<PAGE>   1
                                  UNITED STATES
                       SECURITIES AND EXCHANGE COMMISSION
                              WASHINGTON, DC 20549

                                    FORM 10-K

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

                   FOR THE FISCAL YEAR ENDED DECEMBER 31, 1999

                                       OR

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

               FOR THE TRANSITION PERIOD FROM     N/A     TO     N/A
                                              -----------    -----------

                         COMMISSION FILE NUMBER 0-16540
                                                -------

                              UNITED BANCORP, INC.
           -----------------------------------------------------------
             (Exact name of registrant as specified in its Charter.)

<TABLE>
<CAPTION>
<S><C>
                             OHIO                                             34-1405357
--------------------------------------------------------------    ---------------------------------
(State or other jurisdiction of incorporation or organization)    (IRS) Employer Identification No.)


         201 SOUTH FOURTH STREET, MARTINS FERRY, OHIO                           43935
         --------------------------------------------                         ---------
           (Address of principal executive offices)                           (ZIP Code)
</TABLE>

REGISTRANT'S TELEPHONE NUMBER, INCLUDING AREA CODE:  (740) 633-0445
                                                   -------------------
           SECURITIES REGISTERED PURSUANT TO SECTION 12(b) OF THE ACT:

<TABLE>
<CAPTION>
<S>                                            <C>
COMMON STOCK, PAR VALUE $1.00 A SHARE                NASDAQ REGULAR MARKET (SMALLCAP)
-------------------------------------           ------------------------------------------
       (Title of class)                         (Name of each exchange on which registered)
</TABLE>


           SECURITIES REGISTERED PURSUANT TO SECTION 12(g) OF THE ACT:

                      COMMON STOCK, PAR VALUE $1.00 A SHARE
                      -------------------------------------
                                (Title of class)

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
                                       ---    ---
INDICATE BY CHECK MARK IF DISCLOSURE OF DELINQUENT FILERS PURSUANT TO ITEM 405
OF REGULATION S-K IS NOT CONTAINED HEREIN, AND WILL NOT BE CONTAINED TO THE BEST
OF REGISTRANT'S KNOWLEDGE, IN DEFINITIVE PROXY OR INFORMATION STATEMENTS
INCORPORATED BY REFERENCE IN PART III OF THIS FORM 10-K OR ANY AMENDMENT TO THIS
FORM 10-K. {X }

THE AGGREGATE MARKET VALUE OF THE VOTING STOCK HELD BY NON-AFFILIATES OF THE
REGISTRANT AS OF MARCH 17, 2000.

                   COMMON STOCK, $1.00 PAR VALUE: $36,254,750
                   ------------------------------------------

THE NUMBER OF SHARES OUTSTANDING OF THE REGISTRANT'S CLASSES OF COMMON STOCK AS
OF MARCH 17, 2000.

                 COMMON STOCK, $1.00 PAR VALUE: 2,942,885 SHARES
                 -----------------------------------------------

DOCUMENTS INCORPORATED BY REFERENCE
PORTIONS OF THE ANNUAL SHAREHOLDERS REPORT FOR THE YEAR ENDED DECEMBER 31, 1999
ARE INCORPORATED BY REFERENCE INTO PARTS I AND II, (INDEX ON PAGE 2)

PORTIONS OF THE PROXY STATEMENT FOR THE ANNUAL SHAREHOLDERS MEETING TO BE HELD
APRIL 19, 2000 ARE INCORPORATED BY REFERENCE INTO PART III (INDEX ON PAGE 2).


<PAGE>   2


                         UNITED BANCORP, INC. FORM 10-K

            INDEX OF ITEMS INCORPORATED BY REFERENCE WITHIN FORM 10-K
<TABLE>
<CAPTION>
                      FORM 10-K
PAGE #            ITEM DESCRIPTION                                              REFERENCE DESCRIPTION
------------------------------------------------------------------------------------------------------------------------------------

<S>      <C>                                   <C>
     3     Part I, Item 1, (a)                   Incorporated by reference to Pages 9 - 11 of the Annual Report To Shareholders.

     3     Part I, Item 1, (b)                   Incorporated by reference to Page 36, Note 1 of the Annual Report To Shareholders.

     4     Part I, Item 1, I                     Incorporated by reference to Pages 27 - 28 of the Annual Report To Shareholders.

     5     Part I, Item 1, II, B                 Incorporated by reference to Page 40, Note 2 of the Annual Report To Shareholders.

     7     Part I, Item 1, III, C, 4             Incorporated by reference to Page 47, Note 11 of the Annual Report To Shareholders.

     7     Part I, Item 1, IV                    Incorporated by reference to Page 19 and Pages 36 - 37, Note 1 the Annual Report To
                                                   Shareholders.

     10    Part I, Item 1, V, A                  Incorporated by reference to Page 27 of the Annual Report To Shareholders.

     11    Part I, Item 2                        Incorporated by reference to Pages 9 - 11 of the Annual Report To Shareholders.

