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                UNITED STATES SECURITIES AND EXCHANGE COMMISSION
                             WASHINGTON, D.C. 20549

                                    FORM 10-Q

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

FOR THE QUARTERLY PERIOD ENDED:  MARCH 31, 1999

                                               OR

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

FOR THE TRANSITION PERIOD FROM ____________ TO ______________

COMMISSION FILE NUMBER:  33-5539

                          CMC SECURITIES CORPORATION I
             (Exact name of Registrant as specified in its Charter)

                  NEVADA                                         75-2449544
    (State or other jurisdiction of                            (I.R.S. Employer
     incorporation or organization)                          Identification No.)

    2711 NORTH HASKELL, DALLAS, TEXAS                              75204
(Address of principal executive offices)                         (Zip Code)

        Registrant's telephone number, including area code (214) 874-2323

The Registrant meets the conditions set forth in General Instruction H(1)(a) and
(b) for Form 10-Q and is therefore filing this Form under the reduced disclosure
format.

Indicate by check mark whether the Registrant (1) has filed all documents and
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 [ ]

                      APPLICABLE ONLY TO CORPORATE ISSUERS:

Indicate the number of shares outstanding of each of the issuer's classes of
common stock, as of the last practicable date.

Common Stock ($1.00 par value)                          10,000 as of May 6, 1999

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<PAGE>   2


                          CMC SECURITIES CORPORATION I
                                    FORM 10-Q
                      FOR THE QUARTER ENDED MARCH 31, 1999


                                      INDEX



                        PART I. -- FINANCIAL INFORMATION

<TABLE>
<CAPTION>
                                                                               PAGE
                                                                               ----
<S>                                                                            <C>
ITEM 1. Financial Statements

   Balance Sheet -- March 31, 1999 and December 31, 1998.......................  1

   Statement of Operations -- Quarter Ended March 31, 1999 and 1998............  2

   Statement of Cash Flows -- Quarter Ended March 31, 1999 and 1998............  3

   Notes to Financial Statements...............................................  4

ITEM 2. Management's Discussion and Analysis of
        Financial Condition and Results of Operations..........................  6


                                 PART II. -- OTHER INFORMATION


ITEM 1. Legal Proceedings......................................................  7

ITEM 5. Other Information......................................................  7

ITEM 6. Exhibits and Reports on Form 8-K.......................................  7

SIGNATURES.....................................................................  8
</TABLE>


<PAGE>   3



                        PART I. -- FINANCIAL INFORMATION
                          CMC SECURITIES CORPORATION I
                                  BALANCE SHEET
                      (IN THOUSANDS, EXCEPT PER SHARE DATA)


ITEM 1. FINANCIAL STATEMENTS


<TABLE>
<CAPTION>
                                                       MARCH 31, 1999   DECEMBER 31, 1998
                                                       --------------    --------------
                                                         (UNAUDITED)
<S>                                                    <C>               <C>           
ASSETS
   Mortgage securities collateral                      $      333,006    $      380,790
                                                       ==============    ==============


LIABILITIES
   Collateralized mortgage securities                  $      333,006    $      380,790
   Accrued expenses                                                53                50
                                                       --------------    --------------

                                                              333,059           380,840
                                                       --------------    --------------


STOCKHOLDER'S DEFICIT
   Common stock - $1.00 par value,
     10 shares authorized, issued
     and outstanding                                               10                10
   Paid-in capital                                                 98                98
   Undistributed loss                                            (161)             (158)
                                                       --------------    --------------

                                                                  (53)              (50)
                                                       --------------    --------------

                                                       $      333,006    $      380,790
                                                       ==============    ==============
</TABLE>




See accompanying notes to financial statements.



                                      -1-
<PAGE>   4

                          CMC SECURITIES CORPORATION I
                             STATEMENT OF OPERATIONS
                                   (UNAUDITED)
                                 (IN THOUSANDS)



<TABLE>
<CAPTION>
                                                       QUARTER ENDED MARCH 31 
                                                      -------------------------
                                                         1999           1998 
                                                      ----------     ----------
<S>                                                   <C>            <C>       
Interest income on mortgage
   securities collateral                              $    6,448     $   10,186

Interest expense on collateralized
   mortgage securities                                     6,251          9,857
                                                      ----------     ----------

       Net interest income                                   197            329
                                                      ----------     ----------

Other expenses:
   Management fees                                             3              3
   Professional fees                                        --                7
   Pool insurance                                            197            329
                                                      ----------     ----------

     Total other expenses                                    200            339
                                                      ----------     ----------

Net loss                                              $       (3)    $      (10)
                                                      ==========     ==========
</TABLE>









See accompanying notes to financial statements.

