<Page>
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                                 UNITED STATES
                       SECURITIES AND EXCHANGE COMMISSION

                             WASHINGTON, D.C. 20549

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

                                   FORM 10-Q

(MARK ONE)

<Table>
<C>        <S>
   /X/     QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15 (d) OF THE
           SECURITIES EXCHANGE ACT OF 1934

           FOR THE QUARTERLY PERIOD ENDED JUNE 30, 2001
</Table>

                                       OR

<Table>
<C>        <S>
   / /     TRANSITION REPORT PURSUANT TO SECTION 13 OR 15 (d) OF THE
           SECURITIES EXCHANGE ACT OF 1934

           For the transition period from ------------ to ------------
</Table>

                        Commission file number 000-24905

                         BEACON CAPITAL PARTNERS, INC.
             (EXACT NAME OF REGISTRANT AS SPECIFIED IN ITS CHARTER)

<Table>
<S>                                                <C>
                 Maryland                                          04-3403281
------------------------------------------         ------------------------------------------
     (STATE OR OTHER JURISDICTION OF                   (IRS EMPLOYER IDENTIFICATION NO.)
      INCORPORATION OR ORGANIZATION)

     One Federal Street, 26th Floor,
          Boston, Massachusetts                                      02110
------------------------------------------         ------------------------------------------
 (ADDRESS OF PRINCIPAL EXECUTIVE OFFICE)                           (ZIP CODE)

                                        617-457-0400
---------------------------------------------------------------------------------------------
                    (REGISTRANT'S TELEPHONE NUMBER, INCLUDING AREA CODE)
</Table>

    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 __

    Number of Common Shares outstanding at the latest practicable date,
August 10, 2001: 21,730,888 shares, $.01 par value.

--------------------------------------------------------------------------------
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<Page>
                         BEACON CAPITAL PARTNERS, INC.

                                   FORM 10-Q

                                     INDEX

<Table>
<Caption>
                                                                         PAGE
                                                                       --------
<S>      <C>                                                           <C>
Part I--Financial Information

Item 1.  Condensed Consolidated Financial Statements.................         1

         Condensed Consolidated Balance Sheets--June 30, 2001
           (Unaudited) and December 31, 2000.........................         1

         Condensed Consolidated Statements of Operations--Three and
           Six Months Ended June 30, 2001 and 2000 (Unaudited).......         2

         Condensed Consolidated Statements of Cash Flows--Six Months
           Ended June 30, 2001 and 2000 (Unaudited)..................         3

         Notes to Condensed Consolidated Financial Statements........         4

Item 2.  Management's Discussion and Analysis of Financial Condition
           and Results of Operations.................................        10

Item 3.  Quantitative and Qualitative Disclosures about Market
           Risk......................................................        16

Part II--Other Information

Item 1.  Legal Proceedings...........................................        17

Item 2.  Changes in Securities and Use of Proceeds...................        17

Item 3.  Defaults Upon Senior Securities.............................        17

Item 4.  Submission of Matters to a Vote of Security Holders.........        17

Item 5.  Other Information...........................................        17

Item 6.  Exhibits and Reports on Form 8-K............................        17

Exhibit Index........................................................        19
</Table>
<Page>
PART I--FINANCIAL INFORMATION

  ITEM 1. CONDENSED CONSOLIDATED FINANCIAL STATEMENTS

                         BEACON CAPITAL PARTNERS, INC.

                     CONDENSED CONSOLIDATED BALANCE SHEETS

              (DOLLARS IN THOUSANDS, EXCEPT FOR PER SHARE AMOUNTS)

<Table>
<Caption>
                                                               JUNE 30,     DECEMBER 31,
                                                                 2001           2000
                                                              -----------   ------------
                                                              (UNAUDITED)     (NOTE 1)
<S>                                                           <C>           <C>
ASSETS
Real Estate:
  Land......................................................   $   2,890      $  35,264
  Buildings, improvements and equipment.....................      17,874        228,764
                                                               ---------      ---------
                                                                  20,764        264,028
  Less accumulated depreciation.............................       1,635         12,607
                                                               ---------      ---------
                                                                  19,129        251,421

Deferred financing and leasing costs, net of accumulated
  amortization of $570 and $1,421, respectively.............         565          4,396
Cash and cash equivalents...................................     115,295         83,821
Restricted cash.............................................          43            366
Accounts receivable, net....................................       1,866          4,262
Deferred rent receivable....................................         177          2,222
Other assets................................................       1,195          1,504
Investments in partnership, joint ventures and
  corporations..............................................      51,903         55,274
                                                               ---------      ---------
      Total assets..........................................   $ 190,173      $ 403,266
                                                               =========      =========
LIABILITIES AND STOCKHOLDERS' EQUITY
Liabilities:
  Mortgage notes payable....................................   $  25,340      $  30,797
  Note payable--interim financing...........................          --         97,830
  Accounts payable and accrued expenses.....................      22,671         17,205
  Deferred gain on sale of real estate......................      29,079             --
                                                               ---------      ---------
      Total liabilities.....................................      77,090        145,832
                                                               ---------      ---------
Commitments and contingencies...............................          --             --

Minority interest in consolidated partnership...............       1,047          2,544
                                                               ---------      ---------
Stockholders' equity:
  Preferred stock; $.01 par value, 200,000,000 shares
    authorized, none issued or outstanding..................          --             --
  Excess stock; $.01 par value, 250,000,000 shares
    authorized, none issued or outstanding..................          --             --
  Common stock; $.01 par value, 500,000,000 shares
    authorized, 21,730,888 shares issued and outstanding....         217            217
  Additional paid-in capital................................     412,414        412,414
  Cumulative net income.....................................     146,936         95,843
  Cumulative dividends......................................    (447,406)      (251,827)
  Unrealized loss on marketable equity securities...........        (125)        (1,757)
                                                               ---------      ---------
      Total stockholders' equity............................     112,036        254,890
                                                               ---------      ---------
      Total liabilities and stockholders' equity............   $ 190,173      $ 403,266
                                                               =========      =========
</Table>

                            SEE ACCOMPANYING NOTES.

                                       1
<Page>
                         BEACON CAPITAL PARTNERS, INC.

                CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS

              (DOLLARS IN THOUSANDS, EXCEPT FOR PER SHARE AMOUNTS)

                                  (UNAUDITED)

