<PAGE>   1



--------------------------------------------------------------------------------




                       SECURITIES AND EXCHANGE COMMISSION
                             Washington, D.C. 20549



                                   FORM 8-K/A

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


      Date of Report (Date of earliest event reported): September 14, 1998

                               MCI WORLDCOM, INC.
             (Exact Name of Registrant as Specified in its Charter)


   Georgia                            0-11258                  58-1521612
(State or Other                   (Commission File            (IRS Employer
Jurisdiction of                       Number)             Identification Number)
 Incorporation)


                              515 East Amite Street
                         Jackson, Mississippi 39201-2702
                     (Address of Principal Executive Office)


       Registrant's telephone number, including area code: (601) 360-8600



                                 WORLDCOM, INC.
                   -------------------------------------------
                   (Former name, if changed since last report)




--------------------------------------------------------------------------------



<PAGE>   2




ITEM 7.  FINANCIAL STATEMENTS AND EXHIBITS

(a)      Financial statements of businesses acquired

         The audited financial statements as of December 31, 1997 and 1996 and
         for each of the three years in the period ended December 31, 1997 of
         MCI, including the report of independent auditors, were previously
         reported in WorldCom's Current Report on Form 8-K/A-3 dated November 9,
         1997 (filed May 28, 1998).

         The unaudited financial statements of MCI as of and for the six months
         ended June 30, 1998 and 1997 were previously reported in MCI WorldCom's
         Current Report on Form 8-K dated September 14, 1998 (filed September
         29, 1998).

(b)      Pro forma financial information

         Pursuant to paragraph (a)(4) of Item 7 of Form 8-K, the Company hereby
         files the pro forma financial information listed in the Index on page
         F-1 herein and incorporated by reference herein.

(c)      Exhibits

         See Exhibit Index



<PAGE>   3





                                    SIGNATURE

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


Dated:  November 16, 1998


                                       MCI WORLDCOM, INC.



                                       By: /s/ Scott D. Sullivan
                                          ----------------------------------
                                          Scott D. Sullivan
                                          Chief Financial Officer



<PAGE>   4







               INDEX TO FINANCIAL STATEMENTS AND OTHER INFORMATION

          Financial Statements                                     Page Numbers
          --------------------                                     ------------


Pro Forma Condensed Combined Financial Statements                      F-2
Pro Forma Condensed Combined Balance Sheet as of June 30, 1998         F-4
Pro Forma Condensed Combined Statement of Operations for the
   six months ended June 30, 1998                                      F-5
Pro Forma Condensed Combined Statement of Operations for the
   year ended December 31, 1997                                        F-6
Notes to Pro Forma Condensed Combined Financial Statements             F-7



<PAGE>   5



                PRO FORMA CONDENSED COMBINED FINANCIAL STATEMENTS


References herein to the "Company" or "MCI WorldCom" refer to MCI WORLDCOM,
Inc., a Georgia corporation, and its subsidiaries, which prior to September 15,
1998, was named WorldCom, Inc. ("WorldCom").

On September 14, 1998, the Company acquired MCI Communications Corporation, a
Delaware corporation ("MCI"), pursuant to the merger (the "MCI Merger") of MCI
with and into TC Investments Corp. ("Acquisition Subsidiary"), a wholly owned
subsidiary of the Company. Upon consummation of the MCI Merger, Acquisition
Subsidiary was renamed MCI Communications Corporation which became a wholly
owned subsidiary of the Company.

As a result of the MCI Merger, each share of MCI common stock was converted into
the right to receive 1.2439 shares of MCI WorldCom common stock, par value $.01
per share (the "Common Stock" or "MCI WorldCom Common Stock"), or approximately
755 million MCI WorldCom common shares in the aggregate, and each share of MCI
Class A common stock outstanding (all of which were held by British
Telecommunications plc ("BT")) was converted into the right to receive $51.00 in
cash or approximately $7 billion in the aggregate. The funds paid to BT were
obtained by the Company from (i) available cash as a result of the Company's
$6.1 billion public debt offering in August 1998; (ii) the sale of MCI's
Internet backbone facilities and wholesale and retail Internet business (the
"iMCI Business") to Cable and Wireless plc ("Cable & Wireless") for $1.75
billion in cash on September 14, 1998; (iii) the sale of MCI's 24.9% equity
stake in Concert Communications Services ("Concert") to BT for $1 billion in
cash on September 14, 1998; and (iv) availability under the Company's commercial
paper program and credit facilities.