     11    Part I, Item 3                        Incorporated by reference to Page 47, Note 10 of the Annual Report To
                                                  Shareholders.

     11    Part II, Item 5                       Incorporated by reference to Page 16 of the Annual Report To Shareholders.

     11    Part II, Item 6                       Incorporated by reference to Inside Back Cover of the Annual Report To
                                                  Shareholders.

     12    Part II, Item 7                       Incorporated by reference to Pages 17 - 30, of the Annual Report To Shareholders.

     12    Part II, Item 7A                      Incorporated by reference to Pages 23 - 25 of the Annual Report To Shareholders.

     12    Part II, Item 8                       Incorporated by reference to Pages 26 and 31 - 52 of the Annual Report To
                                                  Shareholders.

     13    Part III, Item 10                     Incorporated by reference to Pages 4 - 8 of the Proxy Statement.

     13    Part III, Item 11                     Incorporated by reference to Pages 10 - 15 of the Proxy Statement.

     13    Part III, Item 12                     Incorporated by reference to Pages 4 - 8 of the Proxy Statement.

     13    Part III, Item 13                     Incorporated by reference to Page 15 of the Proxy Statement.

     14    Part IV, Item 14, (a), 1              Incorporated by reference to Pages 31 - 52 of the Annual Report To Shareholders.

     14    Part IV, Item 14, (a), 2              Incorporated by reference to Page 26 of the Annual Report To Shareholders.

     14    Part IV, Item 14, (a), 3, Exhibit 10  Incorporated by reference to Page 14 of the Proxy Statement.

     14    Part IV, Item 14, (a), 3, Exhibit 11  Incorporated by reference to Page 38 and Page 52 of the Annual Report To
                                                  Shareholders.
</TABLE>


                                       2
<PAGE>   3


                         UNITED BANCORP, INC. FORM 10-K

PART I

ITEM 1   DESCRIPTION OF BUSINESS

              (a)  GENERAL DEVELOPMENT OF BUSINESS

                   United Bancorp, Inc. (Company) is a multi-bank holding
                   company headquartered in Martins Ferry, Ohio. The Company has
                   two wholly-owned subsidiary banks, The Citizens Savings Bank,
                   Martins Ferry, Ohio (CITIZENS) and The Community Bank,
                   Lancaster, Ohio (COMMUNITY), collectively "Banks". For
                   additional information about the Company's location and
                   description of business, refer to Pages 9 - 11, Corporate
                   Profile, in the Annual Report To Shareholders for the year
                   ended December 31, 1999.

              (b)  FINANCIAL INFORMATION ABOUT BUSINESS SEGMENTS

                   Refer to Page 36, Note 1 of the Annual Report To
                   Shareholders.

              (c)  NARRATIVE DESCRIPTION OF BUSINESS

                   The Company is a multi-bank holding company as defined under
                   the Bank Holding Company Act of 1956, as amended (the "BHC
                   Act"). The BHC Act regulates acquisitions by the Company of
                   voting shares or assets of any bank or other company. The
                   Company is subject to the reporting requirements of, and
                   examination and regulation by, the Board of Governors of the
                   Federal Reserve System, as well as reporting requirements
                   under the Securities and Exchange Commission Act of 1934.

                   The Company's Banks are located in northeastern, eastern, and
                   southeastern Ohio and are engaged in the business of
                   commercial and retail banking in Belmont, Harrison,
                   Jefferson, Tuscarawas, Carroll, Athens, Hocking, and
                   Fairfield counties and the surrounding localities. The Banks
                   provide a broad range of banking and financial services,
                   which include accepting demand, savings and time deposits and
                   granting commercial, real estate and consumer loans. CITIZENS
                   conducts its business through its main office in Martins
                   Ferry, Ohio and nine branches located in Bridgeport,
                   Colerain, Dellroy, Dover, Jewett, New Philadelphia, St.
                   Clairsville, Sherrodsville, and Strasburg, Ohio. In 1999,
                   CITIZENS opened a full service brokerage division known as
                   Brokerage United with securities provided through Raymond
                   James Financial Services, Inc. member NASD/SIPC. COMMUNITY
                   conducts its business through its seven offices in Amesville,
                   Glouster, Lancaster, and Nelsonsville, Ohio.

                   The markets in which the Banks' operate continue to be highly
                   competitive. CITIZENS competes for loans and deposits with
                   other retail commercial banks, savings and loan associations,
                   finance companies, credit unions and other types of financial
                   institutions within the Mid-Ohio valley geographic area along
                   the eastern border of Ohio, extending into the northern
                   panhandle of West Virginia and the Tuscarawas and Carroll
                   County geographic areas of northeastern Ohio. COMMUNITY also
                   encounters similar competition for loans and deposits
                   throughout the Athens, Hocking, and Fairfield County
                   geographic areas of central and southeastern Ohio.