<Table>
<Caption>
                                                         THREE MONTHS ENDED     SIX MONTHS ENDED
                                                              JUNE 30,              JUNE 30,
                                                         -------------------   -------------------
                                                           2001       2000       2001       2000
                                                         --------   --------   --------   --------
<S>                                                      <C>        <C>        <C>        <C>
Revenues:
  Rental income........................................  $  4,168   $  8,524   $11,109    $16,940
  Reimbursement of operating expenses and real estate
    taxes..............................................         7        374       293        690
  Equity in earnings of partnership and joint
    ventures...........................................     2,066      1,120     3,974      3,972
  Interest and dividend income.........................       915      2,039     2,267      3,334
  Gains (losses) on investments, net...................       (14)        --    (2,210)     6,414
  Other income.........................................       137        325       316        581
                                                         --------   --------   -------    -------
      Total revenues...................................     7,279     12,382    15,749     31,931
                                                         --------   --------   -------    -------
Expenses:
  Property operating...................................     1,621      2,510     4,072      4,764
  Real estate taxes....................................       344      1,190     1,248      2,439
  General and administrative...........................     2,974      2,837     9,489      5,764
  Affiliate formation expenses.........................        --         --        --      2,054
  Interest expense.....................................       505        844     1,594      2,484
  Depreciation and amortization........................       949      1,936     2,451      3,801
                                                         --------   --------   -------    -------
      Total expenses...................................     6,393      9,317    18,854     21,306
                                                         --------   --------   -------    -------
Income (loss) before gains (losses) on sales of real
  estate, minority interest and extraordinary items....       886      3,065    (3,105)    10,625
Gains (losses) on sales of real estate.................   (17,107)    58,537    54,727     58,537
                                                         --------   --------   -------    -------
Income (loss) before minority interest and
  extraordinary items..................................   (16,221)    61,602    51,622     69,162
Minority interest in consolidated partnership..........       167     (7,149)     (529)    (8,026)
                                                         --------   --------   -------    -------
Income (loss) before extraordinary items...............   (16,054)    54,453    51,093     61,136
Extraordinary items, net of minority interest..........        --     (4,562)       --     (4,574)
                                                         --------   --------   -------    -------
      Net income (loss)................................  $(16,054)  $ 49,891   $51,093    $56,562
                                                         ========   ========   =======    =======
Income (loss) before extraordinary items per common
  share-basic and diluted..............................  $  (0.74)  $   2.60   $  2.35    $  2.92
Extraordinary items per common share-basic and
  diluted..............................................        --      (0.22)       --      (0.22)
                                                         --------   --------   -------    -------
Net income (loss) per common share-basic and diluted...  $  (0.74)  $   2.38   $  2.35    $  2.70
                                                         ========   ========   =======    =======
Weighted average number of common shares outstanding
  (in thousands).......................................    21,731     20,973    21,731     20,973
                                                         ========   ========   =======    =======
</Table>

                            SEE ACCOMPANYING NOTES.

                                       2
<Page>
                         BEACON CAPITAL PARTNERS, INC.

                CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS

                             (DOLLARS IN THOUSANDS)

                                  (UNAUDITED)

<Table>
<Caption>
                                                                SIX MONTHS ENDED
                                                                    JUNE 30,
                                                              ---------------------
                                                                2001        2000
                                                              ---------   ---------
<S>                                                           <C>         <C>
CASH FLOWS FROM OPERATING ACTIVITIES:
  Net income................................................  $  51,093   $  56,562
  Adjustments to reconcile net income to net cash provided
    by operating activities:
    Depreciation............................................      1,790       2,789
    Amortization............................................        661       1,012
    Extraordinary items, net of minority interest...........         --       4,574
    Gains (losses) on sales of real estate..................    (54,727)    (58,537)
    Equity in earnings of partnership and joint ventures....     (3,974)     (3,972)
    Distributions from partnership and joint venture........      5,999       5,591
    Gains (losses) on investments, net......................      2,210      (6,414)
    Minority interest in consolidated partnership...........        529       8,026
  Increase (decrease) in cash arising from changes in
    operating assets and liabilities:
    Restricted cash.........................................        323         592
    Accounts receivable.....................................      2,018      (1,030)
    Deferred rent receivable................................       (175)       (767)
    Other assets............................................       (436)      1,159
    Accounts payable and accrued expenses...................      5,538      (2,520)
                                                              ---------   ---------
      Net cash provided by operating activities.............     10,849       7,065
                                                              ---------   ---------
CASH FLOWS FROM INVESTING ACTIVITIES:
  Real estate asset acquisitions and improvements...........    (24,944)    (34,443)
  Proceeds from real estate asset sales.....................    344,498      72,085
  Payment of deferred leasing costs.........................       (366)       (584)
  Investments in partnership, joint ventures and
    corporations............................................       (480)     (8,023)
  Distribution from joint venture...........................      3,060      78,519
                                                              ---------   ---------
      Net cash provided by investing activities.............    321,768     107,554
                                                              ---------   ---------
CASH FLOWS FROM FINANCING ACTIVITIES:
  Proceeds from mortgage note...............................     11,500          --
  Repayments on mortgage notes..............................    (16,957)       (153)
  Proceeds from note payable--interim financing.............         --       7,500
  Repayment on note payable--interim financing..............    (97,830)    (32,170)
  Payment of deferred financing costs.......................       (251)       (181)
  Repurchase of common stock................................         --         (18)
  Distribution payments to minority interests...............     (2,026)     (9,637)
  Dividend payments to stockholders.........................   (195,579)    (73,405)
                                                              ---------   ---------
      Net cash used by financing activities.................   (301,143)   (108,064)
                                                              ---------   ---------

Net increase in cash and cash equivalents...................     31,474       6,555
Cash and cash equivalents, beginning of period..............     83,821      76,927
                                                              ---------   ---------
Cash and cash equivalents, end of period....................  $ 115,295   $  83,482
                                                              =========   =========
SUPPLEMENTAL SCHEDULE OF NONCASH INVESTING AND FINANCING
  ACTIVITIES:
Distribution of Cypress stock to minority interests.........  $      --   $   2,073
Dividend of Cypress stock to stockholders...................         --      15,793
Distribution of CO Space stock to minority interests........         --         928
Dividend of CO Space stock to stockholders..................         --       7,065
SUPPLEMENTAL DISCLOSURE:
Cash paid for interest, net of capitalized interest of $580
  and $4,047, respectively..................................  $   2,324   $   3,249
</Table>

                            SEE ACCOMPANYING NOTES.

                                       3
<Page>
                         BEACON CAPITAL PARTNERS, INC.

              NOTES TO CONDENSED CONSOLIDATED FINANCIAL STATEMENTS

                                 JUNE 30, 2001

              (DOLLARS IN THOUSANDS, EXCEPT FOR PER SHARE AMOUNTS)
                                  (UNAUDITED)

1. BASIS OF PRESENTATION

    The financial statements of Beacon Capital Partners, Inc. ("BCP") 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 accounting principles generally accepted in the United
States 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 interim periods are
not necessarily indicative of the results that may be expected for the full
year.

    The balance sheet at December 31, 2000 has been derived from the audited
financial statements at that date but does not include all of the information
and footnotes required by accounting principles generally accepted in the United
States for complete financial statements.

    At June 30, 2001, the Company's investments in marketable equity securities
were included in other assets and had a fair value of approximately $100 and an
unrealized loss of approximately $125. Comprehensive income after giving effect
to the change in the unrealized loss was $50,968 for the six months ended
June 30, 2001. Net income and comprehensive income were the same for the six
months ended June 30, 2000.

    For further information, refer to the consolidated financial statements and
footnotes thereto included in BCP's annual report on Form 10-K for the period
ended December 31, 2000.

2. ORGANIZATION

    Beacon Capital Partners, Inc. was incorporated on January 21, 1998 as a
Massachusetts corporation, and was initially capitalized through loans from the
two founders of BCP, Messrs. Leventhal and Fortin. The loans were repaid in
May 1998. BCP qualifies as a real estate investment trust ("REIT") under the
Internal Revenue Code of 1986, as amended. BCP was established to conduct real
estate investment and development activities and currently operates in one
segment.

    On March 17, 1998, BCP was reincorporated as a Maryland corporation and on
March 20, 1998, BCP completed an initial private offering in accordance with
Section 4(2) of the Securities Act of 1933. BCP initially issued 17,360,769
common shares with proceeds, net of expenses, of $323,110. In April 1998,
3,613,163 additional shares were issued through the exercise of the
underwriter's over-allotment, with proceeds, net of expenses, of $66,620.

