<PAGE>   1
================================================================================


                UNITED STATES SECURITIES AND EXCHANGE COMMISSION
                             WASHINGTON, D.C. 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, 2000

                                       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: 333-64481

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

                    DELAWARE                                   75-2431915
        (State or other jurisdiction of                     (I.R.S. Employer
        incorporation or organization)                     Identification No.)

8401 NORTH CENTRAL EXPRESSWAY, SUITE 800, DALLAS, TX              75225
      (Address of principal executive offices)                  (Zip Code)

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

        Securities registered pursuant to Section 12(b) of the Act: None.

        Securities registered pursuant to Section 12(g) of the Act: None.

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
                                              -----     -----

INDICATE BY CHECK MARK IF DISCLOSURE OF DELINQUENT FILERS PURSUANT TO ITEM 405
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 [ ]

AT MARCH 15, 2001 THE AGGREGATE MARKET VALUE OF THE VOTING STOCK HELD BY
NONAFFILIATES WAS: NOT APPLICABLE.

THE REGISTRANT MEETS THE CONDITIONS SET FORTH IN GENERAL INSTRUCTION J(1)(a)
AND (b) OF FORM 10-K AND IS, THEREFORE, FILING THIS FORM WITH REDUCED DISCLOSURE
FORMAT.

NUMBER OF SHARES OF COMMON STOCK OUTSTANDING AT MARCH 15, 2001: 1,000

DOCUMENTS INCORPORATED BY REFERENCE: NONE.

================================================================================

<PAGE>   2


                          CMC SECURITIES CORPORATION IV

                          2000 FORM 10-K ANNUAL REPORT

                                TABLE OF CONTENTS

<TABLE>
<CAPTION>
                                                                           PAGE
                                                                           ----
<S>        <C>                                                             <C>
                                     PART I

ITEM  1.   BUSINESS.......................................................     1

ITEM  2.   PROPERTIES.....................................................     3

ITEM  3.   LEGAL PROCEEDINGS..............................................     3

                                     PART II

ITEM  5.   MARKET FOR THE REGISTRANT'S COMMON EQUITY
              AND RELATED STOCKHOLDER MATTERS.............................     3

ITEM  7.   MANAGEMENT'S DISCUSSION AND ANALYSIS OF
              FINANCIAL CONDITION AND RESULTS OF OPERATIONS...............     3

ITEM  7A.   QUANTITATIVE AND QUALITATIVE DISCLOSURES
              ABOUT MARKET RISK...........................................     3

ITEM  8.   FINANCIAL STATEMENTS AND SUPPLEMENTARY DATA....................     3

ITEM  9.   CHANGES IN AND DISAGREEMENTS WITH ACCOUNTANTS ON
              ACCOUNTING AND FINANCIAL DISCLOSURE.........................    13

                                     PART IV

ITEM 14.   EXHIBITS, FINANCIAL STATEMENT SCHEDULES AND
              REPORTS ON FORM 8-K.........................................    14
</TABLE>

<PAGE>   3


                                     PART I

ITEM 1. BUSINESS.

ORGANIZATION

CMC Securities Corporation IV (the "Company") was incorporated in Delaware on
May 6, 1992, as a special-purpose finance corporation and is a wholly-owned
subsidiary of Capstead Mortgage Corporation ("CMC"). CMC is a publicly-owned
real estate investment trust that, until late 1995, operated as a mortgage
conduit, purchasing and securitizing single-family residential mortgage loans.
The Company is managed by CMC (the "Manager").

Control of the Company within CMC's consolidated group changed twice during 1994
and 1995. In August 1994, CMC sold all the issued and outstanding shares of
capital stock in the Company to Capstead Inc., CMC's subsidiary formed primarily
to service single-family mortgage loans. On December 21, 1995, the Company was
merged with and into a newly formed and wholly-owned subsidiary of CMC (with a
corporate charter and organizational structure identical in almost all respects
to that of the Company) ("CMCSC IV-A") whereby the existence of the Company
ceased and CMCSC IV-A acquired all the assets and assumed all the liabilities of
the Company as the surviving entity. As a part of the merger, CMCSC IV-A changed
its name to CMC Securities Corporation IV, and from December 21, 1995 forward
has been referred to as the "Company."

The Company was formed primarily for the purpose of issuing collateralized
mortgage obligations ("Bonds" or "CMOs"), collateralized by mortgage-backed,
pass-through certificates ("Certificates") that evidence an interest in a pool
of mortgage loans secured by single-family residences. The Certificates pledged
as collateral for the Bonds will either be contributed by CMC or its affiliates
or purchased from third parties and will either be Ginnie Mae certificates,
Fannie Mac certificates, Freddie Mac certificates or mortgage pass-through
("Non-Agency") Certificates.

