<Page>

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

                                    FORM 10-Q

(Mark One)

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

For the quarterly period ended MARCH 31, 2005

                   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  0-25000

                          ML PRINCIPAL PROTECTION L.P.
                          ----------------------------
                          (Exact Name of Registrant as
                            specified in its charter)

            Delaware                         13-3750642 (Registrant)
- ---------------------------------            -----------------------
(State or other jurisdiction of              (IRS Employer Identification No.)
incorporation or organization)

                    c/o Merrill Lynch Investment Managers LLC
                                  222 Broadway
                                   27th Floor
                             New York, NY 10038-2510
                             -----------------------
                    (Address of principal executive offices)
                                   (Zip Code)

                                  609-282-6996
                 ---------------------------------------------
              (Registrant's telephone number, including area code)

         Indicate by check mark whether the registrant (1) has filed all reports
required to be filed by Section 13 or 15 (d) of the Securities Exchange Act of
1934 during the preceding 12 months (or for such shorter period that the
registrant was required to file such reports), and (2) has been subject to such
filing requirements for the past 90 days. Yes /X/ No / /

<Page>

                         PART I - FINANCIAL INFORMATION

Item 1.  Financial Statements

                          ML PRINCIPAL PROTECTION L.P.
                        (A DELAWARE LIMITED PARTNERSHIP)

                        STATEMENTS OF FINANCIAL CONDITION

<Table>
<Caption>
                                                                  MARCH 31,
                                                                    2005          DECEMBER 31,
                                                                (UNAUDITED)          2004
                                                               --------------   --------------
                                                                          
ASSETS

Equity in commodity futures trading accounts:
  Cash                                                         $      512,483   $      509,498
Investment in Global Horizons                                      12,083,012                -
Receivable from MM LLC                                                      -       13,053,547
Accrued interest receivable                                             1,121              964
                                                               --------------   --------------

         TOTAL                                                 $   12,596,616   $   13,564,009
                                                               ==============   ==============
LIABILITIES AND PARTNERS' CAPITAL
LIABILITIES:
Redemptions payable                                            $      142,391   $       79,561
Payable to Global Horizons                                            371,213          430,901
                                                               --------------   --------------

       Total liabilities                                              513,604          510,462
                                                               --------------   --------------
PARTNERS' CAPITAL:
 General Partners (160,738 and 11,905,083 Units)                      157,334          160,719
 Limited Partners (12,183,681 and 11,758,530 Units)                11,925,678       12,892,828
                                                               --------------   --------------

       Total partners' capital                                     12,083,012       13,053,547
                                                               --------------   --------------

         TOTAL                                                 $   12,596,616   $   13,564,009
                                                               ==============   ==============
NET ASSET VALUE PER UNIT (NOTE 3)
</Table>

See notes to financial statements.

                                        2
<Page>

                          ML PRINCIPAL PROTECTION L.P.
                        (A DELAWARE LIMITED PARTNERSHIP)

                            STATEMENTS OF OPERATIONS
                                   (unaudited)

<Table>
<Caption>
                                                               FOR THE THREE    FOR THE THREE
                                                                MONTHS ENDED     MONTHS ENDED
                                                                 MARCH 31,        MARCH 31,
                                                                    2005             2004
                                                               --------------   --------------
                                                                          
TRADING REVENUE (LOSS):
  Trading profit (loss):
  Realized                                                     $      (77,128)  $    1,351,816
  Change in unrealized                                                (21,680)        (280,280)
                                                               --------------   --------------

       Total trading revenue (loss)                                   (98,808)       1,071,536
                                                               --------------   --------------
INVESTMENT INCOME

  Interest                                                             72,324           35,993
                                                               --------------   --------------
EXPENSES:
  Profit Shares                                                        33,958          175,014
  Brokerage commissions                                               211,003          271,299
  Administrative fees                                                   7,276            9,338
                                                               --------------   --------------

       Total expenses                                                 252,237          455,651
                                                               --------------   --------------