                                       -2-
<PAGE>   5



                          CMC SECURITIES CORPORATION I
                             STATEMENT OF CASH FLOWS
                                   (UNAUDITED)
                                 (IN THOUSANDS)



<TABLE>
<CAPTION>
                                                          QUARTER ENDED MARCH 31
                                                         ------------------------
                                                            1999          1998 
                                                         ----------    ----------
<S>                                                      <C>           <C>        
OPERATING ACTIVITIES:
   Net loss                                              $       (3)   $      (10)
   Noncash item - amortization of discount
     and premium                                                (12)           (1)
   Net change in other assets and accrued expenses                3             3
                                                         ----------    ----------
       Net cash used by
         operating activities                                   (12)           (8)
                                                         ----------    ----------

INVESTING ACTIVITIES:
   Mortgage securities collateral:
     Principal collections on collateral                     47,449        30,659
     Decrease in accrued interest receivable                    286           190
     Decrease in short-term investments                           3             3
                                                         ----------    ----------
       Net cash provided by
         investing activities                                47,738        30,852
                                                         ----------    ----------

FINANCING ACTIVITIES:
   Collateralized mortgage securities:
     Principal payments on securities                       (47,449)      (30,659)
     Decrease in accrued interest payable                      (277)         (192)
   Capital contributions                                       --               7
                                                         ----------    ----------
       Net cash used by
         financing activities                               (47,726)      (30,844)
                                                         ----------    ----------

Net change in cash and cash equivalents                        --            --

Cash and cash equivalents at beginning
   of period                                                   --            --
                                                         ----------    ----------

Cash and cash equivalents at end of period               $     --      $     --
                                                         ==========    ==========
</TABLE>


See accompanying notes to financial statements.

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                          CMC SECURITIES CORPORATION I
                          NOTES TO FINANCIAL STATEMENTS
                                 MARCH 31, 1999
                                   (UNAUDITED)


NOTE A -- BASIS OF PRESENTATION

The accompanying unaudited financial statements have been prepared in accordance
with generally accepted accounting principles for interim financial information
and with the instructions to Form 10-Q and Rule 10-01 of Regulation S-X.
Accordingly, they do not include all of the information and footnotes required
by generally accepted accounting principles for complete financial statements.
In the opinion of management, all adjustments (consisting of normal recurring
accruals) considered necessary for a fair presentation have been included.
Operating results for the quarter ended March 31, 1999 are not necessarily
indicative of the results that may be expected for the calendar year ending
December 31, 1999. For further information refer to the financial statements and
footnotes thereto included in the CMC Securities Corporation I annual report on
Form 10-K for the year ended December 31, 1998.

NOTE B -- DISCLOSURES REGARDING FAIR VALUES OF MORTGAGE SECURITIES COLLATERAL

The estimated fair values of mortgage securities collateral have been determined
by using available market information and appropriate valuation methodologies;
however, considerable judgment is required in interpreting market data to
develop these estimates. In addition, fair values fluctuate on a daily basis.
Accordingly, the estimates presented herein are not necessarily indicative of
the amounts that could be realized in a current market exchange. The use of
different market assumptions and/or estimation methodologies may have a material
effect on the estimated fair value amounts.

The fair values of mortgage securities collateral were estimated using quoted
market prices, when available, including quotes made by Capstead Mortgage
Corporation's lenders in connection with designating collateral for repurchase
arrangements.

The following table summarizes the fair values of mortgage securities collateral
(in thousands):

<TABLE>
<CAPTION>
                                               MARCH 31, 1999    DECEMBER 31, 1998
                                               --------------    -----------------
<S>                                            <C>                <C>           
         Carrying amount                       $      333,006     $      380,790
         Unrealized gains                               6,271              7,893
         Unrealized losses                               (376)              --
                                               --------------     --------------

           Fair value                          $      338,901     $      388,683
                                               ==============     ==============
</TABLE>

All mortgage securities collateral is held-to-maturity. The maturity of mortgage
securities collateral is directly affected by the rate of principal prepayments
by mortgagors. In addition, upon the redemption of remaining bonds outstanding
pursuant to clean-up calls, released collateral may be sold. Such sales are
deemed maturities under the provisions of Statement of Financial Accounting
Standards No. 115. No such redemptions occurred during the three months ended
March 31, 1999 or during 1998.



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NOTE C -- NET INTEREST INCOME ANALYSIS

The following table summarizes interest income and interest expense and the
average effective interest rates for mortgage securities collateral and
collateralized mortgage securities (dollars in thousands):

<TABLE>
<CAPTION>
                                                    QUARTER ENDED MARCH 31     
                                      ---------------------------------------------------
                                              1999                         1998 
                                      ---------------------        ----------------------
                                                    AVERAGE                      AVERAGE
                                      AMOUNT         RATE          AMOUNT          RATE 
                                      ------        -------        ------        --------
<S>                                   <C>           <C>            <C>           <C>  
Interest income on mortgage
   securities collateral              $6,448         7.27%         $10,186       7.52%
Interest expense on
   collateralized mortgage
   securities                          6,251         7.05            9,857       7.28 
                                      ------                       -------

Net interest                          $  197                       $   329
                                      ======                       =======
</TABLE>

The following table summarizes the amount of change in interest income and
interest expense due to changes in interest rates versus changes in volume (in
thousands):