                   On November 12, 1999, President Clinton signed the
                   Graham-Leach-Bliley Act of 1999 ("GLB Act"), which is
                   intended to modernize the financial services industry. The
                   GLB Act sweeps away large parts of a regulatory framework
                   that had its origins in the Depression Era of the 1930s.
                   Effective March 11, 2000, new opportunities will be available
                   for banks, other depository institutions, insurance companies
                   and securities firms to enter into combinations that permit a
                   single financial service organization to offer customers a
                   more complete array of financial products and services. The
                   GLB Act provides a new regulatory framework for regulation
                   through the financial holding company, which will have as its
                   umbrella regulator the Federal Reserve Board. The functional
                   regulation of the financial holding company's separately
                   regulated subsidiaries will be conducted by their primary
                   functional regulator. The GLB Act makes satisfactory or above
                   Community Reinvestment Act compliance for insured depository
                   institutions and their financial holding companies necessary
                   in order for them to engage in new financial activities. The
                   GLB Act provides a federal right to privacy of non-public
                   personal information of individual customers. The Company and
                   Banks are also subject to certain state laws that deal with
                   the use and distribution of non-public personal information



                                       3



<PAGE>   4

                         UNITED BANCORP, INC. FORM 10-K


                   ITEM 1 DESCRIPTION OF BUSINESS (CONTINUED)

              (c)  NARRATIVE DESCRIPTION OF BUSINESS (CONTINUED)

                   The Company's two subsidiary banks are subject to regulation
                   by the Ohio Division of Financial Institutions and the
                   Federal Deposit Insurance Corporation ("FDIC"). The
                   regulations and restrictions affecting the Banks pertain to,
                   among other things, allowable loans, guidelines for allowance
                   for loan losses, accountability for fair and accurate
                   disclosures to customers and regulatory agencies, permissible
                   investments and limitations of risk and regulation of capital
                   requirements for safe and sound operation of the financial
                   institution.

                   The Banks have no single customer or related group of
                   customers whose banking activities, whether through deposits
                   or lending, would have a material impact on the continued
                   earnings capabilities if those activities were removed.

                   The Company itself, as a shell holding company, has no
                   compensated employees. CITIZENS has 81 full time employees,
                   with 25 of these serving in a management capacity and 35 part
                   time employees. COMMUNITY has 38 full time employees, with 13
                   serving in a management capacity and 10 part time employees.
                   The Company considers employee relations to be good at all
                   subsidiary locations.

              (d)  FINANCIAL INFORMATION ABOUT FOREIGN AND DOMESTIC OPERATIONS

                   Not applicable.

            I      DISTRIBUTION OF ASSETS, LIABILITIES AND STOCKHOLDERS EQUITY;
                   INTEREST RATES AND INTEREST DIFFERENTIAL

                   A   Refer to Page 27 of the Annual Report To Shareholders

                   B   Refer to Page 27 of the Annual Report To Shareholders

                   C   Refer to Page 28 of the Annual Report To Shareholders



                                       4


<PAGE>   5



                         UNITED BANCORP, INC. FORM 10-K


ITEM 1   DESCRIPTION OF BUSINESS (CONTINUED)

         II   INVESTMENT PORTFOLIO

                   A    The following table sets forth the carrying amount of
                        securities at December 31, 1999, 1998 and 1997:
<TABLE>
<CAPTION>

                                                                             DECEMBER 31,
                                                            ----------------------------------------------------
                                  (In thousands)                  1999            1998                1997
                                                            -------------  ----------------  -------------------
                         <S>                                <C>            <C>                <C>
                          AVAILABLE FOR SALE
                           US Treasury obligations           $         -    $        1,509     $          3,308
                           US Agency obligations                  65,952            67,506               37,199
                           Mortgage-backed obligations             2,017             3,028                3,785
                           State and municipal obligations        14,187             2,197                  577
                           Other securities                        3,206             1,597                1,134
                                                            -------------  ----------------  -------------------
                                                             $    85,362    $       75,837     $         46,003
                                                            =============  ================  ===================

                                   (In thousands)
                          HELD TO MATURITY
                           US Agency obligations             $     2,494    $            -     $          7,500
                           State and municipal obligations         7,300            21,848               21,560
                                                            -------------  ----------------  -------------------
                                                             $     9,794    $       21,848     $         29,060
                                                            =============  ================  ===================
</TABLE>

                   B    Refer to Page 40, Note 2 of the Annual Report To
                        Shareholders.

                   C    Excluding holdings of U.S. Agency, there were no
                        investments in securities of any one issuer exceeding
                        10% of the Company's consolidated shareholders' equity
                        at December 31, 1999.