    In connection with the reincorporation of BCP in Maryland, BCP established
Beacon Capital Partners, L.P. (the "Operating Partnership"). BCP and the
Operating Partnership are collectively referred to as the "Company". The
Operating Partnership is a Delaware limited partnership. BCP is the sole General
Partner of, and, as of June 30, 2001, holds approximately 99% of the economic
interest in the Operating Partnership. BCP holds an approximate 1% general
partnership interest in the Operating Partnership and the balance is held as a
limited partnership interest. The limited partnership interests not held by BCP
are presented as minority interest in consolidated partnership in the
accompanying condensed consolidated financial statements. On June 24, 1998,
$51,359 in Operating Partnership units were issued to Luddite Associates, an
affiliate of The Prudential Insurance Company of America, in connection with the
purchase of the property known as Technology Square and The Draper Building. On
October 17, 2000, Luddite Associates converted its Operating Partnership units
to common stock of BCP.

                                       4
<Page>
                         BEACON CAPITAL PARTNERS, INC.

        NOTES TO CONDENSED CONSOLIDATED FINANCIAL STATEMENTS (CONTINUED)

                                 JUNE 30, 2001

              (DOLLARS IN THOUSANDS, EXCEPT FOR PER SHARE AMOUNTS)
                                  (UNAUDITED)

2. ORGANIZATION (CONTINUED)
As of June 30, 2001, $4,228 in Operating Partnership units had been issued to
Messrs. Leventhal's and Fortin's family trusts for cash. The term of the
Operating Partnership commenced on March 16, 1998 and shall continue until
January 1, 2056 or until such time as a Liquidating Event, as defined, has
occurred.

    On April 4, 2001, the Company adopted, and the shareholders approved an
asset sale plan (the "Asset Sale Plan") which will permit the Company to sell,
transfer or exchange all or substantially all of its assets.

3. REAL ESTATE

    In September 2000, the Company commenced the sales of the Fort Point Place
residential condominiums and as of June 30, 2001, 112 of the 120 units have been
sold. On February 9, 2001, the Company sold Technology Square, a property
consisting of existing buildings, buildings under development and permitted land
for additional development for approximately $278,785. The Company will continue
to oversee the development and the buyer will fund the remaining development
costs for the new buildings. Under the terms of the purchase and sale agreement,
in order to avoid financial penalties, the Company is required to complete the
construction of the new buildings by specific dates and within budget. The
development is scheduled to be completed in the third quarter of 2002. As of
June 30, 2001, the Company recognized a gain on the sale of approximately
$77,789. Pursuant to the applicable accounting rules, an additional gain
estimated at approximately $29,079 has been deferred and is expected to be
realized in future periods as construction is completed. In June 2001, in two
separate transactions, the Company sold 12 of the 14 properties in the Dallas
Office and Industrial Portfolio for $63,300 and recognized an aggregate loss of
approximately $24,002 on the transactions. On July 10, 2001, the Company sold
the two Fort Point Place office buildings for $29,500. The Fort Point Place
office buildings had a net book value of approximately $11,238 at June 30, 2001
and the Company will recognize a gain on the transaction.

4. INVESTMENTS IN PARTNERSHIP, JOINT VENTURES AND CORPORATIONS

    The investments in partnership, joint ventures and corporations represent
the Company's interest in (i) a joint venture with PW Acquisitions IX, LLC,
known as Beacon/PW Kendall LLC ("The Athenaeum Portfolio"), (ii) a joint venture
with Mathilda Partners LLC ("Mathilda Research Centre"), (iii) a joint venture
with Mathilda Partners II LLC ("Mathilda Research Centre II"), (iv) a joint
venture with HA L.L.C. ("Millennium Tower"), and (v) an investment in Beacon
Capital Strategic Partners, L.P. ("BCSP").

                                       5
<Page>
                         BEACON CAPITAL PARTNERS, INC.

        NOTES TO CONDENSED CONSOLIDATED FINANCIAL STATEMENTS (CONTINUED)

                                 JUNE 30, 2001

              (DOLLARS IN THOUSANDS, EXCEPT FOR PER SHARE AMOUNTS)
                                  (UNAUDITED)

4. INVESTMENTS IN PARTNERSHIP, JOINT VENTURES AND CORPORATIONS (CONTINUED)
    A reconciliation of the underlying net assets to the Company's carrying
value of investments in partnership, joint ventures and corporations is as
follows:

<Table>
<Caption>
                                           THE      MATHILDA    MATHILDA
                                        ATHENAEUM   RESEARCH    RESEARCH    MILLENNIUM
                                        PORTFOLIO    CENTRE    CENTRE II      TOWER        BCSP       TOTAL
                                        ---------   --------   ----------   ----------   --------   ---------
<S>                                     <C>         <C>        <C>          <C>          <C>        <C>
Operating Partnership equity interest
  (including accumulated earnings,
  net of distributions)..............   $    221    $16,405      $7,568      $19,754     $  1,817   $  45,765
Other costs..........................         --      2,504         506        3,032           96       6,138
                                        --------    -------      ------      -------     --------   ---------
Carrying value of investments in
  partnership, joint ventures and
  corporations at June 30, 2001......   $    221    $18,909      $8,074      $22,786     $  1,913   $  51,903
                                        ========    =======      ======      =======     ========   =========
Equity in earnings of partnership and
  joint ventures
Six months ended
  June 30, 2001......................   $     --    $ 2,097      $   --      $   754     $  1,123   $   3,974
  June 30, 2000......................      1,753        (91)         --           --        2,310       3,972
Operating Partnership share of gains
  on sales of real estate
Six months ended
  June 30, 2001......................   $     --    $    --      $   --      $    --     $    940   $     940
  June 30, 2000......................     12,618         --          --           --       18,597      31,215
Operating Partnership share of
  extraordinary items
Six months ended
  June 30, 2001......................   $     --    $    --      $   --      $    --     $     --   $      --
  June 30, 2000......................     (5,149)        --          --           --          (25)     (5,174)
</Table>

THE ATHENAEUM PORTFOLIO

    In 1998, Beacon/PW Kendall LLC, a joint venture of the Company and PW
Acquisitions IX, LLC, an affiliate of PaineWebber, purchased The Athenaeum
Portfolio, an 11 building 970,000 square foot mixed-use portfolio located in
Cambridge, Massachusetts. In 2000, in two separate transactions, the joint
venture sold The Athenaeum Portfolio and recognized an aggregate gain on the
sales of approximately $64,865, of which the Company's share was approximately
$32,432.

MATHILDA RESEARCH CENTRE

    On August 9, 1998, the Company entered into a joint venture agreement with
Mathilda Partners LLC, an affiliate of Menlo Equities, a California based
developer, to develop two four-story Class A office/R&D buildings with surface
parking in Sunnyvale, California, known as Mathilda Research Centre. The Company
and Mathilda Partners LLC have agreed to fund 87.5% and 12.5% of the equity
required, respectively. On November 4, 1998, the venture acquired a twelve-acre
site on Mathilda Avenue in Sunnyvale, CA, on which it developed Mathilda
Research Centre. The first building (approximately 144,000 square feet) was
completed in June 2000 and the second building (approximately 123,000 square

                                       6
<Page>
                         BEACON CAPITAL PARTNERS, INC.