<TABLE>
<CAPTION>
                                              RATE*        VOLUME*        TOTAL 
                                           ----------    ----------    ----------
<S>                                        <C>           <C>           <C>        
Interest income on mortgage
   securities collateral                   $     (331)   $   (3,407)   $   (3,738)
Interest expense on
   collateralized mortgage
   securities                                    (300)       (3,306)       (3,606)
                                           ----------    ----------    ----------

                                           $      (31)   $     (101)   $     (132)
                                           ==========    ==========    ==========
</TABLE>

*    THE CHANGE IN INTEREST DUE TO BOTH VOLUME AND RATE HAS BEEN ALLOCATED TO
     VOLUME AND RATE CHANGES IN PROPORTION TO THE RELATIONSHIP OF THE ABSOLUTE
     DOLLAR AMOUNTS OF THE CHANGE IN EACH.

Interest payments on collateralized mortgage securities of $6,230,000 and
$9,639,000 were made during the quarters ended March 31, 1999 and 1998,
respectively.



                                      -5-
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ITEM 2.  MANAGEMENT'S DISCUSSION AND ANALYSIS OF FINANCIAL CONDITION AND
         RESULTS OF OPERATIONS


CMC Securities Corporation I (the "Company"), was incorporated in Nevada on May
7, 1986 as a special-purpose finance corporation and is a wholly-owned
subsidiary of Capstead Mortgage Corporation ("CMC").

As of November 30, 1993, the Company had issued 10 series of collateralized
mortgage obligations ("CMOs") with an aggregate original principal balance of
$1,727,627,000 under the registration statement. These issuances have been
accounted for as financings. The Company has essentially issued the maximum
amount of securities under the $1.732 billion amended registration statement
and, therefore, the Company has not issued any CMOs since November 30, 1993.
Since the Company did not retain any investment in the CMOs issued, no economic
benefit was or will be received, and therefore no net income or loss was or will
be recognized.

The Company's net losses are due to operational costs incurred (management and
professional fees).

LIQUIDITY AND CAPITAL RESOURCES

All ongoing cash CMO expenses of the Company are paid out of the excess cash
flows on the CMOs issued before the residual holders receive their residual
interest. The Company believes that the excess cash flows will be sufficient to
pay ongoing CMO expenses. Cash flow requirements due to ongoing operational
costs are funded by CMC.

IMPACT OF YEAR 2000

Many existing computer software programs use only two digits to identify the
year in date fields and, as such, could fail or create erroneous results by or
at the Year 2000. The Manager utilizes a number of software systems to
administer securitizations and otherwise manage the Company's affairs. In
addition, the Manager utilizes vendors in various capacities and interfaces with
various institutions. The Manager is exposed to the risk that its systems and
the systems of its vendors and institutions it interfaces with are not Year 2000
compliant.

     State of Readiness. The Manager has made and will continue to make
investments in its software systems and applications to ensure the Manager is
Year 2000 compliant. The Manager is also taking steps to ensure that the vendors
it utilizes and institutions that it interfaces with are also taking the
necessary steps to become Year 2000 compliant. This process is expected to be
essentially complete by the end of the second quarter of 1999.

     Costs. The financial costs of the Manager becoming Year 2000 compliant are
the responsibility of the Manager.

     Risks and Contingency Planning. Although the Manager expects that all its
systems and applications will be Year 2000 compliant per the above schedule and
well prior to December 31, 1999, there can be no assurance that all of the
vendors it utilizes and institutions that it interfaces with will complete their
compliance efforts. The Manager will continue to monitor their efforts in this
regard and will take all prudent steps necessary to ensure operations are not
disrupted including the use of other vendors or 




                                      -6-
<PAGE>   9

other methodologies and processes to transact the Company's business. The effect
of any disruption to the Company's operations of any such instances of
non-compliance is presently not determinable.

                          PART II. -- OTHER INFORMATION

ITEM 1. LEGAL PROCEEDINGS:  None.

ITEM 5. OTHER INFORMATION:  None.

ITEM 6. EXHIBITS AND REPORTS ON FORM 8-K:

(a)     Exhibits:

        Exhibit 27 Financial Data Schedule (electronic filing only).

(b)     Reports on Form 8-K:  None.


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<PAGE>   10

                                   SIGNATURES


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


                                        CMC SECURITIES CORPORATION I



Date:  May 6, 1999                      By: /s/ RONN K. LYTLE                  
                                            ------------------------------------
                                            Ronn K. Lytle
                                            Chairman and Chief Executive Officer




Date:  May 6, 1999                      By: /s/ ANDREW F. JACOBS               
                                            ------------------------------------
                                            Andrew F. Jacobs
                                            Executive Vice President - Finance
                                                Treasurer and Secretary



                                      -8-

<PAGE>   11
                               INDEX TO EXHIBITS

<TABLE>
<CAPTION>
Exhibit         
Number          Description
-------         -----------
<S>             <C>
 27             Financial Data Schedule
</TABLE>