<Page>
FORM N-CSR
CERTIFIED SHAREHOLDER REPORT OF REGISTERED
MANAGEMENT INVESTMENT COMPANIES
Investment Company Act File Number: 811-10597
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Tax-Managed Mid-Cap Core Portfolio
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(Exact Name of Registrant as Specified in Charter)
The Eaton Vance Building, 255 State Street, Boston, Massachusetts 02109
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(Address of Principal Executive Offices)
Alan R. Dynner
The Eaton Vance Building, 255 State Street, Boston, Massachusetts 02109
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(Name and Address of Agent for Services)
(617) 482-8260
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(Registrant's Telephone Number)
October 31
Date of Fiscal Year End
October 31, 2003
Date of Reporting Period
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ITEM 1. REPORTS TO STOCKHOLDERS
<Page>
TAX-MANAGED MID-CAP CORE PORTFOLIO AS OF OCTOBER 31, 2003
PORTFOLIO OF INVESTMENTS
COMMON STOCKS -- 97.3%
<Table>
<Caption>
SECURITY SHARES VALUE
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ADVERTISING AGENCIES -- 2.1%
Omnicom Group, Inc. 12,300 $ 981,540
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$ 981,540
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AIRLINES -- 1.3%
SkyWest, Inc. 31,900 $ 589,831
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$ 589,831
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BANKS - REGIONAL -- 3.1%
City National Corp. 9,500 $ 571,995
SouthTrust Corp. 15,200 484,120
Synovus Financial Corp. 13,800 380,880
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$ 1,436,995
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BROADCASTING AND RADIO -- 2.0%
Cox Radio, Inc. Class A(1) 42,100 $ 931,252
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$ 931,252
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BUILDING PRODUCTS -- 1.1%
Valspar Corp. 11,000 $ 524,700
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$ 524,700
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BUSINESS SERVICES - MISCELLANEOUS -- 5.8%
ChoicePoint, Inc.(1) 23,366 $ 818,745
Fair Isaac Corp. 7,200 459,216
Fiserv, Inc.(1) 13,400 473,288
SEI Investments Co. 14,700 428,064
The Reynolds and Reynolds Co., Class A 18,700 507,892
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$ 2,687,205
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CHEMICALS -- 1.8%
Air Products and Chemicals, Inc. 18,700 $ 849,167
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$ 849,167
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COMPUTER SERVICES -- 1.7%
SunGard Data Systems, Inc.(1) 27,200 $ 762,960
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$ 762,960
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COMPUTER SOFTWARE -- 1.2%
National Instruments Corp. 12,500 $ 532,250
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$ 532,250
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COMPUTERS - INTEGRATED SYSTEMS -- 3.8%
Adobe Systems, Inc. 8,800 $ 385,792
Affiliated Computer Services, Inc.(1) 18,100 885,633
Jack Henry & Associates, Inc. Class A 25,000 499,500
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$ 1,770,925
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COSMETICS & TOILETRIES -- 1.8%
Alberto-Culver Co. Class A 13,100 $ 830,409
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$ 830,409
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DISTRIBUTION / WHOLESALE -- 1.7%
CDW Corp. 13,100 $ 786,655
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$ 786,655
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EDUCATION -- 1.4%
Education Management Corp.(1) 10,500 $ 663,390
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$ 663,390
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ELECTRICAL EQUIPMENT -- 1.7%
Cooper Industries Ltd. Class A 14,400 $ 761,760
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$ 761,760
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ELECTRONICS - EQUIPMENT / INSTRUMENTS -- 1.6%
Amphenol Corp. Class A(1) 12,700 $ 746,125
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$ 746,125
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ELECTRONICS - SEMICONDUCTORS -- 1.5%
QLogic Corp.(1) 12,600 $ 706,230
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$ 706,230
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ENGINEERING AND CONSTRUCTION -- 1.8%
Jacobs Engineering Group, Inc.(1) 17,900 $ 829,128
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$ 829,128
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</Table>
See notes to financial statements.