         III  LOAN PORTFOLIO

                   A    TYPES OF LOANS

                        The amounts of gross loans outstanding at December 31,
                        1999, 1998, 1997, 1996 and 1995 are shown in the
                        following table according to types of loans:
<TABLE>
<CAPTION>

                                                                          DECEMBER 31,
                                   ----------------------------------------------------------------------------------
                                       1999            1998                1997              1996           1995
                                   -------------  ----------------  -------------------  -------------  -------------
          (In thousands)
<S>                                <C>            <C>               <C>                  <C>            <C>
Commercial loans                       $ 15,463          $ 12,912             $ 16,636       $ 15,065       $ 13,606
Commercial real estate loans             60,305            54,195               49,189         41,565         35,926
Real estate loans                        51,357            49,438               49,857         52,955         51,042
Installment loans                        53,391            47,676               55,795         56,931         56,795
                                   -------------  ----------------  -------------------  -------------  -------------
  Total loans                          $180,516         $ 164,221            $ 171,477      $ 166,516      $ 157,369
                                   =============  ================  ===================  =============  =============
</TABLE>





       Construction loans were not significant for the periods discussed.








                                       5
<PAGE>   6



                         UNITED BANCORP, INC. FORM 10-K

ITEM 1   DESCRIPTION OF BUSINESS (CONTINUED)

         III LOAN PORTFOLIO (CONTINUED)

                  B   MATURITIES AND SENSITIVITIES OF LOANS TO CHANGES IN
                      INTEREST RATES

                      The following is a schedule of commercial and commercial
                      real estate loans at December 31, 1999 maturing within the
                      various time frames indicated:
<TABLE>
<CAPTION>
                                   ONE YEAR       ONE THROUGH           AFTER
         (In thousands)             OR LESS       FIVE YEARS          FIVE YEARS          TOTAL
                                  ------------  ----------------  -------------------  -------------
<S>                               <C>           <C>               <C>                  <C>
  Commercial loans                   $ 13,204          $  1,536             $    723       $ 15,463
  Commercial real estate loans         24,762            21,190               14,353         60,305
                                  ------------  ----------------  -------------------  -------------
    Total                            $ 37,966          $ 22,726             $ 15,076       $ 75,768
                                  ============  ================  ===================  =============
</TABLE>



                      The following is a schedule of fixed rate and variable
                      rate commercial and commercial real estate loans at
                      December 31, 1999 due to mature after one year:
<TABLE>
<CAPTION>
         (In thousands)           FIXED RATE     VARIABLE RATE     TOTAL > ONE YEAR
                                  ------------  ----------------  -------------------
<S>                               <C>           <C>               <C>
  Commercial loans                   $  2,259          $      -             $  2,259
  Commercial real estate loans         14,053            21,490               35,543
                                  ------------  ----------------  -------------------
    Total                            $ 16,312          $ 21,490             $ 37,802
                                  ============  ================  ===================
</TABLE>



                      Variable rate loans are those loans with floating or
                      adjustable interest rates.

                  C   RISK ELEMENTS

                  1.  NONACCRUAL, PAST DUE, RESTRUCTURED AND IMPAIRED LOANS

                      The following schedule summarizes nonaccrual loans,
                      accruing loans which are contractually 90 days or more
                      past due, troubled debt restructurings and impaired loans
                      at December 31, 1999, 1998, 1997, 1996 and 1995:
<TABLE>
<CAPTION>
                                                                      DECEMBER 31,
                                             ------------------------------------------------------------
               (In thousands)                   1999        1998        1997        1996         1995
                                             -----------  ----------  ----------  ----------  -----------
<S>                                          <C>          <C>         <C>         <C>         <C>
Nonaccrual basis                                  $ 987       $ 399       $ 480       $ 667        $ 622
Accruing loans 90 days or greater past due           36         150         319         256          544
Troubled debt restructuring                         N/A         N/A         N/A         N/A          N/A

Impaired loans                                       (1)         (1)         (1)         (1)          (1)
</TABLE>




  (1) Loans considered impaired under the provisions of SFAS No. 114 and
  interest recognized on a cash received basis were not considered material
  during any of the periods presented.

  The additional amount of interest income that would have been recorded on
  nonaccrual loans, had they been current, totaled $47,000 for the year-ended
  December 31, 1999.





                                       6
<PAGE>   7




                         UNITED BANCORP, INC. FORM 10-K


ITEM 1   DESCRIPTION OF BUSINESS (CONTINUED)

         III LOAN PORTFOLIO (CONTINUED)

                  1.  NONACCRUAL, PAST DUE, RESTRUCTURED AND IMPAIRED LOANS
                      (CONTINUED)

                      Interest income is not reported when full loan repayment
                      is doubtful, typically when the loan is impaired or
                      payments are past due over 90 days. Payments received on
                      such loans are reported as principal reductions.

                      A loan is impaired when full payment under the loan terms
                      is not expected. Impairment is evaluated in total for
                      smaller-balance loans of similar nature such as
                      residential mortgage, consumer, and credit card loans, and
                      on an individual loan basis for other loans. If a loan is
                      impaired, a portion of the allowance is allocated so that
                      the loan is reported, net, at the present value of
                      estimated future cash flows using the loan's existing rate
                      or at the fair value of collateral if repayment is
                      expected solely from the collateral.