        NOTES TO CONDENSED CONSOLIDATED FINANCIAL STATEMENTS (CONTINUED)

                                 JUNE 30, 2001

              (DOLLARS IN THOUSANDS, EXCEPT FOR PER SHARE AMOUNTS)
                                  (UNAUDITED)

4. INVESTMENTS IN PARTNERSHIP, JOINT VENTURES AND CORPORATIONS (CONTINUED)
feet) was completed in March 2001. Both buildings are leased to Juniper
Networks, Inc. ("Juniper Networks"). The estimated cost of the 267,000 square
foot development was approximately $64,000. The joint venture has obtained a
$44,000 construction loan from an institutional lender to finance the
development, and the balance of the development costs have been funded by equity
contributions from the venturers. As of June 30, 2001, the venturers have funded
equity contributions of $20,000, of which the Company's portion was $17,500.

MATHILDA RESEARCH CENTRE II

    On August 9, 2000, the Company entered into a joint venture agreement with
Mathilda Partners II LLC, an affiliate of Menlo Equities, a California based
developer, to develop an additional phase of Mathilda Research Centre in
Sunnyvale, California, also for Juniper Networks. The Company and Mathilda
Partners II LLC have agreed to fund 87.5% and 12.5% of the equity required,
respectively. On November 30, 2000, the joint venture acquired a parcel of land
at 1220 N. Mathilda Avenue in Sunnyvale, California on which it is developing
the additional phase of Mathilda Research Centre. The estimated cost of the
proposed 158,000 square foot building is approximately $40,650. The project will
be funded from equity contributions of approximately $8,040, of which the
Company's portion will be approximately $7,035, and a $32,610 construction loan
from an institutional lender. As of June 30, 2001, the members had funded equity
contributions of approximately $8,650, of which the Company's portion was
approximately $7,568. The Company currently expects a distribution of
approximately $533, representing its excess contributions, from loan proceeds
when certain conditions are met.

MILLENNIUM TOWER

    On September 1, 1998 the Company entered into a joint venture agreement with
HA L.L.C., an affiliate of Martin Smith Real Estate Services, a Seattle based
real estate company, to develop a 20-story office/retail and residential tower
in downtown Seattle, Washington, known as Millennium Tower. The Company and HA
L.L.C. have agreed to fund 66 2/3% and 33 1/3% of the equity required,
respectively. Land was contributed to the joint venture by HA L.L.C. at an
agreed value of $10,500, and the Company agreed to fund the first $19,000 of
cash requirements for the venture. As of June 30, 2001, the Company has funded
its total commitment of $19,000. The joint venture has obtained a $45,000
construction loan from two institutional lenders to finance the balance of the
development costs. The estimated cost of the project is $72,000, including the
value of the land.

    The Company's residential portion of this investment is held by BCP
Millennium Residential, Inc., a Massachusetts corporation ("BCP Millennium
Residential"). Prior to March 2001, in order to comply with certain rules
applicable to REITs, the voting common stock of BCP Millennium Residential was
controlled by Messrs. Leventhal and Fortin. In March 2001, BCP Millennium
Residential was converted to a taxable REIT subsidiary and Messrs. Leventhal and
Fortin transferred their ownership to the Company. The Company owns 100% of the
economic interests in BCP Millennium Residential and for financial statement
presentation purposes, the Company consolidates BCP Millennium Residential.

                                       7
<Page>
                         BEACON CAPITAL PARTNERS, INC.

        NOTES TO CONDENSED CONSOLIDATED FINANCIAL STATEMENTS (CONTINUED)

                                 JUNE 30, 2001

              (DOLLARS IN THOUSANDS, EXCEPT FOR PER SHARE AMOUNTS)
                                  (UNAUDITED)

4. INVESTMENTS IN PARTNERSHIP, JOINT VENTURES AND CORPORATIONS (CONTINUED)
BCSP

    On October 1, 1999, the Company completed the initial closing for BCSP, a
real estate limited partnership, of which BCP Strategic Partners LLC, the
Company's wholly-owned subsidiary, is the General Partner. Subsequent to
October 1, 1999, the Company completed additional closings and as of March 28,
2000 (the BCSP final closing date), equity commitments totaled $287,500, of
which the Company's equity commitment was $57,500. The commitments include
investments from various endowments, foundations, pension funds and other
institutional investors. For a period of up to two years from October 1, 1999,
BCSP will be the Company's exclusive real estate investment vehicle. As of
June 30, 2001, the Company has funded approximately $3,200 of its committed
investment. In connection with the formation of BCSP, for the six months ended
June 30, 2000, the Company incurred affiliate formation expenses of
approximately $2,054. The expenses consist of underwriter commissions and fees
for legal and professional services not reimbursed by the partners of BCSP.

    On March 17, 2000, BCSP obtained a $137,500 secured revolving credit
facility. On June 14, 2000, BCSP sold 233 Fremont Street, a property located in
San Francisco, California that was undergoing redevelopment. The property was
sold for approximately $145,894, including approximately $15,894 held in escrow
pending completion of the property's redevelopment. A portion of the escrow
funds were subsequently expended. BCSP oversaw the redevelopment and the buyer
funded the remaining redevelopment costs. The redevelopment was substantially
completed in the second quarter of 2001. For the six months ended June 30, 2001
and the year ended December 31, 2000, BCSP recognized a gain on the sale of
approximately $2,960 and $71,643, respectively. Pursuant to the applicable
accounting rules, additional gain has been deferred by BCSP until future
periods, pending receipt of final invoices from contractors and resolution of
certain contingencies. The Company's share of the recognized gain for the six
months ended June 30, 2001 and the year ended December 31, 2000 was
approximately $940 and $25,736, respectively. On June 28, 2000, BCSP distributed
$70,000 of the sale proceeds, of which the Company's share was approximately
$25,169.

5. MORTGAGE NOTES PAYABLE

    The mortgage notes payable, collateralized by certain properties and
assignments of leases, total $25,340 at June 30, 2001. A mortgage note payable
in the amount of approximately $1,374 has a fixed interest rate of 9.0% and
matures in 2017. A variable rate mortgage note payable in the amount of
approximately $23,966 has a current interest rate of approximately 6.16% at
June 30, 2001 and matures in May 2003. The net book value of the mortgaged
assets is approximately $14,468 at June 30, 2001.

    Future minimum principal payments due during the next five years and
thereafter are as follows:

<Table>
<S>                                                           <C>
2001........................................................  $    23
2002........................................................       42
2003........................................................   24,012
2004........................................................       51
2005........................................................       55
Thereafter..................................................    1,157
                                                              -------
Total                                                         $25,340
                                                              =======
</Table>

                                       8
<Page>
                         BEACON CAPITAL PARTNERS, INC.

        NOTES TO CONDENSED CONSOLIDATED FINANCIAL STATEMENTS (CONTINUED)

                                 JUNE 30, 2001

              (DOLLARS IN THOUSANDS, EXCEPT FOR PER SHARE AMOUNTS)
                                  (UNAUDITED)

5. MORTGAGE NOTES PAYABLE (CONTINUED)
    On July 10, 2001, in conjunction with the sale of the Fort Point Place
office buildings, the variable rate mortgage payable in the amount of
approximately $23,966 was paid off.

6. NOTE PAYABLE--INTERIM FINANCING

    On June 28, 1999, the Company obtained $100,000 of secured interim financing
(the "Interim Financing") from Bankers Trust Company. On December 3, 1999, the
Company executed an amendment to the Interim Financing that increased the loan
amount to $130,000. The Draper Building, which was sold on April 19, 2000, was
part of the collateral for the Interim Financing and as a condition of the
property's release, the Interim Financing was paid down by approximately
$32,170. The Interim Financing matured in June 2000 and pursuant to the terms of
the note, the Company exercised its option to extend the maturity date to June
2001. On February 9, 2001, in conjunction with the sale of Technology Square,
the Interim Financing was paid off.