NET INVESTMENT LOSS                                                  (179,913)        (419,658)
                                                               --------------   --------------

NET INCOME (LOSS)                                              $     (278,721)  $      651,878
                                                               ==============   ==============
NET INCOME (LOSS) PER UNIT:
  Weighted average number of General Partner
  and Limited Partner Units outstanding                            12,629,531       13,873,073
                                                               ==============   ==============
  Net income (loss) per weighted average
  General Partner and Limited Partner Unit                     $      (0.0221)  $       0.0470
                                                               ==============   ==============
</Table>

Substantially all items of income and expense are derived from the investment in
Global Horizons or MM LLC. (Note 2)

See notes to financial statements.

                                        3
<Page>

                          ML PRINCIPAL PROTECTION L.P.
                        (A DELAWARE LIMITED PARTNERSHIP)

                   STATEMENTS OF CHANGES IN PARTNERS' CAPITAL
               FOR THE THREE MONTHS ENDED MARCH 31, 2005 AND 2004
                                   (unaudited)

<Table>
<Caption>
                                                           GENERAL           LIMITED
                                           UNITS           PARTNER           PARTNERS           TOTAL
                                      --------------    --------------    --------------    --------------
                                                                                
PARTNERS' CAPITAL,
 DECEMBER 31, 2003                        11,909,517    $      159,703    $   15,281,993    $   15,441,696

Conversion of Units (Note 3)               2,266,687                 -               314               314

Net income                                         -             6,807           645,071           651,878

Redemptions                               (1,161,812)                -        (1,307,162)       (1,307,162)
                                      --------------    --------------    --------------    --------------
PARTNERS' CAPITAL,
 MARCH 31, 2004                           13,014,392    $      166,510    $   14,620,216    $   14,786,726
                                      ==============    ==============    ==============    ==============
PARTNERS' CAPITAL,
 DECEMBER 31, 2004                        11,905,083    $      160,719    $   12,892,828        13,053,547

Conversion of Units (Note 3)               1,149,203                19               714               733

Net loss                                           -            (3,404)         (275,317)         (278,721)

Redemptions                                 (709,861)                -          (692,547)         (692,547)
                                      --------------    --------------    --------------    --------------
PARTNERS' CAPITAL,
 MARCH 31, 2005                           12,344,425    $      157,334    $   11,925,678    $   12,083,012
                                      ==============    ==============    ==============    ==============
</Table>

See notes to financial statements.

                                        4
<Page>

                          ML PRINCIPAL PROTECTION L.P.
                        (A DELAWARE LIMITED PARTNERSHIP)

                          NOTES TO FINANCIAL STATEMENTS
                                   (unaudited)

1.   SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES

     In the opinion of management, the financial statements contain all
     adjustments necessary to present fairly the financial position of ML
     Principal Protection L.P. (the "Partnership") as of March 31, 2005, and the
     results of its operations for the three months ended March 31, 2005 and
     2004. The operating results for the interim periods may not be indicative
     of the results for the full year.

     Certain information and footnote disclosures normally included in quarterly
     financial statements prepared in accordance with accounting principles
     generally accepted in the United States of America have been omitted. It is
     suggested that these financial statements be read in conjunction with the
     financial statements and notes thereto included in the Partnership's Annual
     Report on Form 10-K filed with the Securities and Exchange Commission for
     the year ended December 31, 2004.

2.   INVESTMENTS

     Effective December 31, 2004, the Partnership redeemed its entire interest
     in ML Multi-Manager LLC ("MM LLC") and proceeds were invested on
     January 2, 2005 in Global Horizons I L.P. ("Global Horizons"), formerly
     known as ML Global Horizons L.P.

     As of March 31, 2005 the Partnership had an investment in Global Horizons
     of $12,083,012 and the Partnership's percentage ownership share of Global
     Horizons was 4.61%.