16
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<Table>
<Caption>
SECURITY SHARES VALUE
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FINANCE - INVESTMENT MANAGEMENT -- 7%
Affiliated Managers Group, Inc.(1) 13,000 $ 942,500
Ambac Financial Group, Inc. 7,700 544,698
Franklin Resources, Inc. 17,700 839,334
Legg Mason, Inc. 11,100 924,075
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$ 3,250,607
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FOOD - WHOLESALE / DISTRIBUTION -- 1.5%
Performance Food Group Co.(1) 19,000 $ 707,750
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$ 707,750
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GAS DISTRIBUTION -- 1.1%
Piedmont Natural Gas Co., Inc. 12,100 $ 480,733
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$ 480,733
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HEALTHCARE SERVICES -- 2.5%
First Health Group Corp.(1) 17,100 $ 417,411
WellPoint Health Networks, Inc.(1) 8,000 711,200
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$ 1,128,611
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HOUSEHOLD PRODUCTS -- 1.9%
Mohawk Industries, Inc.(1) 11,700 $ 867,204
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$ 867,204
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INSURANCE -- 2.2%
Ace Ltd. 28,300 $ 1,018,800
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$ 1,018,800
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INSURANCE BROKERS -- 1.8%
Arthur J. Gallagher & Co., Inc. 28,500 $ 831,915
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$ 831,915
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INVESTMENT SERVICES -- 2.1%
A.G. Edwards, Inc. 24,200 $ 980,100
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$ 980,100
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MANUFACTURING -- 4.1%
Danaher Corp. 5,900 $ 488,815
Dover Corp. 19,500 760,890
Nucor Corp. 11,700 641,511
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$ 1,891,216
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MEDICAL - HOSPITALS -- 1.8%
Health Management Associates, Inc. Class A 37,100 $ 821,765
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$ 821,765
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MEDICAL DEVICES -- 1.5%
Varian Medical Systems, Inc.(1) 10,700 $ 684,158
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$ 684,158
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MEDICAL PRODUCTS -- 5.3%
Biomet, Inc. 18,400 $ 659,824
C.R. Bard, Inc. 8,700 696,435
Patterson Dental Co.(1) 9,200 588,616
Renal Care Group, Inc.(1) 13,200 495,132
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$ 2,440,007
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MEDICAL SERVICES / SUPPLIES -- 1.8%
DENTSPLY International, Inc. 19,100 $ 844,029
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$ 844,029
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MULTI-UTILITIES -- 1.8%
Questar Corp. 26,700 $ 847,725
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$ 847,725
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OFFICE ELECTRONICS / TECHNOLOGY -- 1.8%
Zebra Technologies Corp. Class A(1) 14,250 $ 811,537
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$ 811,537
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OIL AND GAS - EXPLORATION AND PRODUCTION -- 5.8%
Apache Corp. 9,425 $ 657,111
EOG Resources, Inc. 13,600 573,104
Newfield Exploration Co.(1) 21,900 870,087
Pogo Producing Co. 13,300 556,073
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$ 2,656,375
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PERSONAL PRODUCTS -- 1.1%
Estee Lauder Companies Inc., (The) Class A 14,000 $ 523,460
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$ 523,460
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PRINTING AND BUSINESS PRODUCTS -- 1.5%
Avery Dennison Corp. 13,200 $ 694,056
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$ 694,056
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</Table>
See notes to financial statements.
17
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<Table>
<Caption>
SECURITY SHARES VALUE
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PUBLISHING -- 1.6%
E.W. Scripps Co. 8,000 $ 743,280
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$ 743,280
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RETAIL - DISCOUNT -- 1.1%
Family Dollar Stores, Inc. 11,300 $ 492,793
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$ 492,793
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RETAIL - RESTAURANTS -- 3.8%
Brinker International, Inc.(1) 30,000 $ 954,900
Sonic Corp.(1) 28,400 789,804
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$ 1,744,704
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RETAIL - SPECIALTY AND APPAREL -- 2.4%
Bed Bath and Beyond, Inc.(1) 11,100 $ 468,864
Tiffany & Co. 13,000 616,850
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$ 1,085,714
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SEMICONDUCTORS &
SEMICONDUCTOR EQUIPMENT -- 2.2%
Microchip Technology, Inc. 30,650 $ 1,002,562
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$ 1,002,562
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TELECOMMUNICATIONS -- 1.3%
CenturyTel, Inc. 16,700 $ 597,025
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$ 597,025
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TRANSPORTATION -- 2.9%
C.H. Robinson Worldwide, Inc. 16,300 $ 638,634
Expeditors International of Washington, Inc 18,000 675,720
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$ 1,314,354
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TOTAL COMMON STOCKS
(IDENTIFIED COST $37,950,093) $ 44,851,002
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TOTAL INVESTMENTS -- 97.3%
(IDENTIFIED COST $37,950,093) $ 44,851,002
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OTHER ASSETS, LESS LIABILITIES -- 2.7% $ 1,261,269
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NET ASSETS -- 100.0% $ 46,112,271
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</Table>
(1) Non-income producing security.
See notes to financial statements.