On August 17, 1992 the Securities and Exchange Commission declared effective an
amended registration statement filed by the Company covering the offering of a
maximum of $2 billion aggregate principal amount of CMOs. The Company commenced
operations with the September 30, 1994 issuance of its first series of CMOs. As
of December 31, 1999, the Company had issued 5 series of CMOs (none since 1997)
with an aggregate original principal balance of $2,003,125,000, $176,304,000 of
which were issued outside the registration statement as private placements. The
Company retained no beneficial interest in these CMOs, and as such, no economic
benefit will be received and no related net income or loss will be recognized
other than the amortization of unrecovered shelf issuance costs. These issuances
were accounted for as financings.

SPECIAL-PURPOSE FINANCE CORPORATION

Article III of the Company's Certificate of Incorporation limits the Company's
purposes to (i) issuing and selling CMOs, and receiving, owning, holding and
pledging as collateral the related Certificates, (ii) investing cash balances on
an interim basis in high quality short-term securities, and (iii) engaging in
other activities which are necessary or convenient to accomplish the foregoing
and are incidental thereto.


                                      -1-
<PAGE>   4

COMPETITION

The Company competes with other issuers of similar obligations, both with
respect to the acquisition of mortgage related collateral, securing the Bonds
and the placement of the CMOs. The Company also competes with entities that
issue and/or market numerous other competitive financial products.

EMPLOYEES

The Manager provides all executive and administrative personnel required by the
Company.

MANAGEMENT AGREEMENT

Pursuant to a management agreement, the Manager advises the Company with respect
to its investments and administers the day-to-day operations of the Company. The
management agreement is nonassignable except by consent of the Company and the
Manager. The management agreement may be terminated without cause at any time
upon 90 days written notice. In addition, the Company has the right to terminate
the management agreement upon the happening of certain specified events,
including a breach by the Manager of any provision contained in the management
agreement which remains uncured for 30 days after notice of such breach and the
bankruptcy or insolvency of the Manager.

The Manager is at all times subject to the supervision of the Company's Board of
Directors and has only such functions and authority as the Company delegates to
it. The Manager is responsible for the day-to-day operations of the Company and
performs such services and activities relating to the assets and operations of
the Company as may be appropriate. The Manager receives an annual basic
management fee of $10,000 per year for managing the assets pledged to secure
Bonds issued by the Company.

The Manager is required to pay employment expenses of its personnel (including
salaries, wages, payroll taxes, insurance, fidelity bonds, temporary help and
costs of employee benefit plans), and other office expenses, travel and other
expenses of directors, officers and employees of the Manager, accounting fees
and expenses incurred in supervising and monitoring the Company's investments or
relating to performance by the Manager of its functions. The Company is required
to pay all other expenses of operation (as defined in the management agreement).

SERVICING AND ADMINISTRATION

The originators of mortgage loans backing the Non-Agency Certificates may elect,
if they meet the Company's criteria for servicers, either to service the loans
they sell or to sell the loans with no agreement with respect to servicing. The
Company enters into servicing agreements with each servicer. As compensation for
services rendered under the servicing agreements, the servicers retain a
servicing fee, payable monthly, generally 1/4 of 1% per annum of the outstanding
principal balance of each mortgage loan serviced as of the last day of each
month. During 1998 Capstead Inc. serviced a significant number of the Company's
mortgage loans. This servicing was sold by Capstead Inc. in December 1998 to an
unaffiliated third party. No servicing fees were retained by Capstead Inc.
during 2000 and 1999; however, during 1998 Capstead Inc. retained fees from
mortgage loan payments for servicing mortgage loans of $940,000.


                                      -2-
<PAGE>   5

In addition, CMC acts as administrator with respect to certain of the Company's
Non-Agency Certificates and CMOs. During 2000, 1999 and 1998, CMC retained fees
for administering the Non-Agency Certificates and CMOs of $154,000, $180,000 and
$253,000, respectively.

ITEM 2. PROPERTIES.

The Company conducts operations at CMC's offices in Dallas, Texas.

ITEM 3. LEGAL PROCEEDINGS.

As of the date hereof, there are no material legal proceedings outside the
normal course of business to which the Company was a party or of which any of
its property was the subject.

                                     PART II

ITEM 5. MARKET FOR THE REGISTRANT'S COMMON EQUITY AND RELATED STOCKHOLDER
        MATTERS.

All of the Company's common stock is owned by CMC. Accordingly, there is no
public trading market for its common stock. To date the Company has not paid
dividends.

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

The Company commenced operations on September 30, 1994 with the issuance of its
first series of CMOs. Two additional series of CMOs were issued in both 1994 and
1997. The Company elected Real Estate Mortgage Investment Conduit ("REMIC")
status for tax purposes on these transactions. These issuances have been
accounted for as financings. As financings, CMO collateral and Bonds are
reflected on the balance sheet.