Upon effectiveness of the MCI Merger, the then outstanding and unexercised
options exercisable for shares of MCI common stock were converted into options
exercisable for an aggregate of approximately 83 million shares of MCI WorldCom
Common Stock having the same terms and conditions as the MCI options, except
that the exercise price and the number of shares issuable upon exercise were
divided and multiplied, respectively, by 1.2439. The MCI Merger was accounted
for as a purchase.

The following unaudited Pro Forma Condensed Combined Balance Sheet as of June
30, 1998 and unaudited Pro Forma Condensed Combined Statements of Operations for
the six months ended June 30, 1998, and for the year ended December 31, 1997,
illustrate the effect of the MCI Merger as if the MCI Merger had occurred on
June 30, 1998, for the Pro Forma Condensed Combined Balance Sheet and as of the
earliest date presented for the Pro Forma Condensed Combined Statement of
Operations. No adjustment has been included in the pro forma amounts for any
anticipated cost savings or other synergies.

                                      F-2

<PAGE>   6



          PRO FORMA CONDENSED COMBINED FINANCIAL STATEMENTS (CONTINUED)


These Pro Forma Condensed Combined Financial Statements should be read in
conjunction with the historical financial statements of WorldCom and MCI. The
historical financial statements of WorldCom and related notes as of December 31,
1997 and for each of the years in the three-year period ended December 31, 1997
are contained in WorldCom's Current Report on Form 8-K dated May 28, 1998 (filed
May 28, 1998) and the historical financial statements of WorldCom and related
notes as of June 30, 1998 and for the six months ended June 30, 1998 and 1997
are contained in WorldCom's Quarterly Report on Form 10-Q for the six months
ended June 30, 1998, which reports are incorporated by reference herein. The
historical financial statements of MCI and related notes as of December 31, 1997
and for each of the years in the three-year period ended December 31, 1997 are
contained in WorldCom's Current Report on Form 8-K/3 dated November 9, 1997
(filed May 28, 1998) and the historical financial statements of MCI and related
notes as of June 30, 1998 for the six months ended June 30, 1998 and 1997 are
contained in MCI WorldCom's Current Report on Form 8-K dated September 14, 1998
(filed September 29, 1998), which reports are incorporated by reference herein.

The Pro Forma Condensed Combined Financial Statements are presented for
comparative purposes only and are not intended to be indicative of actual
results had the transactions occurred as of the dates indicated above nor do
they purport to indicate results which may be attained in the future.

                                      F-3

<PAGE>   7



                 PRO FORMA CONDENSED COMBINED BALANCE SHEET(1)
                               AS OF JUNE 30, 1998
                                  (IN MILLIONS)


<TABLE>
<CAPTION>
                                                                                                                      MCI WorldCom
                                                               WorldCom          MCI               Pro Forma           Pro Forma
                                                            Historical(2)     Historical(2)       Adjustments          Combined
                                                            --------------   --------------       -----------          --------

<S>                                                           <C>               <C>               <C>                 <C>       
Current assets                                                $  2,394          $  5,434          $     --            $    7,828
Property, plant and equipment, net                               8,538            14,140            (3,400)(3)            19,278
Goodwill and other intangibles, net                             14,824             2,308            28,712 (3)            42,744
                                                                                                    (3,100)(3)(8)
Other assets                                                     1,326             4,104               (86)(5)             5,344
                                                              --------          --------          --------            ----------
                Total assets                                  $ 27,082          $ 25,986          $ 22,126            $   75,194
                                                              ========          ========          ========            ==========