                  2.  POTENTIAL PROBLEM LOANS

                      The Company had no potential problem loans as of December
                      31, 1999 which have not been disclosed in Table C 1., but
                      where known information about possible credit problems of
                      borrowers causes management to have serious doubts as to
                      the ability of such borrowers to comply with the present
                      loan repayment terms and which may result in disclosure of
                      such loans into one of the problem loan categories.

                  3.  FOREIGN OUTSTANDING

                      Not applicable.

                  4.  LOAN CONCENTRATIONS

                      Refer to Page 47, Note 11 of the Annual Report To
                      Shareholders.

                  D.  OTHER INTEREST-BEARING ASSETS

                      Not applicable.


         IV SUMMARY OF LOAN LOSS EXPERIENCE

                      For additional explanation of factors which influence
                      management's judgment in determining amounts charged to
                      expense, refer to Page 19, "Management Discussion and
                      Analysis" and Pages 36 - 37, Note 1 of the Annual Report
                      To Shareholders.




                                       7



<PAGE>   8



                         UNITED BANCORP, INC. FORM 10-K



ITEM 1   DESCRIPTION OF BUSINESS (CONTINUED)

         IV SUMMARY OF LOAN LOSS EXPERIENCE (CONTINUED)

              A   ANALYSIS OF THE ALLOWANCE FOR LOAN LOSSES

                  The following schedule presents an analysis of the allowance
                  for loan losses, average loan data and related ratios for the
                  years ended December 31, 1999, 1998, 1997, 1996 and 1995:


<TABLE>
<CAPTION>

                         (In thousands)                1999           1998          1997           1996           1995
                                                   -------------  ------------- -------------- -------------- -------------
<S>                                                <C>            <C>           <C>            <C>            <C>
               LOANS
               Loans outstanding                      $ 180,516      $ 164,221      $ 171,477      $ 166,516      $157,369
               Average loans outstanding              $ 168,868      $ 168,626      $ 169,066      $ 160,409      $150,429


                         (In thousands)
               ALLOWANCE FOR LOAN LOSSES

               Balance at beginning of year           $   3,033      $   3,039      $   2,756      $   2,593     $   1,693
               Loan charge-offs:
                    Commercial                               85            139            125            467            69
                    Commercial real estate                   30              -              -              -             -
                    Real estate                              21             51             20             40             9
                    Installment                             807            861            661            583           308
                                                   -------------  ------------- -------------- -------------- -------------
               Total loan charge-offs                       943          1,051            806          1,090           386
                                                   -------------  ------------- -------------- -------------- -------------


               Loan recoveries
                    Commercial                               50             87             32             13             6
                    Commercial real estate                   12                             -              -             -
                    Real estate                               3              9              3              5             1
                    Installment                             228            151            122             70            75
                                                   -------------  ------------- -------------- -------------- -------------
               Total loan recoveries                        293            247            157             88            82
                                                   -------------  ------------- -------------- -------------- -------------

               Net loan charge-offs                         650            804            649          1,002           304

               Provision for loan losses                    727            798            932          1,165         1,204
                                                   -------------  ------------- -------------- -------------- -------------

               Balance at end of year                 $   3,110      $   3,033      $   3,039      $   2,756     $   2,593
                                                   =============  ============= ============== ============== =============

               Ratio of net charge-offs to average
                 loans outstanding for the year           0.38%          0.48%          0.38%          0.62%         0.20%
                                                   =============  ============= ============== ============== =============
</TABLE>




                                       8



<PAGE>   9




                         UNITED BANCORP, INC. FORM 10-K


ITEM 1   DESCRIPTION OF BUSINESS (CONTINUED)

         IV SUMMARY OF LOAN LOSS EXPERIENCE (CONTINUED)

                B     ALLOCATION OF THE ALLOWANCE FOR LOAN LOSSES

                      The following table allocates the allowance for possible
                      loan losses at December 31, 1999, 1998, 1997, 1996 and
                      1995. The allowance has been allocated according to the
                      amount deemed to be reasonably necessary to provide for
                      the probability of losses being incurred within the
                      following categories of loans at the dates indicated:
<TABLE>
<CAPTION>
<S><C>
                                                      1999                                                    1998
                                           ---------------------------                             --------------------------
                                                         % OF LOANS                                              % OF LOANS
                     (In thousands)        ALLOWANCE      TO TOTAL            (In thousands)        ALLOWANCE     TO TOTAL
               Loan type                     AMOUNT         LOANS       Loan type                    AMOUNT        LOANS
                                           -----------  --------------                             ------------ -------------