                                        5
<Page>

Condensed statement of financial condition and statements of operations for
Global Horizons and MM LLC are set forth as follows:

<Table>
<Caption>
                                 GLOBAL HORIZONS                 MM LLC
                            -------------------------   -------------------------
                                    MARCH 31,                 DECEMBER 31,
                                      2005                        2004
                                   (UNAUDITED)
                            -------------------------   -------------------------
                                                  
     Assets                 $             276,827,516   $             101,421,710
                            =========================   =========================
     Liabilities            $              14,967,416   $             101,421,710
     Partners' Capital                    261,860,100                           -
                            -------------------------   -------------------------
     Total                  $             276,827,516   $             101,421,710
                            =========================   =========================

<Caption>
                                 GLOBAL HORIZONS                 MM LLC
                            -------------------------   -------------------------
                              FOR THE THREE MONTHS        FOR THE THREE MONTHS
                              ENDED MARCH 31, 2005        ENDED MARCH 31, 2004
                                   (UNAUDITED)                 (UNAUDITED)
                            -------------------------   -------------------------
                                                  
     Trading Revenues
     and
     Interest Income        $                 163,766   $                5,608,071

     Expenses                               4,834,520                    2,477,284
                            -------------------------   -------------------------

     Net income (loss)      $              (4,670,754)  $                3,130,787
                            =========================   ==========================
</Table>

3.   NET ASSET VALUE PER UNIT

     Prior to the opening of business on January 2, 2005, Series A 2003, Series
     2004 and Series S were consolidated into a new series, Series 2005, with a
     $1.00 Unit Net Asset Value. The aggregate Net Asset Value of each
     investor's new Units is equal to the aggregate Net Asset Value of their
     original Units at December 31, 2004. The consolidation had no adverse
     economic effect on the investors. MLIM LLC contributed $733 to the
     Partnership, the amount necessary due to the effects of rounding, to ensure
     that all investors received Units equal in value to their original holdings
     at December 31, 2004. The following is a listing of the number of new Units
     each investor received of Series 2005 for each Unit of their original
     series holding:

<Table>
<Caption>
                           NUMBER
       SERIES             OF UNITS
       ------             --------
                      
     A 2003                1.108721
     2004                  1.005565
     S                   125.174168
</Table>

     Prior to the opening of business on January 2, 2004, Series G, H, and O
     through R, those series that had come to term on or before December 31,
     2003, but after December 31, 2002, were consolidated into a new series,
     Series 2004, with a $1.00 per Unit Net Asset Value. The aggregate Net Asset
     Value of each investor's new Units is equal to the aggregate Net Asset
     Value of their original Units at December 31, 2003. The consolidation had
     no adverse economic effect on the investors. The General Partner
     contributed $314 to the Partnership, the amount necessary due to the
     effects of rounding to ensure all investors received Units equal in value
     to their original holdings at December

                                        6
<Page>

     31, 2003. The following is a list of the number of new Units each investor
     received of Series 2004 for each Unit of their original series holding.

<Table>
<Caption>
                           NUMBER
       SERIES             OF UNITS
       ------             --------
                      
     G                   110.859969
     H                   102.336331
     O                   129.904347
     P                   132.546751
     Q                   122.531124
     R                   123.779041
</Table>

     After the series consolidations, the brokerage commission rates for Series
     2005 and Series 2004 were reduced to a monthly rate of 0.604 of 1% (a 7.25%
     annual rate).

     At March 31, 2005 and December 31, 2004, the Net Asset Values of the
     different series of Units were:

     March 31, 2005
     (unaudited)

<Table>
<Caption>
                                                                   Net Asset Value
            Series       Net Asset Value       Number of Units        per Unit
            ------       ---------------       ---------------     ---------------
                                                               
             2005        $    12,083,012            12,344,419          $   0.9788
                         ===============       ===============
</Table>

     December 31, 2004

<Table>
<Caption>
                                                                   NET ASSET VALUE
            SERIES       NET ASSET VALUE       NUMBER OF UNITS         PER UNIT
            ------       ---------------       ---------------     ---------------
                                                          