Current liabilities                                           $  2,492          $  6,943          $     --            $    9,435
Long-term debt                                                   8,971             3,938             6,936 (3)(4)         19,845
Other liabilities                                                  500             2,167            (1,500)(3)             1,167
Mandatorily redeemable preferred stock                              --               750                --                   750
Shareholders' equity:
  Class A common stock                                              --                14               (14)(5)                --
  Common stock                                                      11                60               (60)(5)                19
                                                                                                         8 (6)
  Paid in capital                                               17,061             6,489            (6,489)(5)            49,117
                                                                                                    32,056 (6)
  Retained earnings (deficit)                                   (1,968)            5,623            (5,623)(5)            (5,068)
                                                                                                    (3,100)(3)(8)
  Other                                                             15                 2                (2)(5)               (71)
                                                                                                       (86)(5)
                                                              --------          --------          --------            ----------
                 Total shareholders' equity                     15,119            12,188            16,690                43,997
                                                              --------          --------          --------            ----------
                 Total liabilities and shareholders' equity   $ 27,082          $ 25,986          $ 22,126            $   75,194
                                                              ========          ========          ========            ==========
</TABLE>


The accompanying notes are an integral part of this statement.

                                      F-4

<PAGE>   8



            PRO FORMA CONDENSED COMBINED STATEMENT OF OPERATIONS(1)
                     FOR THE SIX MONTHS ENDED JUNE 30, 1998
                      (IN MILLIONS, EXCEPT PER SHARE DATA)


<TABLE>
<CAPTION>
                                                                                                           MCI WorldCom
                                                     WorldCom         MCI               Pro Forma           Pro Forma
                                                   Historical(2)  Historical(2)        Adjustments          Combined
                                                   -------------  -------------        -----------          --------

<S>                                                  <C>           <C>                <C>                  <C>       
Revenues                                             $   4,960     $   10,658         $     (968)(7)       $   14,650
Operating expenses:
    Line costs                                           2,407          5,722               (968)(7)            7,161
    Selling, general and administrative                  1,002          3,058                 --                4,060
    Depreciation and amortization                          630          1,311                390 (9)            2,036
                                                                                            (295)(10)
    In-process research and development and other
      charges                                              498             --              3,100 (8)            3,598
                                                     ---------     ----------         ----------           ----------
Operating income                                           423            567             (3,195)              (2,205)
Other income (expense):
    Interest expense                                      (210)          (106)              (244)(11)            (560)
    Other                                                   22             46                 --                   68
                                                     ---------     ----------         ----------           ----------
Income (loss) before income taxes and extraordinary
  item                                                     235            507             (3,439)              (2,697)
Provision for income taxes                                 288            181                 19 (12)             488
                                                     ---------     ----------         ----------           ----------
Income (loss) from continuing operations                   (53)           326             (3,458)              (3,185)
Preferred dividend requirements                             13             30                 --                   43
                                                     ---------     ----------         ----------           ----------
Net income (loss) applicable to common shareholders  $     (66)    $      296         $   (3,458)          $   (3,228)
                                                     =========     ==========         ==========           ==========

Number of shares issued
  and outstanding:
     Basic                                               1,028            722                                   1,757
                                                     =========     ==========                              ==========
     Diluted                                             1,028            737                                   1,757
                                                     =========     ==========                              ==========

Earnings (loss) per share(13)
     Basic                                           $   (0.06)    $     0.41                              $    (1.84)
                                                     =========     ==========                              ==========
     Diluted                                         $   (0.06)    $     0.40                              $    (1.84)
                                                     =========     ==========                              ==========
</TABLE>


The accompanying notes are an integral part of this statement.

                                      F-5

<PAGE>   9



                PRO FORMA CONDENSED COMBINED STATEMENT OF OPERATIONS(1)
                      FOR THE YEAR ENDED DECEMBER 31, 1997
                      (IN MILLIONS, EXCEPT PER SHARE DATA)


<TABLE>
<CAPTION>
                                                                                                               MCI WorldCom
                                                        WorldCom            MCI                Pro Forma        Pro Forma
                                                      Historical(2)    Historical(2)          Adjustments       Combined
                                                      -------------    -------------          -----------       --------

<S>                                                    <C>               <C>                 <C>                 <C>      
Revenues                                               $    7,476        $    19,653         $  (1,356)(7)       $  25,773
Operating expenses:
    Line costs                                              3,857             10,956            (1,356)(7)          13,457
    Selling, general and administrative                     1,626              5,940                --               7,566
    Depreciation and amortization                             976              2,082               780 (9)           3,248
                                                                                                  (590)(10)
                                                       ----------        -----------         ---------           ---------
Operating income                                            1,017                675              (190)              1,502
Other income (expense):
    Interest expense                                         (395)              (235)             (488)(11)         (1,118)
    Other                                                      41               (141)               --                (100)
                                                       ----------        -----------         ---------           ---------
Income (loss) before income taxes                             663                299              (678)                284
Provision for income taxes                                    416                 90                38 (12)            544
                                                       ----------        -----------         ---------           ---------
Income (loss) from continuing operations                      247                209              (716)               (260)
Preferred dividend requirements                                26                 60                --                  86
                                                       ----------        -----------         ---------           ---------
Net income (loss) applicable to common shareholders    $      221        $       149         $    (716)          $    (346)
                                                       ==========        ===========         =========           ========= 


