIGNATURES



Pursuant to the  requirements of Section 13 or 15(d) of the Securities  Exchange
Act of 1934,  the  Registrant  has duly  caused  this report to be signed on its
behalf by the undersigned thereunto duly authorized.


                                        SWIFT ENERGY MANAGED PENSION
                                        ASSETS PARTNERSHIP 1989-B, LTD.
                                        (Registrant)

                             By:        SWIFT ENERGY COMPANY
                                        Managing General Partner

Date:     August 4, 1998     By:        /s/ John R. Alden
          --------------                ---------------------------------
                                        John R. Alden
                                        Senior Vice President, Secretary
                                        and Principal Financial Officer

Date:     August 4, 1998     By:        /s/ Alton D. Heckaman, Jr.
          --------------                ---------------------------------
                                        Alton D. Heckaman, Jr.
                                        Vice President, Controller
                                        and Principal Accounting Officer


                                       12