Since the Company did not retain any investment in the CMOs issued, no economic
benefit was or will be received and thus no net income or loss was or will be
recognized related to these CMOs other than amortization of unreimbursed shelf
issuance costs. The Company's net losses are due to this amortization and
operational costs incurred (management fees and professional fees).

LIQUIDITY AND CAPITAL RESOURCES

All ongoing cash CMO expenses 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 cash CMO
expenses. Cash flow requirements due to ongoing operational costs are funded by
CMC.

ITEM 7A. QUANTITATIVE AND QUALITATIVE DISCLOSURES ABOUT MARKET RISK

As discussed above, the Company will receive no economic benefit from the CMOs
it has issued. Accordingly the Company has no appreciable exposure to market
risks, including interest rate risk.

ITEM 8. FINANCIAL STATEMENTS AND SUPPLEMENTARY DATA.


                                      -3-
<PAGE>   6


                         REPORT OF INDEPENDENT AUDITORS


Stockholder and Board of Directors
CMC Securities Corporation IV

We have audited the accompanying balance sheets of CMC Securities Corporation IV
(a wholly-owned subsidiary of Capstead Mortgage Corporation) as of December 31,
2000 and 1999, and the related statements of operations, stockholder's equity,
and cash flows for each of the three years in the period ended December 31,
2000. These financial statements are the responsibility of the Company's
management. Our responsibility is to express an opinion on these financial
statements based on our audits.

We conducted our audits in accordance with auditing standards generally accepted
in the United States. Those standards require that we plan and perform the audit
to obtain reasonable assurance about whether the financial statements are free
of material misstatement. An audit includes examining, on a test basis, evidence
supporting the amounts and disclosures in the financial statements. An audit
also includes assessing the accounting principles used and significant estimates
made by management, as well as evaluating the overall financial statement
presentation. We believe that our audits provide a reasonable basis for our
opinion.

In our opinion, the financial statements referred to above present fairly, in
all material respects, the financial position of CMC Securities Corporation IV
at December 31, 2000 and 1999, and the results of its operations and its cash
flows for each of the three years in the period ended December 31, 2000, in
conformity with accounting principles generally accepted in the United States.



                                        ERNST & YOUNG LLP


Dallas, Texas
January 30, 2001


                                      -4-
<PAGE>   7


                          CMC SECURITIES CORPORATION IV
                                 BALANCE SHEETS
                      (IN THOUSANDS, EXCEPT PER SHARE DATA)


<TABLE>
<CAPTION>
                                                            DECEMBER 31
                                                    ---------------------------
                                                      2000              1999
                                                    ---------         ---------
<S>                                                 <C>               <C>
ASSETS
  Mortgage securities collateral                    $ 734,521         $ 828,194
  Cash and cash equivalents                                 5                 5
                                                    ---------         ---------
                                                    $ 734,526         $ 828,199
                                                    =========         =========

LIABILITIES
  Collateralized mortgage securities                $ 734,521         $ 828,115
  Accrued expenses                                         62                52
                                                    ---------         ---------
                                                      734,583           828,167
                                                    ---------         ---------

STOCKHOLDER'S EQUITY
  Common stock - $1.00 par value, 1 shares
    authorized, issued and outstanding                      1                 1
  Paid-in capital                                         489               465
  Undistributed loss                                     (547)             (434)
                                                    ---------         ---------
                                                          (57)               32
                                                    ---------         ---------
                                                    $ 734,526         $ 828,199
                                                    =========         =========
</TABLE>




See accompanying notes to financial statements.


                                      -5-
<PAGE>   8


                          CMC SECURITIES CORPORATION IV
                            STATEMENTS OF OPERATIONS
                                 (IN THOUSANDS)


<TABLE>
<CAPTION>
                                                  YEAR ENDED DECEMBER 31
                                            -----------------------------------
                                              2000         1999         1998
                                            ---------    ---------    ---------
<S>                                         <C>          <C>          <C>
Interest income on
  mortgage securities collateral            $  60,256    $  75,907    $ 115,627

Interest expense on collateralized
  mortgage securities                          60,335       75,967      115,697
                                            ---------    ---------    ---------
      Net interest expense                        (79)         (60)         (70)
                                            ---------    ---------    ---------

Other expenses:
  Management fees                                  10           10           10
  Professional fees                                24           10           17
                                            ---------    ---------    ---------
    Total other expenses                           34           20           27
                                            ---------    ---------    ---------
Net loss                                    $    (113)   $     (80)   $     (97)
                                            =========    =========    =========
</TABLE>




See accompanying notes to financial statements.