Number of shares issued
  and outstanding:
     Basic                                                    966                693                                 1,659
                                                       ==========        ===========                             ========= 
     Diluted                                                  997                707                                 1,659
                                                       ==========        ===========                             ========= 

Earnings (loss) per share(13)
     Basic                                             $     0.23        $      0.22                             $   (0.21)
                                                       ==========        ===========                             ========= 
     Diluted                                           $     0.22        $      0.21                             $   (0.21)
                                                       ==========        ===========                             ========= 
</TABLE>

The accompanying notes are an integral part of this statement.

                                      F-6

<PAGE>   10


                               NOTES TO PRO FORMA
                     CONDENSED COMBINED FINANCIAL STATEMENTS

1.   The unaudited pro forma financial data do not give effect to any potential
     cost savings or other synergies that could result from the MCI Merger. In
     connection with the MCI Merger, the Company allocated $3.1 billion of the
     purchase price to in-process research and development ("R&D") projects of
     MCI (See Note 8). The pro forma data are not necessarily indicative of the
     operating results or financial position that would have occurred had the
     MCI Merger been consummated at the dates indicated, nor necessarily
     indicative of future operating results or financial position.

2.   These columns represent historical results of operations and financial
     position.

3.   This adjustment reflects the excess of consideration over net assets
     acquired. The following is a calculation of the estimated excess of
     consideration over net assets acquired (in millions except per share data):

<TABLE>
<S>                                                                                            <C>       
            Total MCI WorldCom stock issued, options assumed and payment to
             MCI Class A Common Stockholder                                                    $   39,000
            Inducement fee and estimated transaction costs                                            500
                                                                                               ----------
            Total consideration                                                                    39,500
            Historical net book value of MCI assets acquired at June 30, 1998                     (12,188)
                                                                                               ----------
            Preliminary purchase accounting adjustments:                                           27,312
             Fair value adjustment of property, plant & equipment, net of deferred taxes            3,400
             Adjustment for sales of businesses, net of taxes                                      (1,500)
                                                                                               ----------
            Estimated excess of consideration over net assets acquired                             29,212
            Inducement fee and estimated transaction costs reflected in
             WorldCom historical                                                                     (500)
                                                                                               ----------
                                                                                               $   28,712
                                                                                               ==========
</TABLE>

     The following is a summary of the adjustment to goodwill and other
     intangibles:

<TABLE>
<S>                                                                                           <C>        
            Purchased in-process R&D                                                          $     3,100
            Developed technology                                                                    1,700
            Tradename                                                                               1,100
            Goodwill                                                                               23,312
                                                                                              -----------
                                                                                              $    29,212
                                                                                              ===========
</TABLE>

     Goodwill and tradename are amortized on a straight line basis over 40 years
     and developed technology is depreciated on a straight line basis over 10
     years.

4.   This adjustment represents additional borrowings of $6.9 billion for the
     purpose of financing the cash payment to the holder of the MCI Class A
     Common Stock. Estimated transaction costs of $500 million (which includes a
     $465 million inducement fee paid to BT) were paid in 1997 and are reflected
     in the WorldCom historical column (See Note 3).

5.   These adjustments represent the elimination of MCI's stockholders' equity
     accounts and investment in MCI WorldCom Common Stock.

6.   These adjustments represent the issuance of approximately 755 million
     shares of MCI WorldCom Common Stock in connection with the MCI Merger at an
     assumed MCI exchange ratio of 1.2439 shares of MCI WorldCom Common Stock
     for each share of MCI common stock outstanding.