                                       9
<Page>
ITEM 2. MANAGEMENT'S DISCUSSION AND ANALYSIS OF FINANCIAL CONDITION AND RESULTS
  OF OPERATIONS.

OVERVIEW

    This Form 10-Q contains forward-looking statements within the meaning of
Section 27A of the Securities Act of 1933 and Section 21E of the Securities
Exchange Act of 1934. The words "believe", "expect", "anticipate", "intend",
"estimate" and other expressions which are predictions of or indicate future
events and trends and which do not relate to historical matters identify
forward-looking statements. Our actual results could differ materially from
those set forth in the forward-looking statements. Certain factors that might
cause such a difference include the following: the ability to sell properties
under the Asset Sale Plan; real estate investment considerations, such as the
effect of economic and other conditions in the market area on cash flows and
values; the need to renew leases or relet space upon the expiration of current
leases, the need to lease new developments and redevelopments and the ability of
a property to generate revenue sufficient to meet debt service payments and
other operating expenses; risks associated with borrowing, such as the
possibility that we will not have sufficient funds available to make principal
payments on outstanding debt and outstanding debt may be refinanced at higher
interest rates or otherwise on terms less favorable to us; the impact of pending
or future litigation; variations in quarterly operating results; securities held
for investment are subject to fluctuations in valuation based upon the
performance of the underlying businesses; risks that some of our investments
could cause us to fail to qualify as a REIT; and those risks and uncertainties
contained elsewhere in this report, in our Proxy Statement relating to the
adoption of the Asset Sale Plan, and under the heading "Risk Factors" beginning
on page 9 of our Form 10-K as filed with the Securities and Exchange Commission
on March 23, 2001.

    The following discussion and analysis of the financial condition and results
of operations should be read in conjunction with the accompanying consolidated
financial statements and notes thereto.

RESULTS OF OPERATIONS

    SUMMARY

    Changes in revenues and expenses for the six months ended June 30, 2001 and
2000 were primarily due to the timing of investment, financing and sale
transactions and redevelopment and releasing programs during 2000 and 2001. The
Technology Square Building 300 development commenced in January 2000; The
Athenaeum Portfolio was refinanced in April 2000; The Draper Building was sold
in April 2000; the Interim Financing was paid down by $32.2 million in April
2000; some of the assets in The Athenaeum Portfolio (215 First Street, 195 First
Street and Doc Linskey Way) were sold in June 2000; BCSP sold 233 Fremont Street
in June 2000; the first building in Mathilda Research Centre was completed in
June 2000; the repurchase of common stock of BCP and certain voting trust
interests in accordance with the share repurchase program occurred in July 2000;
the development of Technology Square Buildings 600 and 700 commenced in August
2000; additional Wyndham preferred stock was distributed in November 2000;
$3.2 million of capital was contributed to BCSP in December 2000; the remaining
assets in The Athenaeum Portfolio (One Kendall Square) were sold in December
2000; Technology Square was sold in February 2001; the Interim Financing was
paid off in February 2001; cash dividends totaling $9.00 per share were paid in
the first six months of 2001; the second building in Mathilda Research Centre
was completed in the first quarter of 2001; the office portion of Millennium
Tower was completed in the first quarter of 2001; the marketing and sales of
Millennium Tower residential condominiums commenced in the first quarter of
2001; our shareholders adopted the Asset Sale Plan in April 2001 which
authorizes us to sell, transfer or exchange all or substantially all of our
assets; the Fort Point Place loan was increased in May 2001; 12 of the 14
properties of the Dallas Office and Industrial Portfolio were sold in
June 2001; the Fort Point Place office buildings were sold in July 2001; and a
cash dividend of $1.00 per share was paid in July 2001.

                                       10
<Page>
COMPARISON OF THE THREE MONTHS ENDED JUNE 30, 2001 AND 2000

    Total revenues were $7.3 million and $12.4 million for the three months
ended June 30, 2001 and 2000, respectively. Rental income was $4.2 million and
$8.5 million for the three months ended June 30, 2001 and 2000, respectively.
The decrease of $4.3 million was due to the sales of the Technology Square and
12 of the 14 properties of the Dallas Office and Industrial Portfolio offset by
increased rents in Fort Point Place. Reimbursement of operating expenses and
real estate taxes was $0.0 million and $0.4 million for the three months ended
June 30, 2001 and 2000, respectively. The decrease of $0.4 million was due to
decreased real estate tax reimbursements in the Dallas Office and Industrial
Portfolio. Equity in earnings of partnership and joint ventures was
$2.1 million and $1.1 million for the three months ended June 30, 2001 and 2000,
respectively. The increase of $1.0 million was due to earnings from Mathilda
Research Centre and Millennium Tower offset by decreased earnings due to the
sale of The Athenaeum Portfolio. Interest and dividend income was $0.9 million
and $2.1 million for the three months ended June 30, 2001 and 2000,
respectively. The decrease of $1.2 million was due to reduced interest earned
from cash on hand and Wyndham dividends received in 2000. Other income was
$0.1 million and $0.3 million for the three months ended June 30, 2001 and 2000,
respectively. The decrease of $0.2 million was due to management fees received
from The Athenaeum Portfolio in 2000.

    Total expenses were $6.4 million and $9.3 million for the three months ended
June 30, 2001 and 2000, respectively. Property operating expenses were
$1.6 million and $2.5 million for the three months ended June 30, 2001 and 2000,
respectively. The decrease of $0.9 million was primarily due to the sale of
Technology Square. Real estate taxes were $0.3 million and $1.2 million for the
three months ended June 30, 2001 and 2000, respectively. The decrease of
$0.9 million was due to the sale of Technology Square and lower estimated taxes
for the Dallas Office and Industrial Portfolio. General and administrative
expenses were $3.0 million and $2.8 million for the three months ended June 30,
2001 and 2000, respectively. Interest expense was $0.5 million and $0.9 million
for the three months ended June 30, 2001 and 2000, respectively. The decrease of
$0.4 million was due to interest on the Interim Financing offset by capitalized
interest. Depreciation and amortization was $1.0 million and $1.9 million for
the three months ended June 30, 2001 and 2000, respectively. The decrease of
$0.9 million was primarily due to the sale of Technology Square.

    The losses on sales of real estate for the three months ended June 30, 2001
of $17.1 million resulted from the losses from the sales of 12 of the 14
properties of the Dallas Office and Industrial Portfolio of $24.0 million offset
by the additional recognized gain from the sale of Technology Square of
$6.5 million and our share of the additional recognized gain on the sale of 233
Fremont Street of $0.4 million. The gains on sales of real estate for the three
months ended June 30, 2000 of $58.5 million resulted from the sale of The Draper
Building of $27.3 million, our share of the gain on the sale of some of the
assets of The Athenaeum Portfolio of $12.6 million and our share of the
recognized gain on the sale of 233 Fremont Street of $18.6 million. The minority
interest in consolidated partnership of $0.2 and ($7.1) million for the three
months ended June 30, 2001 and 2000, respectively, represent the portion of the
Operating Partnership that is not owned by BCP. The extraordinary items, net of
minority interest of ($4.6) million for the three months ended June 30, 2000 are
primarily due to our share of the write-off of transaction costs and unamortized
deferred financing costs as a result of the refinancing of The Athenaeum
Portfolio.