                                      -6-
<PAGE>   9


                          CMC SECURITIES CORPORATION IV
                       STATEMENTS OF STOCKHOLDER'S EQUITY
                       THREE YEARS ENDED DECEMBER 31, 2000
                                 (IN THOUSANDS)


<TABLE>
<CAPTION>
                              COMMON STOCK        PAID-IN   UNDISTRIBUTED
                           SHARES      AMOUNT     CAPITAL   INCOME (LOSS)    TOTAL
                           ------      ------     -------   -------------    -----
<S>                        <C>         <C>        <C>       <C>              <C>
Balance at
  January 1, 1998              1       $   1       $ 490        $(257)       $ 234

Capital distribution          --          --         (58)          --          (58)

Net loss                      --          --          --          (97)         (97)
                           -----       -----       -----        -----        -----

Balance at
  December 31, 1998            1           1         432         (354)          79

Capital contribution          --          --          33           --           33

Net loss                      --          --          --          (80)         (80)
                           -----       -----       -----        -----        -----

Balance at
  December 31, 1999            1           1         465         (434)          32

Capital contribution          --          --          24           --           24

Net loss                      --          --          --         (113)        (113)
                           -----       -----       -----        -----        -----

Balance at
  December 31, 2000            1       $   1       $ 489        $(547)       $ (57)
                           =====       =====       =====        =====        =====
</TABLE>




See accompanying notes to financial statements.


                                      -7-
<PAGE>   10


                          CMC SECURITIES CORPORATION IV
                            STATEMENTS OF CASH FLOWS
                                 (IN THOUSANDS)


<TABLE>
<CAPTION>
                                                     YEAR ENDED DECEMBER 31
                                             ---------------------------------------
                                               2000           1999           1998
                                             ---------      ---------      ---------
<S>                                          <C>            <C>            <C>
OPERATING ACTIVITIES:
  Net loss                                   $    (113)     $     (80)     $     (97)
  Noncash item - amortization
    of discount and premium                         70             33             19
  Net change in other assets and
    accrued expenses                                10             10             10
                                             ---------      ---------      ---------
        Net cash used in
         operating activities                      (33)           (37)           (68)
                                             ---------      ---------      ---------

INVESTING ACTIVITIES:
  Mortgage securities collateral:
    Principal collections on collateral         96,005        357,983        559,522
    Decrease in accrued interest
      receivable                                   595          2,099          3,745
                                             ---------      ---------      ---------
        Net cash provided by
         investing activities                   96,600        360,082        563,267
                                             ---------      ---------      ---------

FINANCING ACTIVITIES:
  Collateralized mortgage securities:
    Principal payments on securities           (96,005)      (357,983)      (559,522)
    Decrease in accrued interest payable          (586)        (2,091)        (3,620)
  Capital contribution (distribution)               24             33            (58)
                                             ---------      ---------      ---------
        Net cash used in
         financing activities                  (96,567)      (360,041)      (563,200)
                                             ---------      ---------      ---------

Net change in cash and cash equivalents             --              4             (1)

Cash and cash equivalents at
  beginning of year                                  5              1              2
                                             ---------      ---------      ---------

Cash and cash equivalents at end
    of year                                  $       5      $       5      $       1
                                             =========      =========      =========
</TABLE>




See accompanying notes to financial statements.


                                      -8-
<PAGE>   11


                          CMC SECURITIES CORPORATION IV
                          NOTES TO FINANCIAL STATEMENTS
                                DECEMBER 31, 1999


NOTE A -- BUSINESS

CMC Securities Corporation IV (the "Company") was incorporated in Delaware on
May 6, 1992, as a special-purpose finance corporation primarily to issue bonds
collateralized by whole loans or mortgage-backed securities. Capstead Inc.
acquired the Company from Capstead Mortgage Corporation ("CMC"), the then parent
of Capstead Inc., on August 10, 1994 pursuant to a Stock Purchase Agreement
prior to commencement of operations; however, control of the Company was
transferred back to CMC on December 21, 1995 pursuant to an Agreement and Plan
of Merger.

NOTE B -- ACCOUNTING POLICIES

USE OF ESTIMATES

The preparation of the financial statements in conformity with generally
accepted accounting principles requires management to make estimates and
assumptions that affect the amounts reported in the financial statements and
accompanying notes. Actual results could differ from those estimates.

SECURITIES HELD-TO-MATURITY

Management determines the appropriate classification of debt securities at the
time of purchase and reevaluates such designation as of each balance sheet date.
Debt securities are classified as held-to-maturity when the Company has the
positive intent and ability to hold the securities to maturity. Held-to-maturity
securities are stated at amortized cost.

MORTGAGE SECURITIES COLLATERAL

Mortgage securities collateral consists of debt securities classified as
held-to-maturity. Amortized cost is adjusted for amortization of premiums and
discounts over the estimated life of the security using the interest method.
Such amortization is included in related interest income.

Mortgage securities collateral is subject to changes in value because of changes
in interest rates and rates of prepayment, as well as failure of the mortgagor
to perform under the mortgage agreement. The Company has limited its exposure to
these risks by issuing collateralized mortgage securities, using a
senior/subordinate structure (see Note F).