7.   These adjustments eliminate the revenues and corresponding line costs
     attributable to the intercompany transactions between WorldCom and MCI, as
     well as the elimination of the iMCI Business. Additionally, this adjustment
     includes a classification change for inbound international settlements
     which are now being treated as an offset to line costs instead of revenues.
     Previously, both MCI and WorldCom classified post telephone and telegraph
     administration

                                      F-7

<PAGE>   11

     settlements on a gross basis with the outbound settlement reflected as line
     cost expense and the inbound settlement reflected as revenue. This change
     better reflects the way in which the business is operated because the
     Company actually settles in cash through a formal net settlement process
     that is inherent in the operating agreements with foreign carriers.

8.   In connection with the MCI Merger, the Company also allocated $3.1 billion
     of the purchase price to in-process research and development projects. The
     Company used professional appraisal consultants to assess and allocate
     values to the in-process research and development. This allocation
     represents the estimated fair value based on risk-adjusted future cash
     flows related to the incomplete projects. At the date of the MCI Merger,
     the development of these projects had not yet reached technological
     feasibility and the R&D in progress had no alternative future uses.
     Accordingly, these costs were expensed as of the merger date.

     Discounting the net cash flows back to their present value is based on the
     weighted average cost of capital ("WACC"). The respective business
     enterprises are comprised of various types of assets, each possessing
     different degrees of investment risk contributing to the Company's overall
     WACC. Intangible assets are assessed higher risk factors due to their lack
     of liquidity and poor versatility for redeployment elsewhere in the
     business. In the MCI analysis, the implied WACC was 14% based on the
     purchase price paid, assumed liabilities, projected cash flows, and MCI's
     asset mix. Returns on monetary and fixed assets were estimated based on
     prevailing interest rates. The process for quantifying intangible asset
     investment risk involved consideration of the uncertainty associated with
     realizing discernible cash flows over the life of the asset. A discount
     range of 15.5% to 19% was used for valuing the in-process research and
     development. These discount rates are higher than the WACC due to the
     inherent uncertainties surrounding the successful development of the
     purchased in-process research and development, the useful life of such
     technology, the profitability levels of such technology, and the
     uncertainty of technological advances that are unknown at this time.

     The value of the in-process research and development projects was adjusted
     to reflect the relative value and contribution of the acquired R&D. In
     doing so, consideration was given to the R&D's stage of completion, the
     complexity of the work completed to date, the difficulty of completing the
     remaining development, costs already incurred and the projected cost to
     complete the projects.

     The Company believes that the assumptions used in the forecasts were
     reasonable at the time of the respective business combination. No assurance
     can be given, however, that the underlying assumptions used to estimate
     expected project sales, development costs or profitability, or the events
     associated with such projects, will transpire as estimated. For these
     reasons, actual results may vary from the projected results.

     Management expects to continue supporting these R&D efforts and believes
     the Company has a reasonable chance of successfully completing the R&D
     programs. However, there is risk associated with the completion of the R&D
     projects and the Company cannot be assured that any will meet with either
     technological or commercial success.

     If none of these R&D projects is successfully developed, the sales and
     profitability of the Company may be adversely affected in future periods.
     The failure of any particular individual project in-process would not
     materially impact the Company's financial condition, results of operations
     or the attractiveness of the overall investment in MCI. Operating results
     are subject to uncertain market events and risks, which are beyond the
     Company's control, such as trends in technology, government regulations,
     market size and growth, and product introduction or other actions by
     competitors.

     The integration and consolidation of MCI requires substantial management
     and financial resources. While the Company believes the early results of
     these efforts are encouraging, the MCI Merger necessarily involve a number
     of significant risks, including potential difficulties in assimilating the
     technologies and services of MCI and in achieving the expected synergies
     and cost reduction.

     A description of the acquired in-process technology and the estimates made
     by the Company for the MCI Merger is set forth below.

                                      F-8

<PAGE>   12

     The in-process technology acquired in the MCI Merger consisted of seventy
     significant R&D projects grouped into six categories. The aggregate value
     assigned to MCI in-process research and development was $3.1 billion. These
     projects were all targeted at: (1) developing and deploying an all optical
     network, new architecture of the telephone system using Internet Protocol
     ("IP") and developing the systems and tools necessary to manage the voice
     and data traffic; (2) creating new products and services; and (3)
     developing certain information systems that may enhance the management of
     MCI WorldCom's products and service offerings.