COMPARISON OF THE SIX MONTHS ENDED JUNE 30, 2001 AND 2000

    Total revenues were $15.7 million and $31.9 million for the six months ended
June 30, 2001 and 2000, respectively. Rental income was $11.1 million and
$16.9 million for the six months ended June 30, 2001 and 2000, respectively. The
decrease of $5.8 million was due to the sales of Technology Square and 12 of the
14 properties of the Dallas Office and Industrial Portfolio offset by increased
rents in Fort Point Place. Reimbursement of operating expenses and real estate
taxes was $0.3 million and $0.7 million for the six months ended June 30, 2001
and 2000, respectively. The decrease of $0.4 million was due to decreased real
estate tax reimbursements in the Dallas Office and Industrial Portfolio. Equity
in earnings of partnership

                                       11
<Page>
and joint ventures was flat at $4.0 million for the six months ended June 30,
2001 and 2000. The composition of the amounts from year to year was different
due to 2001 increased earnings from Mathilda Research Centre and Millennium
Tower and reduced earnings from BCSP and The Athenaeum Portfolio. Interest and
dividend income was $2.2 million and $3.3 million for the six months ended
June 30, 2001 and 2000, respectively. The decrease of $1.1 million was due to
Wyndham dividends received in 2000 and reduced interest earned from cash on
hand. Gains (losses) on investments were ($2.2) million and $6.4 million for the
six months ended June 30, 2001 and 2000, respectively. The decrease of
$8.6 million was due to the Cypress gain recognized in 2000 and Cypress and CO
Space losses recognized in 2001. Other income was $0.3 million and $0.6 million
for the six months ended June 30, 2001 and 2000, respectively. The decrease of
$0.3 million was due to management fees received from The Athenaeum Portfolio in
2000.

    Total expenses were $18.8 million and $21.3 million for the six months ended
June 30, 2001 and 2000, respectively. Property operating expenses were
$4.1 million and $4.8 million for the six months ended June 30, 2001 and 2000,
respectively. The decrease of $0.7 million was primarily due to the sale of
Technology Square. Real estate taxes were $1.2 million and $2.4 million for the
six months ended June 30, 2001 and 2000, respectively. The decrease of
$1.2 million was due to the sale of Technology Square and lower estimated taxes
for the Dallas Office and Industrial Portfolio. General and administrative
expenses were $9.5 million and $5.8 million for the six months ended June 30,
2001 and 2000, respectively. The increase of $3.7 million was primarily due to
management personnel bonuses for 2000 achievements that were expensed and paid
in 2001. Affiliate formation expenses were $2.0 million for the six months ended
June 30, 2000. Affiliate formation expenses were costs incurred in the formation
of BCSP and consist of underwriter commissions and fees for legal and
professional services not reimbursed by the partners of BCSP. Interest expense
was $1.6 million and $2.5 million for the six months ended June 30, 2001 and
2000, respectively. The decrease of $0.9 million was due to interest on the
Interim Financing offset by capitalized interest. Depreciation and amortization
was $2.4 million and $3.8 million for the six months ended June 30, 2001 and
2000, respectively. The decrease of $1.4 million was primarily due to the sale
of Technology Square.

    The gains on sales of real estate for the six months ended June 30, 2001 of
$54.7 million resulted from the recognized gain from the sale of Technology
Square of $77.8 million and our share of the additional recognized gain on the
sale of 233 Fremont Street of $0.9 million, offset by the losses from the sales
of 12 of the 14 properties of the Dallas Office and Industrial Portfolio of
$24.0 million. The gains on sales of real estate for the six months ended
June 30, 2000 of $58.5 million resulted from the sale of The Draper Building of
$27.3 million, our share of the gain on the sale of some of the assets of The
Athenaeum Portfolio of $12.6 million and our share of the recognized gain on the
sale of 233 Fremont Street of $18.6 million. The minority interest in
consolidated partnership of ($0.5) and ($8.0) million for the six months ended
June 30, 2001 and 2000, respectively, represent the portion of the Operating
Partnership that is not owned by BCP. The extraordinary items, net of minority
interest of ($4.6) million for the six months ended June 30, 2000 are primarily
due to our share of the write-off of transaction costs and unamortized deferred
financing costs as a result of the refinancing of The Athenaeum Portfolio.

FUTURE RESULTS OF OPERATIONS

    We anticipate that results in future periods will be impacted by future
dispositions if any, that are authorized under the Asset Sale Plan. Rental
income will decline as a result of the sales of Technology Square in
February 2001, 12 of the 14 properties in the Dallas Office and Industrial
Portfolio in June 2001 and the Fort Point Place office buildings in July 2001
and future sales that may occur under the Asset Sale Plan. Equity in earnings of
partnership and joint ventures may increase due to the completion and lease up
of Mathilda Research Centre and Millennium Tower, until such time that they are
disposed of under the Asset Sale Plan. Property operating and related expenses
are also expected to decline as a result of the sales of properties and the
associated payoff of debt and future sales expected under the Asset Sale Plan.

                                       12
<Page>
We are currently marketing the remaining two properties in the Dallas Office and
Industrial Portfolio. Any additional sales transactions may result in losses.

    Under the new management incentive plan adopted in 2000, members of
management will be entitled to participate in all returns realized by the
Company after specified benchmarks are achieved. To the extent that return
hurdles are achieved, we will record an allocation of earnings as a minority
interest charge in amounts that could be material. In addition, we intend to
retain assets in amounts sufficient to fund amounts owed to the minority
interest unitholders.

LIQUIDITY AND CAPITAL RESOURCES

    Cash and cash equivalents were $115.3 million at June 30, 2001 as compared
to $83.8 million at December 31, 2000. The increase of $31.5 million was
primarily the result of (i) proceeds from the sales of Technology Square and 12
of the 14 properties of the Dallas Office and Industrial Portfolio,
(ii) proceeds from the increase in the Fort Point Place mortgage note payable,
and (iii) cash flow from operations, all offset by (i) the payments of the
January 2001, March 2001 and May 2001 dividends to stockholders and
distributions to unitholders, (ii) the payoff of the Interim Financing,
(iii) the payoff of some of the Dallas Office and Industrial Portfolio mortgage
notes payable, and (iv) the payment of Technology Square development costs.
Subsequent to June 30, 2001, we paid a dividend to stockholders and a
distribution to unitholders of approximately $22.0 million.

SHORT AND LONG-TERM LIQUIDITY

    We have considered our short-term (up to 12 months) liquidity needs and the
adequacy of expected liquidity sources to meet these needs. We believe that our
principal short-term operating liquidity needs are to fund normal recurring
expenses, debt service requirements and the minimum distribution required to
maintain the Company's REIT qualification under the Internal Revenue Code of
1986, as amended. We believe that these needs will be provided for by cash flow
from operating activities, sales of assets and current cash balances. We believe
that our 2001 distribution requirement to maintain our REIT qualification will
be met from our 2001 cash distributions to date of $10.00 per share of common
stock of BCP (including the July 2001 distribution) and from future
distributions expected from the implementation of the Asset Sale Plan. We
believe our other short-term liquidity needs are the funding of BCSP capital
commitments, the completion of current development projects and funding of the
management incentive plan. We expect to fund these needs from current cash
balances, mortgages and other debt instruments, and through sales of assets.

    We expect to meet long-term (greater than 12 months) liquidity requirements
for the completion of current development projects, scheduled debt maturities,
other non-recurring capital improvements and funding of the management incentive
plan through sales of assets, indebtedness, and from current cash balances.