ALLOWANCE FOR POSSIBLE LOSSES

The Company provides for possible losses on its investments in amounts which it
believes are adequate relative to the risk inherent in such investments.

COLLATERALIZED MORTGAGE SECURITIES

Collateralized mortgage securities are carried at their unpaid principal
balances, net of unamortized discount or premium. Any discount or premium is


                                      -9-
<PAGE>   12


recognized as an adjustment to interest expense by the interest method over the
life of the related securities.

INCOME TAXES

Since its inception through August 9, 1994, the Company operated as a qualified
real estate investment trust ("REIT") subsidiary of CMC, which itself is a REIT,
and was combined with CMC for federal income tax purposes. REITs are not taxed
at the corporate level provided that certain requirements are met. From August
10, 1994 through December 21, 1995 the Company was consolidated for income tax
purposes with Capstead Inc., which is not a REIT; however, due to losses
incurred during this period, no provision was made for federal income taxes.
Beginning December 21, 1995 the Company once again began operating as a
qualified REIT subsidiary of CMC. Accordingly, no provision is required for
federal income taxes.

CASH AND CASH EQUIVALENTS

Cash and cash equivalents include cash on hand and highly liquid investments
with original maturities of three months or less.

NOTE C -- MORTGAGE SECURITIES COLLATERAL

Mortgage securities collateral consists of conventional single-family mortgage
loans which are pledged to secure repayment of the collateralized mortgage
securities. All principal and interest payments on the collateral are remitted
directly to a collection account maintained by a trustee. The trustee is
responsible for reinvesting those funds in short-term investments. All
collections on the collateral and the reinvestment income earned thereon are
available for payment of principal and interest on the collateralized mortgage
securities. The components of mortgage securities collateral are summarized as
follows (in thousands):

<TABLE>
<CAPTION>
                                                     DECEMBER 31
                                              -------------------------
                                                2000            1999
                                              ---------       ---------
<S>                                           <C>             <C>
        Mortgage collateral                   $ 736,082       $ 832,087
        Short-term investments                        9               9
        Accrued interest receivable               4,506           5,101
                                              ---------       ---------
         Total collateral                       740,597         837,197
        Unamortized discount                     (6,076)         (9,003)
                                              ---------       ---------

        Net collateral                        $ 734,521       $ 828,194
                                              =========       =========
</TABLE>

The weighted average effective interest rate for mortgage securities collateral
was 7.76% and 8.06% during 2000 and 1999, respectively.

NOTE D -- COLLATERALIZED MORTGAGE SECURITIES

Each series of collateralized mortgage securities consists of various classes,
some of which may be deferred interest, interest-only and principal-only
securities. Interest is payable monthly at specified rates for all classes other
than deferred interest securities. Generally, principal payments on each series
are made to each class in the order of their stated maturities so that no
payment of principal will be made on any class until all classes having an
earlier stated maturity have been paid in full. Generally, payments of principal
and interest on deferred interest securities


                                      -10-
<PAGE>   13

will commence only upon payment in full of some or all other classes. Prior to
that time, interest accrues on the deferred interest securities and the amount
accrued is added to the unpaid principal balance. Interest payments on
interest-only bonds are based on a specified notional amount used only for the
calculation of interest and no payments of principal are made. Principal-only
bonds remit principal payments and no interest is paid.

The components of collateralized mortgage securities are summarized as follows
(dollars in thousands):

<TABLE>
<CAPTION>
                                                         DECEMBER 31
                                                 ----------------------------
                                                   2000                1999
                                                 --------            --------
<S>                                              <C>                 <C>
  Collateralized mortgage securities             $736,082            $832,087
  Accrued interest payable                          4,449               5,035
                                                 --------            --------
    Total obligation                              740,531             837,122
  Unamortized discount                             (6,010)             (9,007)
                                                 --------            --------

  Net obligation                                 $734,521            $828,115
                                                 ========            ========

Range of average interest rate                6.36% to 8.74%     6.35% to 8.55%
Stated maturities                              2024 to 2027       2024 to 2027
Number of series                                     5                  5
</TABLE>

The maturity of each series of securities is directly affected by the rate of
principal prepayments on the related mortgage securities collateral. Each series
of securities is also subject to redemption at the Company's option provided
that certain requirements specified in the related indenture have been met
(referred to as "clean-up calls"). As a result, the actual maturity of any
series of securities is likely to occur earlier than its stated maturity.

The weighted average effective interest rate for collateralized mortgage
securities was 7.77% and 8.06% during 2000 and 1999, respectively. Interest
payments on collateralized mortgage securities of $57,280,000, $70,489,000 and
$110,882,000 were made during 2000, 1999 and 1998, respectively.