                   Commercial                 $   195           8.57%       Commercial                 $   215         7.87%
                   Commercial real estate         439          33.40%       Commercial real estate         432        33.00%
                   Real estate                    343          28.45%       Real estate                    567        30.10%
                   Installment                    620          29.58%       Installment                    818        29.03%
                   Unallocated                  1,413             N/A       Unallocated                  1,001           N/A
                                           -----------  --------------                             ------------ -------------
                    Total                     $ 3,010         100.00%        Total                     $ 3,033       100.00%
                                           ===========  ==============                             ============ =============

                                                     1997                                                     1996
                                           ---------------------------                             --------------------------
                                                         % OF LOANS                                              % OF LOANS
                     (In thousands)        ALLOWANCE      TO TOTAL            (In thousands)        ALLOWANCE     TO TOTAL
               Loan type                     AMOUNT         LOANS       Loan type                    AMOUNT        LOANS
                                           -----------  --------------                             ------------ -------------

                   Commercial                 $   403           9.70%       Commercial                 $   320         9.05%
                   Commercial real estate         322          28.69%       Commercial real estate         292        24.96%
                   Real estate                    606          29.07%       Real estate                    601        31.80%
                   Installment                  1,200          32.54%       Installment                    841        34.19%
                   Unallocated                    508             N/A       Unallocated                    702           N/A
                                           -----------  --------------                             ------------ -------------
                    Total                     $ 3,039         100.00%        Total                     $ 2,756       100.00%
                                           ===========  ==============                             ============ =============


                                                     1995
                                           ---------------------------
                                                         % OF LOANS
                     (In thousands)        ALLOWANCE      TO TOTAL
               Loan type                     AMOUNT         LOANS
                                           -----------  --------------

                   Commercial                 $   551           8.65%
                   Commercial real estate         348          22.83%
                   Real estate                    416          32.43%
                   Installment                    694          36.09%
                   Unallocated                    584             N/A
                                           -----------  --------------
                    Total                     $ 2,593         100.00%
                                           ===========  ==============

</TABLE>





                                       9



<PAGE>   10


                         UNITED BANCORP, INC. FORM 10-K


ITEM 1   DESCRIPTION OF BUSINESS (CONTINUED)

                V     DEPOSITS

                  A   SCHEDULE OF AVERAGE DEPOSIT AMOUNTS AND RATES
<TABLE>
<CAPTION>
<S>                              <C>
                         (1)      Refer to Page 27 of the Annual Report To Shareholders.
                         (2)      Refer to Page 27 of the Annual Report To Shareholders.
                         (3)      Refer to Page 27 of the Annual Report To Shareholders.
                         (4)      Refer to Page 27 of the Annual Report To Shareholders.
                         (5) -(8) Not applicable.
</TABLE>

                  B   OTHER CATEGORIES

                      Not applicable.

                  C   FOREIGN DEPOSITS

                      Not applicable.

                  D   MATURITY ANALYSIS OF TIME DEPOSITS GREATER THAN $100,000.

                      The following schedule details the maturities of time
                      certificates of deposit in amounts of $100,000 or more for
                      the year ended December 31, 1999:
<TABLE>
<CAPTION>
<S>                                         <C>
         (In thousands)
Three months or less                       $  4,738
Over three through six months                 2,791
Over six through twelve months                7,217
Over twelve months                            8,584
                                  ------------------
  Total                                    $ 23,330
                                  ==================
</TABLE>


                  E   TIME DEPOSITS GREATER THAN $100,000 ISSUED BY FOREIGN
                      OFFICES.

                      Not applicable.

                 VI   RETURN ON EQUITY AND ASSETS

                      The ratio of net income to daily average total assets and
                      average shareholders' equity, and certain other ratios,
                      were as follows:
<TABLE>
<CAPTION>
                                                                     DECEMBER 31,
                                                   --------------------------------------------
                                                       1999           1998           1997
                                                   -------------  -------------- --------------
Percentage of net income to:
<S>                                               <C>             <C>            <C>
     Average total assets                                 1.09%           1.17%          1.10%
     Average shareholders' equity                        11.94%          11.80%         11.48%
Percentage of dividends declared per common
  share to net income per common share - basic           46.73%          41.77%         36.38%
Percentage of average shareholders' equity
  to average total assets                                 9.14%           9.83%          9.55%
</TABLE>




                                     10



<PAGE>   11





                         UNITED BANCORP, INC. FORM 10-K

ITEM 1   DESCRIPTION OF BUSINESS (CONTINUED)

         VII    SHORT-TERM BORROWINGS

                  Information concerning securities sold under agreements to
                  repurchase is summarized as follows:

<TABLE>
<CAPTION>

                                    (In thousands)                         1999            1998           1997
                                                                    --------------  -------------- --------------
<S>                                                                 <C>             <C>            <C>
                    Balance at December 31,                            $   5,788     $      7,733    $     8,391
                    Weighted average interest rate at December 31,           3.80%           4.44%          4.90%
                    Average daily balance during the year              $    7,306    $      7,817    $     8,211
                    Average interest rate during the year                    4.30%           4.66%          4.81%
                    Maximum month-end balance during the year          $    8,506    $      9,109    $     9,316
</TABLE>