CAPITALIZATION

    As of June 30, 2001, our total consolidated debt was approximately
$25.4 million and our total consolidated debt plus our proportionate share of
total unconsolidated debt was approximately $112.9 million. The following table
sets forth certain information regarding our consolidated and unconsolidated
debt obligations, including obligations relating to specific properties. We have
not entered into any hedging transactions and the variable interest rates
reflected in the table are the weighted averages of the outstanding loan layers.
All of the debt is non-recourse to us, with certain exceptions such as liability
for fraud, misapplication of insurance proceeds, environmental matters and
certain guarantees for completion of construction.

                                       13
<Page>

<Table>
<Caption>
                                                                       CURRENT
                                                                       INTEREST
                                                         COMPANY'S     RATE AT
                                            PRINCIPAL     PORTION      JUNE 30,   MATURITY        PREPAYMENT
DEBT                                         AMOUNT     OF PRINCIPAL     2001       DATE          PROVISIONS
----                                        ---------   ------------   --------   --------       -------------
                                             (DOLLARS IN MILLIONS)
<S>                                         <C>         <C>            <C>        <C>            <C>
CONSOLIDATED DEBT
FIXED RATE:

DALLAS OFFICE AND INDUSTRIAL PORTFOLIO:

Plaza at Walnut Hill......................   $  1.4        $  1.4         9.00%           (a)    Prepayable
                                            -------      --------       ------                   subject to
                                                                                                 conditions(b)

Subtotal / Weighted Average

  Fixed Rate Debt.........................      1.4           1.4         9.00%
                                             ------        ------       ------

VARIABLE RATE:

Fort Point Place..........................     24.0          24.0         6.16%    5/10/03       Prepayable
                                            -------      --------       ------                   subject to
                                                                                                 conditions(c)

Subtotal / Weighted Average
  Variable Rate Debt......................     24.0          24.0         6.16%
                                             ------        ------       ------

Subtotal / Weighted Average
  Consolidated Debt.......................     25.4          25.4         6.32%
                                             ------        ------       ------

UNCONSOLIDATED DEBT
VARIABLE RATE:

Beacon Capital Strategic                       87.7          17.5         4.71%
  Partners, L.P. (d)......................                                                (d)    Prepayable
                                                                                                 subject to
                                                                                                 conditions(c)

Mathilda Research Centre I................     44.0          38.5         6.57%   10/25/02       Prepayable
                                                                                                 subject to
                                                                                                 conditions(c)

Mathilda Research Centre II...............      9.9           8.7         6.58%   12/29/03       Prepayable
                                                                                                 subject to
                                                                                                 conditions(c)

Millennium Tower..........................     34.1          22.8         6.31%           (e)    Prepayable
                                            -------      --------       ------                   subject to
                                                                                                 conditions(c)

Subtotal / Weighted Average
  Unconsolidated Debt.....................    175.7          87.5         6.13%
                                             ------        ------       ------

Total / Weighted Average..................   $201.1        $112.9         6.17%
                                             ======        ======       ======
</Table>

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

 (a) Plaza at Walnut Hill loan matures on July 1, 2017. The lender has the right
     to accelerate the maturity in the sixth, eleventh or sixteenth loan years,
     on six months' notice. No prepayment penalties apply in that event.

 (b) Currently prepayable subject to a yield maintenance payment based on the
     rate of United States Treasury Notes having a term closest to the date of
     maturity but in no event less than 1% of the then balance.

 (c) Prepayable any time in whole or in part subject to payment of applicable
     breakage costs and in some cases fees.

 (d) Includes a subscription line and a construction loan with varying maturity
     dates.

 (e) The Millennium Tower loan matures on June 1, 2002. The loan may be extended
     for one year if certain conditions are met.

                                       14
<Page>
    The following table, which includes both consolidated and unconsolidated
debt, summarizes the scheduled amortization of principal and maturities of the
loans outstanding as of June 30, 2001.

<Table>
<Caption>
                                               SCHEDULED
                                              AMORTIZATION   MATURITIES    TOTAL
                                              ------------   ----------   --------
                                                     (DOLLARS IN THOUSANDS)
<S>                                           <C>            <C>          <C>
July 1, 2001 - December 31, 2001............     $   23       $ 16,500    $ 16,523
2002........................................         42         62,361      62,403
2003........................................         46         32,665      32,711
2004........................................         51             --          51
2005........................................         55             --          55
Thereafter..................................      1,157             --       1,157
                                                 ------       --------    --------
  Total.....................................     $1,374       $111,526    $112,900
                                                 ======       ========    ========
</Table>

FUNDS FROM OPERATIONS

    Due to our implementation of the Asset Sale Plan that was approved by our
shareholders and adopted in April 2001, we believe that FFO is not a relevant
measurement of BCP's 2001 financial results.

PROPERTY INFORMATION

    The following table sets forth the Total Area, the Percentage Leased, the
Average Base Rent (as defined below) and the Average Net Effective Rent (as
defined below) per square foot for each of the properties we owned or had an
interest in (excluding properties controlled by BCSP) as of June 30, 2001. Base
Rent is gross rent excluding payments by tenants on account of real estate taxes
and operating expense escalation charges. Net Effective Rent is Base Rent
adjusted on a straight-line basis for contractual rent step-ups and free rent
periods, plus tenant payments on account of real estate tax and operating
expense escalation charges, less total operating expenses and real estate taxes.

<Table>
<Caption>
                                                                                     AVERAGE    AVERAGE
                                                                TOTAL        %         BASE     NET EFF
PROPERTY                                                        AREA       LEASED      RENT       RENT
--------                                                      ---------   --------   --------   --------
<S>                                                           <C>         <C>        <C>        <C>
SOUTH BOSTON, MA:
Fort Point Place (1)........................................    145,222      93%      $32.89     $26.48
                                                              ---------     ----      ------     ------
  Subtotal / Weighted Average South Boston, MA..............    145,222      93%       32.89      26.48
                                                              ---------     ----      ------     ------
SUBURBAN DALLAS, TX:
R&D / INDUSTRIAL
Plaza at Walnut Hill........................................     88,280      89%        8.84       8.33
Venture Drive Tech Center...................................    128,322      60%        5.08       3.67
                                                              ---------     ----      ------     ------
  Subtotal / Weighted Average Suburban Dallas, TX...........    216,602      72%        6.97       6.01
                                                              ---------     ----      ------     ------
SEATTLE, WA:
Millennium Tower (2)........................................    199,384      81%       33.32      36.37
                                                              ---------     ----      ------     ------
  Subtotal / Weighted Average Seattle, WA...................    199,384      81%       33.32      36.37
                                                              ---------     ----      ------     ------
SUNNYVALE, CA:
Mathilda Research Centre (3)................................    266,750     100%       30.98      37.69
                                                              ---------     ----      ------     ------
  Subtotal / Weighted Average Sunnyvale, CA.................    266,750     100%       30.98      37.69
                                                              ---------     ----      ------     ------
  Total / Weighted Average Properties.......................    827,958      87%      $26.66     $28.42
                                                              =========     ====      ======     ======
</Table>

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

(1) Fort Point Place includes two additional buildings that are not included in
    these figures. The two buildings consist of approximately 137,000 square
    feet of recently converted residential condominiums. We are currently in the
    process of selling the condominiums. As of June 30, 2001, 112 of the 120
    units have been sold.

(2) We own Millennium Tower with our joint venture partner, HA L.L.C., an
    affiliate of Martin Smith Real Estate Services. Millennium Tower leases are
    NNN leases. Millennium Tower includes approximately 61,000 square feet

                                       15
<Page>
    of residential condominiums. The joint venture is currently marketing the
    condominiums for sale and as of June 30, 2001, 2 of the 20 units have been
    sold.