18
<Page>
TAX-MANAGED MID-CAP CORE PORTFOLIO AS OF OCTOBER 31, 2003
FINANCIAL STATEMENTS
STATEMENT OF ASSETS AND LIABILITIES
AS OF OCTOBER 31, 2003
<Table>
ASSETS
Investments, at value (identified cost, $37,950,093) $ 44,851,002
Cash 1,128,349
Receivable for investments sold 684,463
Interest and dividends receivable 11,317
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TOTAL ASSETS $ 46,675,131
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LIABILITIES
Payable for investments purchased $ 539,190
Payable to affiliate for Trustees' fees 62
Accrued expenses 23,608
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TOTAL LIABILITIES $ 562,860
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NET ASSETS APPLICABLE TO INVESTORS' INTEREST IN PORTFOLIO $ 46,112,271
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SOURCES OF NET ASSETS
Net proceeds from capital contributions and withdrawals $ 39,211,362
Net unrealized appreciation (computed on the basis of identified cost) 6,900,909
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TOTAL $ 46,112,271
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</Table>
STATEMENT OF OPERATIONS
FOR THE YEAR ENDED
OCTOBER 31, 2003
<Table>
INVESTMENT INCOME
Dividends $ 216,653
Interest 3,060
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TOTAL INVESTMENT INCOME $ 219,713
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EXPENSES
Investment adviser fee $ 229,597
Trustees' fees and expenses 192
Custodian fee 30,994
Legal and accounting services 20,933
Miscellaneous 2,898
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TOTAL EXPENSES $ 284,614
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NET INVESTMENT LOSS $ (64,901)
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REALIZED AND UNREALIZED GAIN (LOSS)
Net realized gain (loss) --
Investment transactions (identified cost basis) $ (927,356)
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NET REALIZED LOSS $ (927,356)
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Change in unrealized appreciation (depreciation) --
Investments (identified cost basis) $ 8,290,032
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NET CHANGE IN UNREALIZED APPRECIATION (DEPRECIATION) $ 8,290,032
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NET REALIZED AND UNREALIZED GAIN $ 7,362,676
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NET INCREASE IN NET ASSETS FROM OPERATIONS $ 7,297,775
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</Table>
See notes to financial statements.
19
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STATEMENTS OF CHANGES IN NET ASSETS
<Table>
<Caption>
INCREASE (DECREASE) YEAR ENDED PERIOD ENDED
IN NET ASSETS OCTOBER 31, 2003 OCTOBER 31, 2002(1)
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From operations --
Net investment loss $ (64,901) $ (49,816)
Net realized loss (927,356) (577,498)
Net change in unrealized
appreciation (depreciation) 8,290,032 (1,389,123)
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NET INCREASE (DECREASE) IN
NET ASSETS FROM OPERATIONS $ 7,297,775 $ (2,016,437)
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Capital transactions --
Contributions $ 25,984,940 $ 19,978,729
Withdrawals (4,319,456) (913,290)
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NET INCREASE IN NET ASSETS FROM
CAPITAL TRANSACTIONS $ 21,665,484 $ 19,065,439
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NET INCREASE IN NET ASSETS $ 28,963,259 $ 17,049,002
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NET ASSETS
At beginning of year $ 17,149,012 $ 100,010
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AT END OF YEAR $ 46,112,271 $ 17,149,012
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</Table>
(1) For the period from the start of business, March 1, 2002, to October 31,
2002.
See notes to financial statements.
20
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SUPPLEMENTARY DATA
<Table>
<Caption>
YEAR ENDED PERIOD ENDED
OCTOBER 31, 2003 OCTOBER 31, 2002(1)
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RATIOS/SUPPLEMENTAL DATA
Ratios (As a percentage of average daily net assets):
Expenses 0.99% 1.68%(2)
Net investment loss (0.22)% (0.81)%(2)
Portfolio Turnover 50% 13%
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TOTAL RETURN 25.97% (14.72)%(3)
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NET ASSETS, END OF YEAR (000'S OMITTED) $ 46,112 $ 17,149
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</Table>
(1) For the period from the start of business, March 1, 2002, to October 31,
2002.
(2) Annualized.
(3) Total return is not computed on an annualized basis.
See notes to financial statements.
21
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TAX-MANAGED MID-CAP CORE PORTFOLIO AS OF OCTOBER 31, 2003
NOTES TO FINANCIAL STATEMENTS
1 SIGNIFICANT ACCOUNTING POLICIES
Tax-Managed Mid-Cap Core Portfolio (the Portfolio) is registered under the
Investment Company Act of 1940, as amended, as a diversified open-end
management investment company. The Portfolio, which was organized as a trust
under the laws of the State of New York on December 10, 2001, seeks to
achieve long-term, after-tax returns by investing in a diversified portfolio
of common stocks of mid-cap companies. The Declaration of Trust permits the
Trustees to issue interests in the Portfolio. At October 31, 2003, Eaton
Vance Tax-Managed Mid-Cap Core Fund held an approximate 32.9% interest in the
Portfolio and one other investor owned an interest greater than 10% that
equaled 66.8%. The following is a summary of significant accounting policies
consistently followed by the Portfolio in the preparation of its financial
statements. The policies are in conformity with accounting principles
generally accepted in the United States of America.