     A 2003 Units        $    11,000,919             9,922,463     $        1.1087
     2004 Units                1,993,167             1,982,139              1.0056
     S Units                      59,461                   475              125.17
                         ---------------       ---------------
                         $    13,053,547            11,905,077
                         ===============       ===============
</Table>

4.   FAIR VALUE AND OFF-BALANCE SHEET RISK

     The Partnership invests indirectly in derivative instruments as a result of
     its investment in Global Horizons, but does not itself hold any derivative
     instrument positions. The nature of this Partnership has certain risks,
     which cannot be presented on the financial statements. The following
     summarizes, resulting from its investment in Global Horizons, some of those
     risks.

     MARKET RISK

     Derivative instruments involve varying degrees of off-balance sheet market
     risk. Changes in the level or volatility of interest rates, foreign
     currency exchange rates or the market values of the financial instruments
     or commodities underlying such derivative instruments frequently result in
     changes in the Partnership's allocation of net unrealized profit on such
     derivative instruments as reflected in the Statements of Financial
     Condition of Global Horizons. The Partnership's exposure to

                                        7
<Page>

     market risk is influenced by a number of factors, including the
     relationships among the derivative instruments held by Global Horizons as
     well as the volatility and liquidity of the markets in which such
     derivative instruments are traded.

     Merrill Lynch Investment Managers ("MLIM LLC"), The General Partner, has
     procedures in place intended to control market risk exposure, although
     there can be no assurance that they will, in fact, succeed in doing so.
     These procedures focus primarily on monitoring the trading of the Advisors
     selected from time to time by the General Partner of Global Horizons,
     calculating the Net Asset Value of their respective Partnership's accounts
     and Global Horizons' accounts as of the close of business on each day and
     reviewing outstanding positions for over-concentrations both on an
     Advisor-by-Advisor and on an overall Partnership basis. While MLIM LLC does
     not itself intervene in the markets to hedge or diversify the Partnership's
     market exposure, MLIM LLC may urge Advisors to reallocate positions, or
     itself reallocate Partnership assets through Global Horizons among Advisors
     (although typically only as of the end of a month) in an attempt to avoid
     over-concentrations. However, such interventions are unusual. Except in
     cases in which it appears that an Advisor has begun to deviate from past
     practice or trading policies or to be trading erratically, MLIM LLC's basic
     risk control procedures consist simply of the ongoing process of advisor
     monitoring and selection with the market risk controls being applied by the
     Advisors themselves.

     CREDIT RISK

     The risks associated with exchange-traded contracts are typically perceived
     to be less than those associated with over-the-counter
     (non-exchange-traded) transactions, because exchanges typically (but not
     universally) provide clearinghouse arrangements in which the collective
     credit (in some cases limited in amount, in some cases not) of the members
     of the exchange is pledged to support the financial integrity of the
     exchange. In over-the-counter transactions, on the other hand, traders must
     rely solely on the credit of their respective individual counterparties.
     Margins, which may be subject to loss in the event of a default, are
     generally required in exchange trading, and counterparties may require
     margin in the over-the-counter markets.

     The Partnership, through Global Horizons, has credit risk with respect to
     non-performance of its counterparties and brokers, but attempts to mitigate
     this risk by dealing almost exclusively with Merrill Lynch entities as
     clearing brokers.

     The Partnership, through Global Horizons, in its normal course of business,
     enters into various contracts, with Merrill Lynch Pierce Fenner & Smith
     ("MLPF&S") acting as its commodity broker. Pursuant to the brokerage
     agreement with MLPF&S (which includes a netting arrangement), to the extent
     that such trading results in receivables from and payables to MLPF&S, these
     receivables and payables are offset and reported as a net receivable or
     payable in the financial statements of Global Horizons in the Equity in
     commodity futures trading accounts in the Statements of Financial
     Condition.