(3) We own Mathilda Research Centre with our joint venture partner, Mathilda
    Partners LLC, an affiliate of Menlo Equities. Mathilda Research Centre is
    comprised of two buildings, 1194 and 1184 Mathilda Avenue. Both buildings
    are leased to Juniper Networks on a NNN basis.

    The following table sets forth Lease Expirations (in square feet) for the
portfolio of properties we owned or had an interest in (excluding properties
controlled by BCSP) as of June 30, 2001.

<Table>
<Caption>
                                             SQUARE     % OF SQUARE    ANNUAL    % ANNUAL      # OF
                                             FEET(1)      FEET(2)     RENT(3)    RENT(4)    TENANTS(5)
                                            ---------   -----------   --------   --------   ----------
                                                              (DOLLARS IN THOUSANDS)
<S>                                         <C>         <C>           <C>        <C>        <C>
July 1, 2001 - December 31, 2001..........     14,994        1.8%     $   131       0.5%          4
2002......................................     27,063        3.3%         333       1.3%          6
2003......................................     66,558        8.0%         435       1.8%          7
2004......................................     13,141        1.6%         177       0.7%          3
2005......................................    121,228       14.6%       3,906      15.7%          5
Thereafter................................    475,903       57.5%      19,899      80.0%          9
                                            ---------       ----      -------     -----         ---
  Total...................................    718,887       86.8%     $24,881     100.0%         34
                                            =========       ====      =======     =====         ===
</Table>

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

(1) Total area in square feet covered by such leases.

(2) Percentage of total square feet of our portfolio.

(3) Annualized expiring base rental income represented by such leases in the
    year of expiration plus the current tenant payments on account of operating
    expense and real estate tax escalation charges.

(4) Calculated as annual rent divided by the total annual rent.

(5) The number of tenants whose leases will expire.

ITEM 3. QUANTITATIVE AND QUALITATIVE DISCLOSURES ABOUT MARKET RISK.

    We are exposed to certain financial market risks, the most predominant being
fluctuations in the prime, Eurodollar and LIBOR interest rates. Interest rate
fluctuations are monitored by management as an integral part of our overall risk
management program, which recognizes the unpredictability of financial markets
and seeks to reduce the potentially adverse effect on our results of operations.
The effect of interest rate fluctuations historically has been small relative to
other factors affecting operating results, such as rental rates and occupancy.

    The following table summarizes our debt obligations outstanding as of
June 30, 2001. This information should be read in conjunction with Notes 5 and 6
to the condensed consolidated financial statements and with the information
contained under Capitalization in Part I--Item 2.

<Table>
<Caption>
                                                          EXPECTED MATURITY DATE
                         7/1/01-
                         12/31/01     2002       2003       2004       2005     THEREAFTER    TOTAL     FAIR VALUE
                         --------   --------   --------   --------   --------   ----------   --------   ----------
                                                          (DOLLARS IN THOUSANDS)
<S>                      <C>        <C>        <C>        <C>        <C>        <C>          <C>        <C>
Liabilities
DEBT:
-----------------------
FIXED RATE.............   $   23     $   42    $    46     $   51     $   55      $1,157     $ 1,374      $ 1,600
Weighted Average Fixed
  Interest Rate........     9.0%       9.0%       9.0%       9.0%       9.0%        9.0%        9.0%

VARIABLE RATE..........       --         --    $23,966         --         --          --     $23,966      $23,966
Current Variable
  Interest Rate........       --         --      6.16%         --         --          --       6.16%
</Table>

                                       16
<Page>
                         BEACON CAPITAL PARTNERS, INC.

PART II--OTHER INFORMATION

Item 1.  Legal Proceedings

    None.

Item 2.  Changes in Securities and Use of Proceeds

    None.

Item 3.  Defaults upon Senior Securities

    None.

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

    (a) On April 4, 2001, the Company's stockholders voted in favor of a
proposal to adopt an asset sale plan for the Company. The vote was 15,219,828 in
favor and 2,129,083 against. The stockholders voted against a proposal to amend
the Company's charter. The vote was 12,711,835 in favor and 4,637,076 against;
however, in order to pass, this proposal required a favorable vote from
shareholders holding at least two-thirds of all outstanding shares.

    (b) BCP's 2001 Annual Meeting of Shareholders (the "Annual Meeting") was
held on June 24, 2001.

    (c) At the Annual Meeting, the following individuals were elected to BCP's
Board of Directors as Class III Directors:

<Table>
<Caption>
                                                     VOTES FOR    VOTES WITHHELD
                                                     ----------   --------------
<S>                                                  <C>          <C>
Steven Shulman.....................................  15,047,220              0
Scott M. Sperling..................................  15,047,220              0
</Table>

    The following individuals are directors whose term of office as a director
continued after the Annual Meeting:

       Alan M. Leventhal (Class I)
       Robert M. Melzer (Class I)
       Lionel P. Fortin (Class II)
       Stephen T. Clark (Class II)

    (d) The following additional proposal was considered at the Annual Meeting:

<Table>
<Caption>
                                          VOTES FOR    VOTES AGAINST   VOTES ABSTAIN
                                          ----------   -------------   -------------
<S>                                       <C>          <C>             <C>
Ratification of the appointment of Ernst
  & Young LLP, as BCP's independent
  accountants for the fiscal year ending
  December 31, 2001.....................  15,012,220        35,000               0
</Table>

Item 5.  Other Information

    None.

Item 6.  Exhibits and Reports on Form 8-K

<Table>
        <S>  <C>     <C>
        (a)   3.1    Articles of Incorporation.(1)
              3.2    Certificate of Correction to Articles of Incorporation.(1)
              3.3    Amended and Restated By-laws.(1)
              3.4    Amended and Restated Agreement of Limited Partnership of
                       Beacon Capital Partners, L.P.(2)
</Table>

<Table>
        <S>  <C>
        (b)  8-K filed April 15, 2001 announcing the adoption of the
             Asset Sale Plan.
             8-K filed June 28, 2001 announcing the sale of properties in
             the Dallas Office and Industrial Portfolio.
</Table>

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

(1) Previously filed as an exhibit to BCP's Registration Statement on Form S-11
    (SEC File No. 333-56937) filed with the Commission on June 16, 1998.

(2) Previously filed as an exhibit to BCP's Annual Report on Form 10-K for the
    year ended December 31, 2000.

                                       17
<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.

<Table>
<S>                                                   <C>
                                                      BEACON CAPITAL PARTNERS, INC.

                                                      /s/ RANDY J. PARKER
                                                      ------------------------------------------------
                                                      Randy J. Parker
                                                      Chief Financial Officer (Authorized Officer and
August 13, 2001                                       Principal Accounting Officer)
</Table>

                                       18
<Page>
                                 EXHIBIT INDEX

<Table>
<Caption>
     EXHIBIT NO.        DESCRIPTION
---------------------   -----------
<S>                     <C>                                                           <C>
Exhibit 3.1             Articles of Incorporation (1)

Exhibit 3.2             Certificate of Correction to Articles of Incorporation (1)

Exhibit 3.3             Amended and Restated By-laws (1)

Exhibit 3.4             Amended and Restated Agreement of Limited Partnership of
                        Beacon Capital Partners, L.P. (2)
</Table>

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

(1) Previously filed as an exhibit to BCP's Registration Statement on Form S-11
    (SEC File No. 333-56937) filed with the Commission on June 16, 1998.

(2) Previously filed as an exhibit to BCP's Annual Report on Form 10-K for the
    year ended December 31, 2000.

                                       19