     A brief description of the six categories of in-process research and
     development projects purchased in connection with the MCI Merger is set
     forth below:

     o   R&D related to an All Optical Network. These projects involve R&D
         related to the development of an all optical network. This structure is
         in contrast to current systems which employ a combination of optics and
         electronics. New technologies that are in development include: (a) an
         optical cross connect system for all optical packet transport and
         sub-second service restoration, (b) a wavelength channel plan for
         enabling multiple simultaneous transmission channels, (c) projects
         related to distortion elimination, and (d) next generation optical
         networking technologies related to the fiber infrastructure.
         Achievements to date include demonstration of limited-scope prototypes
         in the laboratory. Remaining efforts include: demonstration of the
         system on a large scale with commercial traffic, physics research in
         certain areas, development of algorithms to enable network management,
         and addressing technology issues related to switching. The amount of
         R&D costs to date for these projects total $7 million. Estimated costs
         to complete are $10 million, as follows: 15% during the last quarter of
         1998, 48% during the four quarters in 1999, 31% during the four
         quarters in 2000, and 6% during the four quarters in 2001. The
         completion of these projects will be difficult and the risk of these
         technologies not being completed is rated as medium to high. Failure to
         complete the R&D would cause the Company's future revenues and profits
         attributable to the R&D not to materialize as these projects would
         contribute to differentiating the Company from the competition in the
         future.

     o   R&D Related to Data Transmission Service / Other Transmission Efforts.
         The Company is currently working on a variety of significant efforts
         related to data management. These new technologies include: (a) new
         data services to satisfy new capacity requirements and Internet needs,
         (b) a next generation intelligent network to enable deployment of
         specific new telecommunications services across multiple networks, (c)
         a 16 wavelength bi-directional line amplifier to amplify optical
         signals, (d) multiservice and integrated access platforms and
         development of new methods for serving ISPs on the local services
         network, and (e) Andromeda, which is related to specific improvements
         to Internet operations. Achievements to date include methods for new
         high speed switching, multicasting, and offering a variety of service
         levels, as well as architectural design for next generation intelligent
         networks. Tasks to complete the new technologies include: engineering
         related to telephone system to utilize IP; solving scalability issues
         across the infrastructure; and conducting extensive testing of the
         technologies under development. To date $48 million has been expended
         to develop these R&D projects. Estimated costs to complete the projects
         are $132 million, as follows: 9% during the last quarter of 1998, 33%
         during the four quarters in 1999, 46% during the four quarters in 2000,
         and 12% during the four quarters in 2001. The completion of these
         projects will be difficult and the risk of not completing these
         projects can be characterized as medium to high. Failure to complete
         the R&D would cause the future revenues and profits attributable to the
         R&D not to materialize.

     o   Next Generation Tools. The Company's personnel are developing a
         variety of new tools that are being designed to achieve specific
         reliability and quality objectives related to the network. Important
         new development technologies in this category include: (a) reliability
         and quality engineering tools related to the reliability test and
         quality control, (b) network design development tools to enable
         end-to-end network design and modeling capabilities, (c) the Integrated
         Management Platform Advanced Communications Technology ("IMPACT")
         project to provide new network management for the networks, (d) the
         integrated test system to provide a new testing architecture for the
         Company's local, long distance, and international networks, and (e) an
         enhanced traffic system and security. Progress to date includes:
         definition of architectural components, partial development of software
         algorithms, and limited prototypes for tasks. Remaining efforts include
         completion of algorithms, prototype development, validation, testing,
         and development of support systems. To date $84 million has been spent
         on the R&D projects. Estimated costs to complete are $48 million, as
         follows: 22% during the last quarter

                                      F-9

<PAGE>   13

         of 1998, 46% during the four quarters in 1999, 23% during the four
         quarters in 2000, and 9% during the four quarters in 2001. There are
         significant risks of not being able complete the prototypes and there
         is also uncertainty in the timeliness of completion. The aggregate risk
         level for this category of R&D projects is considered medium to high.
         Project failure would result in the elimination of the Company's future
         revenues and profits attributable to the R&D.