                  Securities sold under agreements to repurchase are financing
                  arrangements whereby the Company sells securities and agrees
                  to repurchase the identical securities at the maturities of
                  the agreements at specified prices

                  Information concerning the cash management line of credit from
                  the Federal Home Loan Bank of Cincinnati, Ohio is summarized
                  as follows:
<TABLE>
<CAPTION>
                                  (In thousands)                      1999            1998           1997
                                                                  --------------  -------------- --------------
<S>                                                               <C>             <C>            <C>
                  Balance at December 31,                           $     19,145    $      9,175   $          -
                  Weighted average interest rate at December 31,            4.75%           5.02%             -
                  Average daily balance during the year             $      9,363    $      2,085   $        608
                  Average interest rate during the year                     5.55%           5.95%          6.06%
                  Maximum month-end balance during the year         $     22,028    $      9,175   $      1,845
</TABLE>



                  No other individual component of the borrowed funds total
                  comprised more than 30% of shareholders' equity and
                  accordingly are not disclosed in detail.

ITEM 2   PROPERTIES

         Refer to Pages 9 - 11, "Corporate Profile" in the Annual Report To
         Shareholders. Management considers the properties described on Pages 9
         - 11 of the Annual Report are in good operating condition for the
         purpose for which it is used. The properties are unencumbered by any
         mortgage or security interest and is, in management's opinion,
         adequately insured.

ITEM 3   LEGAL PROCEEDINGS

         Refer to Page 47, Note 10 of the Annual Report To Shareholders.

ITEM 4   SUBMISSION OF MATTERS TO A VOTE OF SECURITY HOLDERS

         No motions were submitted to shareholders for a vote during the fourth
         quarter of 1999.

PART II

ITEM 5   MARKET FOR REGISTRANT'S COMMON EQUITY AND RELATED SHAREHOLDER MATTERS

         Refer to Page 16, "Shareholder Information" of the Annual Report To
         Shareholders.

ITEM 6   SELECTED FINANCIAL DATA

         Refer to inside back cover, "Five Year Performance Summary" of the
         Annual Report To Shareholders.



                                       11


<PAGE>   12



                         UNITED BANCORP, INC. FORM 10-K



ITEM 7   MANAGEMENT'S DISCUSSION AND ANALYSIS OF FINANCIAL CONDITION AND
         RESULTS OF OPERATIONS

         Refer to Pages 17 - 30, "Management's Discussion and Analysis" of the
         Annual Report To Shareholders.

ITEM 7A  QUANTITATIVE AND QUALITATIVE DISCLOSURES ABOUT MARKET RISK

         Refer to Pages 23 - 25, "Asset/Liability Management and Sensitivity to
         Market Risks" of the Annual Report To Shareholders.

ITEM 8   FINANCIAL STATEMENTS AND SUPPLEMENTARY DATA

         Refer to Pages 26 and 31 - 52 of the Annual Report To Shareholders.

ITEM 9   CHANGES IN AND DISAGREEMENTS WITH ACCOUNTANTS

         There were no changes in or disagreements with accountants.













                                       12




<PAGE>   13



                         UNITED BANCORP, INC. FORM 10-K


PART III

ITEM 10  DIRECTORS AND EXECUTIVE OFFICERS OF THE REGISTRANT

         (a)      Refer to Pages 4 - 8 of the Proxy Statement.
         (b)      Executive Officers of the Registrant:
<TABLE>
<CAPTION>

<S>                                                  <C>      <C>
                    James W. Everson                   61       Chairman, President and Chief Executive Officer

                    Alan M.  Hooker                    49       Executive Vice President - Administration

                    Norman F. Assenza, Jr.             54       Vice President - Operations and Secretary

                    Randall M. Greenwood               36       Vice President - Chief Financial Officer, Treasurer

                    James A. Lodes                     54       Vice President - Lending
</TABLE>


         (1)      Each individual has held the position noted during the past
                  five years, except for the following:

                  Randall M. Greenwood served as a Business Assurance Manager of
                  Coopers and Lybrand LLP of Columbus, Ohio from 1993 to
                  November of 1997. He served as a Manager for BankOne
                  Corporation in Columbus, Ohio from February 1991 to August
                  1993 and as a Supervisor at Coopers and Lybrand LLP in
                  Columbus, Ohio from September 1986 through February 1991. He
                  has served as Vice President - Chief Financial Officer of
                  United Bancorp, Inc. and as Senior Vice President - Chief
                  Financial Officer of The Citizens Savings Bank, Martins Ferry,
                  Ohio since December 1997.