NOTE E -- DISCLOSURES REGARDING FAIR VALUES OF FINANCIAL INSTRUMENTS

The estimated fair value of financial instruments have been determined by the
Company 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 the Company could realize 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 carrying amount of cash and cash equivalents approximates fair value. The
fair value of mortgage securities collateral was estimated using either quoted
market prices, when available, including quotes made by CMC's lenders in
connection with designating collateral for repurchase arrangements. The fair
value of collateralized mortgage securities is dependent upon the
characteristics of the mortgage securities collateral pledged to secure the
issuance. Therefore, fair value was based on the same method used for
determining fair value for the underlying mortgage securities collateral,


                                      -11-
<PAGE>   14

adjusted for credit enhancements. The following table summarizes the fair value
of financial instruments (in thousands):

<TABLE>
<CAPTION>
                                        DECEMBER 31, 2000           DECEMBER 31, 1999
                                      ----------------------      ----------------------
                                      CARRYING       FAIR         CARRYING       FAIR
                                       AMOUNT        VALUE         AMOUNT        VALUE
                                      --------      --------      --------      --------
<S>                                   <C>           <C>           <C>           <C>
ASSETS
  Cash and cash equivalents           $      5      $      5      $      5      $      5
  Mortgage securities collateral       734,521       735,955       828,194       834,267

LIABILITIES
  Collateralized mortgage
    securities                         734,521       735,061       828,115       843,839
</TABLE>

The table above reflects the estimated fair value of mortgage securities
collateral and cash equivalents, which reflect gross unrealized gains of $7.3
million and gross unrealized losses of $5.8 million as of December 31, 2000, and
gross unrealized gains of $6.4 million and gross unrealized losses of $318,000
as of December 31, 1999.

NOTE F -- ALLOWANCE FOR POSSIBLE LOSSES

The Company has limited exposure to losses on mortgage securities collateral
because the Company's collateralized mortgage securities are issued in a
senior/subordinate structure where the investor in the subordinate classes
assumes the risks of losses due to typical mortgagor default and special
hazards. Special hazards are typically catastrophic events that are unable to be
predicted (e.g., earthquakes). Because of its limited exposure to losses, the
Company has determined that an allowance for possible losses is not warranted at
December 31, 2000.

Since 23% and 18% of mortgage securities collateral is secured by properties
located in California and Virginia, respectively, the Company has a
concentration of risk related to these markets. However, the Company's exposure
arising from this concentration is reduced by the use of the senior/subordinate
structure for securitizations.

NOTE G -- MANAGEMENT AGREEMENT

The Company operates under a $10,000 per year management agreement with CMC (the
"Manager"). The agreement provides that the Manager will advise the Company with
respect to all facets of its business and administer the day-to-day operations
of the Company under the supervision of the Company's Board of Directors. The
Manager pays among other things, salaries and benefits of its personnel,
accounting fees and expenses, and other office expenses incurred in supervising
and monitoring the Company's investments.

NOTE H -- TRANSACTIONS WITH RELATED PARTIES

The Company has entered into servicing agreements with Capstead Inc., the
provisions of which are typical of such agreements in the mortgage servicing
industry. Capstead Inc. sold this servicing to an unaffiliated third party in
December 1998. Under the servicing agreements, Capstead Inc. retained from
interest collected a servicing fee generally 1/4 of 1% per annum of the
outstanding principal balance of mortgage loans serviced. No servicing fees


                                      -12-
<PAGE>   15

were retained by Capstead Inc. during 2000 and 1999; however, servicing fees of
$940,000 were retained by Capstead Inc. in 1998.

CMC acts as administrator in relation to certain of the Company's Non-Agency
Certificates and CMOs in which it performs certain administrative functions. CMC
receives fees of approximately 0.015% to 0.04% per annum of the outstanding
principal amount of the bonds, after deducting trustee fees. Such fees totaled
$154,000, $180,000 and $253,000 in 2000, 1999 and 1998, respectively.

The Company has a $1 million revolving subordinated promissory note with CMC
under which interest accrues on amounts payable based on the annual federal
short-term rate as published by the Internal Revenue Service. This note expires
January 1, 2002. Repayments may be made as funds are available.