                                        8
<Page>

Item 2: Management's Discussion and Analysis of Financial Condition and Results
of Operations

                MONTH-END NET ASSET VALUE PER SERIES A 2003 UNIT
<Table>
<Caption>
                          JAN.        FEB.        MAR.
               --------------------------------------------
                                       
                2004     $1.1075     $1.1504    $ 1.1486
</Table>

                 MONTH-END NET ASSET VALUE PER SERIES 2005 UNIT
<Table>
<Caption>
                          JAN.        FEB.        MAR.
               --------------------------------------------
                                       
                2005     $0.9659     $0.9763     $0.9788
</Table>

     Performance Summary

     All of the Partnership's trading assets are invested in Global Horizons.
     The Partnership recognizes trading profits or losses as an investor in
     Global Horizons. The following commentary describes the trading results of
     Global Horizons.

     January 1, 2005 to March 31, 2005

     The Partnership posted a loss for the first quarter. Losses in the currency
     and global equity sectors outweighed gains experienced in the agricultural
     sector.

     The interest rate sector was the best performing sector for the
     Partnership. The Partnership benefited from long U.S. dollar positions
     versus the Euro and long Euro and Japanese fixed incomes. Systematic,
     long-term trend followers also posted gains in the interest rate sector.

     The energy sector was the second highest performing sector for the
     Partnership. Gains were experienced in the energy sector as the Partnership
     benefited from long positions in crude oil and gas as these industries
     profited. Gains were also posted in long crude oil and heating oil
     positions.

     The agricultural sector also performed well for the quarter. Gains were
     experienced from long positions in cattle and hog markets. Short grain
     positions and long soybean positions detracted from performance
     mid-quarter. However, the quarter ended with gains posted due to coffee,
     which experienced a lack of supply and a growing demand.

     The metals sector posted a gain for the quarter. The Partnership benefited
     from long positions in base and precious metals, such as gold, copper and
     zinc.

     The stock indices sector posted a loss for the quarter. Losses occurred in
     the beginning of the quarter due to a trend reversal from long global
     equities to short global equities. Profits were made through long positions
     on the FTSE index and Asian equities. Stock indices contributed negatively
     to performance as the equity markets declined at the end of the quarter.

     The currency sector posted the greatest loss for the Partnership. Losses at
     the beginning of the quarter were due to a trend reversal from short U.S.
     dollar positions to long U.S. dollar positions. Long Japanese yen and Swiss
     franc positions also experienced losses. With the U.S. Federal Reserve
     expressing concern about inflation, investors predicted that interest rates
     and the U.S. dollar would rise. This caused losses as investors fled from
     emerging currencies. Long Australian dollar and Mexican peso positions also
     contributed to negative performance.

                                        9
<Page>

     January 1, 2004 to March 31, 2004

     All of the Partnership's trading assets were invested in MM LLC. The
     Partnership recognizes trading profits or losses as an investor in Global
     Horizons. The following commentary describes the trading results of MM LLC.

     MM LLC experienced gains in the interest rate, metals, agricultural
     commodities, energy, and currency sectors and losses in stock indices.
     Overall, for the quarter, MM LLC experienced gains.

     The interest sector posted the largest gains for the quarter despite choppy
     trading conditions early in the quarter. In January, profits were generated
     from various positions at the short end of the curve in Canada and Europe,
     while losses were posted at longer points in the curve in both the U.S. and
     Europe. In February, fixed income markets resumed their slow upward trend.
     In March, long exposure to most of the major global yield curves proved to
     generate positive results.

     The metals sector posted gains for the quarter as well. In January, both
     precious and industrial metals generated positive returns from the long
     side. Base metals continued to move higher with the exception of nickel.
     Copper rose to its highest price in more than six years due to supply
     disruptions and heavy demand from new home construction. In February, base
     metals continued their upward move as the sector experienced strong demand,
     shrinking supply and U.S. dollar weakness, helping to drive prices higher.
     Strong industrial demand for copper and continued speculative interest
     pushed the market to a seven year high. In March, industrial metals
     generated minor losses for MM LLC, while precious metals contributed
     significantly, particularly, gold and silver.