                  Alan M. Hooker served as President of Fairfield National
                  Division of the Park National Bank where he also served on
                  their Advisory Board. He has held senior level banking
                  positions with financial institutions in Washington, D.C., and
                  Baltimore, Maryland. He has served as President and Chief
                  Executive Officer of The Community Bank, Glouster, Ohio and as
                  Executive Vice President Administration of United Bancorp,
                  Inc. since October 26, 1998.

ITEM 11           EXECUTIVE COMPENSATION

                  Refer to Pages 10 - 15 of the Proxy Statement.

ITEM 12           SECURITY OWNERSHIP OF CERTAIN BENEFICIAL OWNERS AND MANAGEMENT

                  Refer to Pages 4 - 8 of the Proxy Statement.

ITEM 13           CERTAIN RELATIONSHIPS AND RELATED TRANSACTIONS

                  Refer to Page 15 of the Proxy Statement.






                                       13



<PAGE>   14


                         UNITED BANCORP, INC. FORM 10-K


PART IV

ITEM 14           EXHIBITS, FINANCIAL STATEMENTS, SCHEDULES AND REPORTS ON FORM
                  8-K

         (a)      DOCUMENTS FILED AS PART OF FORM 10-K

                  1.       The following consolidated financial statements
                           appear in the 1999 Annual Report To Shareholders and
                           are incorporated by reference:
<TABLE>
<CAPTION>
<S>                                                                                             <C>       <C>
                           Report of Independent Auditors                                          Page     31
                           Consolidated Balance Sheets                                             Page     32
                           Consolidated Statements of Income                                       Page     33
                           Consolidated Statements of Shareholders' Equity                         Page     34
                           Consolidated Statements of Cash Flow                                    Page     35
                           Notes to the Consolidated Financial Statements                          Pages    36 - 52
</TABLE>

                  2.       The summary of selected quarterly results of
                           operations appears on Page 26 in the 1999 Annual
                           Report To Shareholders and is incorporated by
                           reference.

                  3.       Exhibits

                           2        Not Applicable
                           3(i)(ii) Articles of Incorporation of United
                                    Bancorp, Inc. including amendments and By
                                    Laws, previously filed with the Securities
                                    and Exchange Commission on November 16,
                                    1983.
                           4        Not applicable.
                           9        Not applicable.
                           10       Reference to special severance agreement on
                                    Page 14 of the Proxy Statement
                           11       Statement regarding computation of per share
                                    earnings (included in Note 1 to the
                                    consolidated financial statements on page 38
                                    and Note 16 on Page 52 of the Annual Report
                                    To Shareholders.)
                           12       Not applicable.
                           13       Reference to the Annual Report To
                                    Shareholders for the fiscal year ended
                                    December 31, 1999.
                           16       Not applicable.
                           18       Not applicable.
                           21.1     Reference to The Citizens Savings Bank,
                                    Martins Ferry, Ohio, incorporated on
                                    December 31, 1902, previously filed with the
                                    Securities and Exchange Commission..
                           21.2     Reference to The Community Bank, Lancaster,
                                    Ohio, incorporated on August 1, 1949,
                                    previously filed with the Securities and
                                    Exchange Commission.
                           22       Not applicable.
                           23       Consents of Experts and Council.
                           24       Not applicable.
                           27       Financial Data Schedule
                           99       Not applicable.

         (b)      The Company filed no reports on SEC Form 8-K during the last
                  quarter of the period covered by this report.



                                       14






<PAGE>   15



                         UNITED BANCORP, INC. FORM 10-K


                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.

                (Registrant) United Bancorp, Inc.
<TABLE>
<CAPTION>

<S>                      <C>                                                         <C>
                By:      /s/ James W. Everson                                           March 24, 2000
                         -------------------------------------
                         James W. Everson, Chairman, President & CEO



                By:      /s/ Randall M. Greenwood                                       March 24, 2000
                         -------------------------------------
                         Randall M. Greenwood, CFO



                By:      /s/ Michael J. Arciello                                        March 24, 2000
                         -------------------------------------
                         Michael J. Arciello



                By:      /s/ John H. Clark, Jr.                                         March 24, 2000
                         -------------------------------------
                         John H. Clark, Jr.



                By:      /s/ John M. Hoopingarner                                       March 24, 2000
                         -------------------------------------
                         John M. Hoopingarner



                By:      /s/ Richard L. Riesbeck                                        March 24, 2000
                         -------------------------------------
                         Richard L. Riesbeck


                         /s/ L.E. Richardson, Jr.
                By:      -------------------------------------                          March 24, 2000
                         L.E. Richardson, Jr.



                By:      /s/ Matthew C. Thomas                                          March 24, 2000
                         -------------------------------------
                         Matthew C. Thomas
</TABLE>



                                       15
<PAGE>   16



                         UNITED BANCORP, INC. FORM 10-K


EXHIBIT INDEX

         Exhibit No.       Description                           SK Item 601 No.
         -----------       -----------                           ---------------

                1          Financial Data Schedule               27

                2          Annual Report to Shareholders         13

                3          Consents of Experts and Council       23








                                       16