United States
SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

SCHEDULE 13G

Under the Securities Exchange Act of 1934

(Amendment No. 1)*

Name of Issuer - Swift Energy Co.

Title or Class of Securities - Common Stock

CUSIP Number - 870738101

Check the following box if a fee is being paid with this
statement [  ].


Cusip No. 870738101

Page 2 of 6 Pages

1.   Name of  Reporting  Person  (S.S.  or  I.R.S.  Identification  No. of above
     person)

     American Century Investment Management, Inc. - 44-0640487


2.   Check the appropriate box if a member of a group* - N/A

3.   SEC Use Only

4.   Citizenship or place of organization

     Delaware


5.   Sole voting power

     N/A

6.   Shared voting power

     N/A

7.   Sole dispositive power

     N/A

8.   Shared dispositive power

     N/A

9.   Aggregate amount beneficially owned by each reporting person

     N/A

10.  Check box if the aggregate amount in Row (9) excludes certain shares

     N/A


11.  Percent of class represented by amount in Row 9

     N/A

12.  Type of reporting person*

     IA


Cusip No. 870738101

Page 3 of 6 Pages

1.   Name of  Reporting  Person  (S.S.  or  I.R.S.  Identification  No. of above
     person)

     American Century Capital Portfolios, Inc. - 43-1646043


2.   Check the appropriate box if a member of a group* - N/A

3.   SEC Use Only

4.   Citizenship or place of organization

     Maryland


5.   Sole voting power

     N/A

6.   Shared voting power

     N/A

7.   Sole dispositive power

     N/A

8.   Shared dispositive power

     N/A

9.   Aggregate amount beneficially owned by each reporting person

     N/A

10.  Check box if the aggregate amount in Row (9) excludes certain shares

     N/A


11.  Percent of class represented by amount in Row 9

     N/A

12.  Type of reporting person*

     IV


SCHEDULE 13G


Item 1(a).   NAME OF ISSUER

     Swift Energy Co.

Item 1(b).   ADDRESS OF ISSUER'S PRINCIPAL EXECUTIVE OFFICES

     16825 Northchase Drive
     Suite 400
     Houston, TX 77060

Item 2(a).   NAME OF PERSONS FILING

     American Century Investment  Management,  Inc., on its behalf and on behalf
     of:

     American Century Capital Portfolios, Inc.


Item 2(b).   ADDRESS OF PRINCIPAL BUSINESS OFFICE OR, IF NONE, RESIDENCE

     4500 Main Street
     P.O. Box 418210
     Kansas City, MO 64141-9210
     Attn:  David H. Reinmiller


Item 2(c).   CITIZENSHIP

     Delaware


Item 2(d).   TITLE OF CLASS OF SECURITIES

     Common Stock


Item 2(e).     CUSIP NO.

     870738101


Item 3.   IF THIS  STATEMENT  IS FILED  PURSUANT TO RULES  13d-1(b) OR 13d-2(b),
          CHECK WHETHER THE PERSON FILING IS A

     (g)  [ X ]   Registered Investment Adviser, in accordance with
               Rule 13d-1(b)(ii)(E) (Note:  See Item 7).


Item 4.   OWNERSHIP

     (a)  Aggregate amount beneficially owned:

          N/A

     (b)  Percent of class:

          N/A

     (c)  Number of shares as to which such person has:

          (i)  sole power to vote or to direct the vote:

               N/A

          (ii) shared power to vote or to direct the vote:

               N/A

          (iii)sole power to dispose or to direct the disposition of:

               N/A

          (iv) shared power to dispose or to direct the disposition of:

               N/A

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 [X].


Item 6.   OWNERSHIP OF MORE THAN FIVE PERCENT ON BEHALF OF ANOTHER PERSON

    American  Century  Investment   Management,   Inc.  ("ACIM"),  a  registered
investment adviser, manages, pursuant to management agreements,  the investments
of thirteen  registered  investment  companies,  American  Century Mutual Funds,
Inc.,  American  Century  World Mutual Funds,  Inc.,  American  Century  Capital
Portfolios,  Inc., American Century Variable Portfolios,  Inc., American Century
Premium  Reserves,  Inc.,  American Century Strategic Asset  Allocations,  Inc.,
American Century Municipal Trust,  American Century  Quantitative  Equity Funds,
Inc.,  American  Century   International  Bond  Funds,  Inc.,  American  Century
Investment Trust,  American Century  Government  Income Trust,  American Century
Target Maturities Trust, and American Century California  Tax-Free and Municipal
Funds, Inc., and manages,  pursuant to sub-advisory agreements,  the investments
of four  registered  investment  companies,  American  Skandia  Trust,  American
Skandia Advisor Funds,  Inc., Style Select Series,  Inc., and Mainstay UP Series
Fund, Inc. ACIM also manages the assets of institutional  investor accounts. The
securities  that are the  subject of this  report are owned by and held for such
investment companies and separate institutional investor accounts. Any dividends
received from such  securities,  or the proceeds of any sale of such securities,
are for the benefit of, and are held for such investment  companies and separate
institutional investor accounts.


Item 7.   IDENTIFICATION AND CLASSIFICATION OF THE SUBSIDIARY WHICH ACQUIRED THE
          SECURITY BEING REPORTED ON BY THE PARENT HOLDING COMPANY

     N/A


Item 8.   IDENTIFICATION AND CLASSIFICATION OF MEMBERS OF THE GROUP

     N/A


Item 9.   NOTICE OF DISSOLUTION OF GROUP

     N/A


Item 10.  CERTIFICATION

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


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.



February 10, 2000              AMERICAN CENTURY INVESTMENT MANAGEMENT, INC.
     Date

                               By: /s/David C. Tucker

                                   David C. Tucker
                                   Senior Vice President
                                   and General Counsel

EXHIBIT A

Rule 13d-1(f)(1)(iii) Agreement


     Each of the  undersigned  hereby  agrees and consents to the  execution and
joint filing on its behalf by American Century  Investment  Management,  Inc. of
this Schedule 13G respecting the  beneficial  ownership of the securities  which
are the subject of this schedule at December 31, 1999.

     Dated this 10th day of February, 2000.

                                American Century Investment Management, Inc.


                                By: /s/David C. Tucker

                                    David C. Tucker
                                    Senior Vice President
                                    and General Counsel



                                American Century Capital Portfolios, Inc.


                                By: /s/David C. Tucker

                                    David C. Tucker
                                    Vice President