NOTE I -- NET INTEREST INCOME ANALYSIS (UNAUDITED)

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

<TABLE>
<CAPTION>
                                      2000                    1999                 1998
                               ------------------      ------------------   ------------------
                                          AVERAGE                 AVERAGE              AVERAGE
                               AMOUNT      RATE        AMOUNT      RATE      AMOUNT     RATE
                               -------    -------      -------    -------   --------   -------
<S>                            <C>        <C>          <C>        <C>       <C>        <C>
Interest income on
  mortgage securities
  collateral                   $60,256     7.76%       $75,907     8.06%    $115,627    7.92%
Interest expense on
  collateralized
  mortgage securities           60,335     7.77         75,967     8.06      115,697    7.93
                               -------                 -------              --------
Net interest expense           $   (79)                $   (60)             $    (70)
                               =======                 =======              ========
</TABLE>

The following 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>
                                                                2000/1999
                                                   ------------------------------------
                                                    RATE          VOLUME        TOTAL
                                                   -------       --------      --------
<S>                                                <C>           <C>           <C>
Interest income on mortgage
  securities collateral                            $(2,722)      $(12,929)     $(15,651)
Interest expense on collateralized
  mortgage securities                               (2,695)       (12,937)      (15,632)
                                                   -------       --------      --------
                                                   $   (27)      $      8      $    (19)
                                                   =======       ========      ========
</TABLE>


<TABLE>
<CAPTION>
                                                                 1999/1998
                                                    -----------------------------------
                                                     RATE         VOLUME        TOTAL
                                                    ------       --------      --------
<S>                                                 <C>          <C>           <C>
Interest income on mortgage
  securities collateral                             $1,953       $(41,673)     $(39,720)
Interest expense on collateralized
  mortgage securities                                1,981        (41,711)      (39,730)
                                                    ------       --------      --------
                                                    $  (28)      $     38      $     10
                                                    ======       ========      ========
</TABLE>

ITEM 9. CHANGES IN AND DISAGREEMENTS WITH ACCOUNTANTS ON ACCOUNTING AND
        FINANCIAL DISCLOSURE.

None.


                                      -13-
<PAGE>   16



                                     PART IV

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

(a)    Documents filed as part of this report:

       1.  The following financial statements of the Company are included in
           ITEM 8:

<TABLE>
<CAPTION>
                                                                                PAGE
                                                                                ----
<S>                                                                             <C>
           Balance Sheets - December 31, 2000 and 1999                           5
           Statements of Operations - Three Years Ended December 31, 2000        6
           Statements of Stockholder's Equity -
             Three Years Ended December 31, 2000                                 7
           Statements of Cash Flows - Three Years Ended December 31, 2000        8
           Notes to Financial Statements - December 31, 2000                     9
</TABLE>

       2.  Financial Statement Schedules: None.

           All schedules for which provision is made in the applicable
           accounting regulation of the Securities and Exchange Commission are
           not required under the related instructions or are inapplicable and,
           therefore, have been omitted.

       3.  Exhibits:

<TABLE>
<CAPTION>
           EXHIBIT
           NUMBER
           -------
<S>                  <C>
             2.1     Stock Purchase Agreement dated as of August 10, 1994(4)
             3.1     Certificate of Incorporation(1)
             3.2     Amendment to Certificate of Incorporation(4)
             3.3     Bylaws(1)
             3.4     Certificate of Merger of the Company into CMCSC IV-A, filed
                     and Certified on December 21, 1995 with the Secretary of
                     State of Delaware(10)
             3.5     Bylaws of CMCSC IV-A(10)
             3.6     Certificate of Incorporation of CMCSC IV-A, as filed with
                     the Secretary of State of Delaware on December 13, 1995(10)
             4.1     Form of Indenture between Registrant and Texas Commerce
                     Bank, National Association, as Trustee(1)
             4.2     Form of First Supplement to the Indenture(5)
             4.3     Form of Second Supplement to the Indenture(6)
             4.4     Form of Third Supplement to the Indenture(7)
             4.5     Form of Fourth Supplement to the Indenture(8)
             4.6     Form of Fifth Supplement to the Indenture(9)
            10.1     Form of Pooling and Administrative Agreement(1)
            10.4     Management Agreement between Registrant and Capstead
                     Advisers, Inc. dated January 1, 1993(2)
            10.5     Amended Management Agreement between Registrant and
                     Capstead Advisers, Inc. dated October 1, 1993(3)
            23       Consent of Ernst & Young LLP, Independent Auditors*
</TABLE>



                                      -14-
<PAGE>   17


                                     PART IV

                              ITEM 14. - CONTINUED


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

-----------------
(1)    Previously filed with the Commission as an exhibit to the Company's
       Registration Statement on Form S-3 (No. 33-47912) filed May 14, 1992
(2)    Previously filed with the Commission as an exhibit to the Registrant's
       Annual Report on Form 10-K for the year ended December 31, 1992
(3)    Previously filed with the Commission as an exhibit to the Registrant's
       Annual Report on Form 10-K for the year ended December 31, 1993
(4)    Previously filed with the Commission as an Exhibit to the Registrant's
       Quarterly Report on Form 10-Q for the quarter ended June 30, 1994
(5)    Previously filed with the Commission as an exhibit to the Registrant's
       Current Report on Form 8-K on September 30, 1994
(6)    Previously filed with the Commission as an exhibit to the Registrant's
       Current Report on Form 8-K on October 31, 1994
(7)    Previously filed with the Commission as an exhibit to the Registrant's
       Current Report on Form 8-K on December 30, 1994
(8)    Previously filed with the Commission as an exhibit to the Registrant's
       Current Report on Form 8-K on September 30, 1997
(9)    Previously filed with the Commission as an exhibit to the Registrant's
       Current Report on Form 8-K on October 29, 1997
(10)   Previously filed with the Commission as an exhibit to the Registrant's
       Current Report on Form 10-K for the year ended December 31, 1995
*      Filed herewith.