     The agricultural commodities sector posted gains early in the quarter as
     the USDA cut its forecast of the crop supply for both soybeans and corn,
     which sent prices surging. In February, grain markets extended their
     long-term rally, with corn and soybeans being pushed to highs on strong
     demand and low stockpiles. Grain markets continued to extend their
     long-term rally in March, with corn, soybeans and soymeal being pushed
     higher on strong demand from Asia and lower estimates of supply from South
     America.

     The energy sector posted gains for the quarter. In crude oil and more broad
     energy markets, weather and OPEC were the dominant factors behind price
     moves during January. Weather was extremely cold in the Northeast and
     Midwest U.S., which caused a sharp rally in natural gas and heating oil.
     Crude oil had a sharp rally in early February and gradually sold-off as the
     markets became complacent about the OPEC meeting. The market continued this
     trend, as weather-related demand and tight U.S. inventories continued. In
     March, the energy sectors posted a small loss under extremely volatile
     market conditions. The crude oil market had very choppy performance during
     the month, as did the heating oil market.

     The currency sector posted slight gains for the quarter. The currency
     sector began the quarter with gains as it continued its long trend of a
     weakening U.S. dollar. However, trading was very choppy and gains generated
     in the early part of January were lost. In February and March, the trend
     continued as currency trading was very difficult due to the heightened
     volatility in the markets.

     Stock indices posted losses despite gains early in the quarter. Stock
     indices posted a profit for January, as long exposure to global equities
     from momentum based and fundamental models performed well. In February,
     long exposure to global equities produced positive performance. In March,
     stock indices posted a loss that exceeded the gains from earlier in the
     quarter. Long Nikkei profits were overcome by losses in long exposure to
     European equities, which later flipped to short positions, by month-end.

                                       10
<Page>

     Item 3.   Quantitative and Qualitative Disclosures About Market Risk

     Not applicable

     Item 4. Controls and Procedures

     Merrill Lynch Investment Managers LLC, the General Partner of ML Principal
     Protection L.P., with the participation of the General Partner's Chief
     Executive Officer and the Chief Financial Officer, has evaluated the
     effectiveness of the design and operation of its disclosure controls and
     procedures with respect to the Partnership within 90 days of the filing
     date of this quarterly report, and, based on this evaluation, has concluded
     that these disclosure controls and procedures are effective. Additionally,
     there were no significant changes in the Partnership's internal controls or
     in other factors that could significantly affect these controls subsequent
     to the date of this evaluation, including any corrective actions with
     regard to significant deficiencies and material weaknesses.

                                       11
<Page>

                           PART II - OTHER INFORMATION

Item 1.   Legal Proceedings

     There are no pending legal proceedings to which the Partnership, Global
Horizons, or MLIM LLC is a party.

Item 2.   Changes in Securities and Use of Proceeds

     (a)  None
     (b)  None
     (c)  None
     (d)  None

Item 3.   Defaults Upon Senior Securities

     None.

Item 4.   Submission of Matters to a Vote of Security Holders

     None.

Item 5.   Other Information

     None.

Item 6.   Exhibits and Reports on Form 8-K.

     (a) Exhibits

     There are no exhibits required to be filed with this report.

     (b) Reports on Form 8-K

     There were no reports on Form 8-K filed during the first three months of
fiscal 2005.

                                       12
<Page>

                                   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.


                                        ML PRINCIPAL PROTECTION L.P.

                                        By: MERRILL LYNCH INVESTMENT
                                            MANAGERS LLC
                                               General Partner

<Table>
                                  
Date: May 16, 2005                   By /s/ FABIO P. SAVOLDELLI
                                        -----------------------
                                        Fabio P. Savoldelli
                                        Managing Director and Chief Investment Officer
                                        - Alternative Strategies Division
                                        (Principal Executive Officer)


Date: May 16, 2005                   By /s/ PATRICK HAYWARD
                                        -------------------
                                     Patrick Hayward
                                     Chief Financial Officer
                                     (Principal Financial and Accounting Officer)
</Table>

                                       13