     o   Specific New Customer Care Capabilities. These projects involve a
         series of efforts designed to provide customers with a suite of new
         services. This includes development of major technologies such as: (a)
         the virtual data delivery system to engineer new order processing and
         provisioning capabilities for data services, (b) network automation
         projects related to capacity and change management, (c) hyperlink to
         deploy private lines and frame relay circuits utilizing a new
         methodology, (d) common data platform to create a depository of network
         management information, and (e) the Talisman project to develop data
         products for the network MCI One Voice. Achievements to date include
         design, partial coding, and prototyping. Tasks to complete include:
         addition of significant features and functionality; additional design,
         testing and coding; and addressing scalability issues. To date $67
         million has been spent on developing this R&D. Estimated costs to
         complete are $76 million, as follows: 20% during the last quarter of
         1998, 50% during the four quarters in 1999, 19% during the four
         quarters in 2000, and 11% during the four quarters in 2001. There are
         significant risks in completing the algorithms successfully and on
         time. The aggregate risk level for this category of R&D projects is
         considered medium to high. Project failure would eliminate the
         Company's future revenues and profits attributable to the R&D.

     o   R&D Related to Local Services. This category involves a series of
         specific projects to create an offering of local services on a national
         basis. Efforts include: (a) electronic bonding for local service
         maintenance organizations, (b) elements of an order automation and
         tracking system, (c) access technology development, and (d) the
         substantial R&D related to the network optimization enhancement system.
         Achievements to date include: completion of system definitions, partial
         coding development, and base functionality developed on certain
         projects. Tasks to complete include adding features and functionality,
         module development and testing. To date $53 million has been spent on
         developing the R&D projects. Estimated costs to complete are $38
         million, as follows: 25% during the last quarter of 1998, 43% during
         the four quarters in 1999, 21% during the four quarters in 2000, and
         11% during the four quarters in 2001. There are significant risks
         related to developing the interfaces and the required technologies and
         the complex interconnections. The aggregate risk level for this
         category of R&D projects is considered medium to high. Failure of the
         R&D would eliminate the Company's future revenues and profits
         attributable to the R&D.

     o   New Products and Services. A series of new products and services are
         being developed by the Company. These include: (a) video services to
         design and implement a new terrestrial video distribution network for
         real-time quality video, (b) distance learning services via an
         integrated multimedia network platform, (c) fractal compression
         technology for image compression and encoding to reduce data transmit
         time and bit losses, and (d) integrated messaging for one number
         service for telephone, fax, voicemail, Internet, and paging. Progress
         to date includes: definition, development, and component testing;
         feasibility and analysis; and development of prototypes. Remaining
         development includes: design and deployment; resolving issues related
         to product functionality; and addressing scalability issues across the
         Company's infrastructure. To date $37 million has been spent on
         developing the R&D in this category. Estimated costs to complete are
         $38 million, as follows: 24% during the last quarter of 1998, 43%
         during the four quarters in 1999, 22% during the four quarters in 2000,
         and 11% during the four quarters in 2001. There are significant risks
         in completing the R&D projects, particularly developing the leading
         edge components, compression technologies, and developing operational
         support systems. The aggregate risk level for this category of R&D
         projects is considered medium to high. Project failure would eliminate
         the Company's future revenues and profits attributable to the R&D.

                                      F-10

\
<PAGE>   14

     A summary of allocated values by technology/project is as follows (in
     millions):

<TABLE>
<CAPTION>
                                                                  Developed        In-Process
                                                                  Technology           R&D
                                                                 -----------       -----------
<S>                                                              <C>               <C>        
               All Optical Network                               $       200       $       400
               Data Transmission Service/Other                           200               300
               Next Generation Tools                                     100               400
               New Customer Care Capabilities                            800             1,100
               Local                                                     200               700
               New Products and Services                                 200               200
                                                                 -----------       -----------
                                                                 $     1,700       $     3,100
                                                                 ===========       ===========
</TABLE>

     The value assigned to purchased in-process technology was determined by
     estimating the contribution of the purchased in-process technology to
     developing commercially viable products, estimating the resulting net cash
     flows from the expected product sales of such products, and discounting the
     net cash flows to their present value using a risk-adjusted discount rate.
     Royalty rates used in the valuation of in-process R&D ranged from 1% to 3%.
     Funding for such projects is expected to be obtained from internally
     generated sources.

     Developed technology will be depreciated over 10 years on a straight-line
     basis. The remaining purchase price included allocations to goodwill and
     tradename which will be amortized over 40 years on a straight-line basis.