                                      -15-
<PAGE>   18


                                   SIGNATURES


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


                                        CMC SECURITIES CORPORATION IV
                                                   REGISTRANT


Date: March 15, 2001                    By: /s/ ANDREW F. JACOBS
                                            --------------------------------
                                                Andrew F. Jacobs
                                            Executive Vice President-Finance


Pursuant to the requirements of the Securities Exchange Act of 1934, this report
has been signed below by the following persons on behalf of the Registrant and
in the capacities indicated below and on the dates indicated.


<TABLE>
<S>                                <C>                            <C>
/s/ ANDREW F. JACOBS               Executive Vice President -     March 15, 2001
------------------------------       Finance
       (Andrew F. Jacobs)


/s/ PHILLIP A. REINSCH             Senior Vice President -        March 15, 2001
------------------------------       Control
       (Phillip. A. Reinsch)


/s/ MAURICE MCGRATH                Director                       March 15, 2001
------------------------------
        (Maurice McGrath)
</TABLE>



SUPPLEMENTAL INFORMATION TO BE FURNISHED WITH REPORTS FILED PURSUANT TO SECTION
15(d) OF THE ACT BY REGISTRANTS WHICH HAVE NOT REGISTERED SECURITIES PURSUANT TO
SECTION 12 OF THE ACT.

No annual report or proxy material has been sent to security holders.



                                      -16-
<PAGE>   19


                                INDEX TO EXHIBITS


<TABLE>
<CAPTION>
        EXHIBIT
        NUMBER                     DESCRIPTION
        -------                    -----------
<S>              <C>
         2.1     Stock Purchase Agreement dated as of August 10, 1994(4)
         3.1     Certificate of Incorporation(1)
         3.2     Amendment to Certificate of Incorporation(4)
         3.3     Bylaws(1)
         3.4     Certificate of Merger of the Company into CMCSC IV-A, filed and
                 Certified on December 21, 1995 with the Secretary of State of
                 Delaware(10)
         3.5     Bylaws of CMCSC IV-A(10)
         3.6     Certificate of Incorporation of CMCSC IV-A, as filed with the
                 Secretary of State of Delaware on December 13, 1995(10)
         4.1     Form of Indenture between Registrant and Texas Commerce Bank,
                 National Association, as Trustee(1)
         4.2     Form of First Supplement to the Indenture(5)
         4.3     Form of Second Supplement to the Indenture(6)
         4.4     Form of Third Supplement to the Indenture(7)
         4.5     Form of Fourth Supplement to the Indenture(8)
         4.6     Form of Fifth Supplement to the Indenture(9)
        10.1     Form of Pooling and Administrative Agreement(1)
        10.4     Management Agreement between Registrant and Capstead Advisers,
                 Inc. dated January 1, 1993(2)
        10.5     Amended Management Agreement between Registrant and Capstead
                 Advisers, Inc. dated October 1, 1993(3)
        23       Consent of Ernst & Young LLP, Independent Auditors*
</TABLE>

-----------------
(1)    Previously filed with the Commission as an exhibit to the Company's
       Registration Statement on Form S-3 (No. 33-47912) filed May 14, 1992
(2)    Previously filed with the Commission as an exhibit to the Registrant's
       Annual Report on Form 10-K for the year ended December 31, 1992
(3)    Previously filed with the Commission as an exhibit to the Registrant's
       Annual Report on Form 10-K for the year ended December 31, 1993
(4)    Previously filed with the Commission as an Exhibit to the Registrant's
       Quarterly Report on Form 10-Q for the quarter ended June 30, 1994
(5)    Previously filed with the Commission as an exhibit to the Registrant's
       Current Report on Form 8-K on September 30, 1994
(6)    Previously filed with the Commission as an exhibit to the Registrant's
       Current Report on Form 8-K on October 31, 1994
(7)    Previously filed with the Commission as an exhibit to the Registrant's
       Current Report on Form 8-K on December 30, 1994
(8)    Previously filed with the Commission as an exhibit to the Registrant's
       Current Report on Form 8-K on September 30, 1997
(9)    Previously filed with the Commission as an exhibit to the Registrant's
       Current Report on Form 8-K on October 29, 1997
(10)   Previously filed with the Commission as an exhibit to the Registrant's
       Current Report on Form 10-K for the year ended December 31, 1995
*      Filed herewith.