     Total MCI stand-alone revenues are projected to exceed $34 billion within
     five years. This level of revenue implies a compound annual growth rate
     ("CAGR") of approximately 12.3%. Estimated total revenues from the acquired
     in-process technology peak in the year 2001 and steadily decline in 2002
     through 2009 as other new product and service technologies are expected to
     be introduced by the combined company. These projections are based on
     management's estimates of market size and growth, expected trends in
     technology, and the expected timing of new product introductions. These
     projections, which constitute forward-looking statements, were not made
     with a view to public disclosure and were based on a variety of estimates
     and judgments. Actual results may vary materially due to a number of
     significant risks, including, without limitation, uncertainties regarding
     future business, economic, competitive, regulatory and financial market
     conditions and future business decisions, all of which are difficult to
     predict and many of which are beyond the Company's control. No assurance
     can be given that such projections will be realized. The Company does not
     intend to update or supplement these projections in the future.

9.   This entry reflects the adjustment to amortization and depreciation for the
     effect of the excess of consideration over net assets acquired in the MCI
     Merger. Goodwill and tradename are amortized on a straight line basis over
     40 years while developed technology is depreciated on a straight line basis
     over 10 years (See Note 3).

10.  This entry reflects the adjustment to depreciation expense for the effect
     of the fair value adjustment of MCI's property, plant and equipment based
     on an evaluation of depreciated replacement cost (See Note 3).

11.  These adjustments represent the recognition of interest expense on the
     additional borrowings of WorldCom to finance the cash payment to the
     holder of the MCI Class A common stock and transaction costs (see Note 4).
     The interest expense was calculated based on WorldCom's incremental
     borrowing rate of 6.5%. A change of 1/8% in the incremental rate would
     affect interest expense by $4.7 million and $9.3 million for the six
     months ended June 30, 1998 and for the year ended December 31, 1997,
     respectively.

12.  These entries represent the tax effect of the pro forma adjustments.

13.  Pro forma per share data are based on the number of MCI WorldCom common
     and common equivalent shares that would have been outstanding had the MCI
     Merger occurred on the earliest date presented.

                                      F-11

<PAGE>   15




                                  EXHIBIT INDEX

<TABLE>
<CAPTION>
         Exhibit No.       Description of Exhibit
         -----------       ----------------------

<S>                        <C>
            2.1            Agreement and Plan of Merger by and among WorldCom, TC Investments Corp. and MCI dated as of November 9,
                           1997 (filed as Annex I to the Joint Proxy Statement/Prospectus dated January 22, 1998 included in
                           WorldCom's Registration Statement on Form S-4, Registration No. 333-36901 and incorporated herein by
                           reference)*

            2.2            Agreement by and among BT, MCI and WorldCom dated as of November 9, 1997 (incorporated herein by
                           reference to Exhibit 99.1 of WorldCom's Current Report on Form 8-K dated November 9, 1997 (filed November
                           12, 1997) (File No. 0-11258))*

            3.1            Second Amended and Restated Articles of Incorporation of MCI WORLDCOM, Inc. (including preferred stock
                           designations), as amended as of September 15, 1998 (incorporated herein by reference to Exhibit 4.1 of
                           MCI WorldCom's Post-Effective Amendment No. 1 on Form S-8 to Registration Statement on Form S-4, No.
                           333-36901 (filed September 14, 1998))

            3.2            Restated Bylaws of MCI WORLDCOM, Inc. (incorporated by reference to Exhibit 4.1 of MCI WorldCom's Current
                           Report on Form 8-K dated September 14, 1998 (filed September 29, 1998) (File No. 0-11258))*

           99.1            Certain portions of Press Release dated August 12, 1998 (incorporated herein by reference to Exhibit 99.1
                           to Current Report on Form 8-K dated September 14, 1998 (filed September 29, 1998) (File No. 0-11258)

           99.2            Joint Proxy Statement/Prospectus dated January 22, 1998 filed in connection with WorldCom's Registration
                           Statement on Form S-4, Registration No. 333-36901, and incorporated herein by reference.
</TABLE>








---------------------------------
  *      The registrant hereby undertakes to furnish supplementally a copy of
         any omitted schedule to this Agreement to the Securities and Exchange
         Commission upon request.