A INVESTMENT VALUATION -- Marketable securities, including options, that are
listed on foreign or U.S. securities exchanges are valued at closing sale
prices on the exchange where such securities are principally traded.
Marketable securities listed in the NASDAQ National Market System are valued
at the NASDAQ official closing price. Unlisted or listed securities for which
closing sale prices are not available are generally valued at the mean
between the latest bid and ask prices. Futures positions on securities or
currencies are generally valued at closing settlement prices. Short-term debt
securities with a remaining maturity of 60 days or less are valued at
amortized cost, which approximates fair value. Other fixed income and debt
securities, including listed securities and securities for which price
quotations are available, will normally be valued on the basis of valuations
furnished by a pricing service. Investments for which valuations or market
quotations are unavailable are valued at fair value using methods determined
in good faith by or at the direction of the Trustees.
B INCOME -- Dividend income is recorded on the ex-dividend date for dividends
received in cash and/or securities. However, if the ex-dividend date has
passed, certain dividends from foreign securities are recorded as the
Portfolio is informed of the ex-dividend date. Interest income is recorded on
the accrual basis.
C INCOME TAXES -- The Portfolio is treated as a partnership for federal tax
purposes. No provision is made by the Portfolio for federal or state taxes on
any taxable income of the Portfolio because each investor in the Portfolio is
ultimately responsible for the payment of any taxes on its share of taxable
income. Since the Portfolio's investors include regulated investment
companies that invest all or substantially all of their assets in the
Portfolio, the Portfolio normally must satisfy the applicable source of
income and diversification requirements (under the Internal Revenue Code) in
order for its investors to satisfy them. The Portfolio will allocate at least
annually among its investors each investor's distributive share of the
Portfolio's net investment income, net realized capital gains, and any other
items of income, gain, loss, deduction or credit.
D FINANCIAL FUTURES CONTRACT -- Upon entering a financial futures contract,
the Portfolio is required to deposit either in cash or securities an amount
(initial margin) equal to a certain percentage of the purchase price
indicated in the financial futures contract. Subsequent payments are made or
received by the Portfolio (margin maintenance) each day, dependent on daily
fluctuations in the value of the underlying security, and are recorded for
book purposes as unrealized gains or losses by the Portfolio. The Portfolio's
investment in financial futures contracts is designed to hedge against
anticipated future changes in price of current or anticipated Portfolio
positions. Should prices move unexpectedly, the Portfolio may not achieve the
anticipated benefits of the financial futures contracts and may realize a
loss.
E PUT OPTIONS -- Upon the purchase of a put option by the Portfolio, the
premium paid is recorded as an investment, the value of which is
marked-to-market daily. When a purchased option expires, the Portfolio will
realize a loss in the amount of the cost of the option. When the Portfolio
enters into a closing sale transaction, the Portfolio will realize a gain or
loss depending on whether the sales proceeds from the closing sale
transaction are greater or less than the cost of the option. When the
Portfolio exercises a put option, settlement is made in cash. The risk
associated with purchasing options is limited to the premium originally paid.
F SECURITIES SOLD SHORT -- The Portfolio may sell a security short if it owns
at least an equal amount of the security sold short or another security
convertible or exchangeable for an equal amount of the security sold short.
Such transactions are done in anticipation of a decline in the market price
of the securities or in order to hedge portfolio positions. The Portfolio
will generally borrow the security sold in order to make delivery to the
buyer. Upon executing the transaction, the Portfolio records the proceeds as
deposits with brokers in the Statement of Assets and Liabilities and
establishes an offsetting payable
22
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for securities sold short for the securities due on settlement. The
proceeds are retained by the broker as collateral for the short position.
The liability is marked-to-market and the Portfolio is required to pay the
lending broker any dividend or interest income earned while the short
position is open. A gain or loss is recorded when the security is delivered
to the broker. The Portfolio may recognize a loss on the transaction if the
market value of the securities sold increases before the securities are
delivered.
G FOREIGN CURRENCY TRANSLATION -- Investment valuations, other assets and
liabilities initially expressed in foreign currencies are converted each
business day into U.S. dollars based upon current exchange rates. Purchases
and sales of foreign investment securities and income and expenses are
converted into U.S. dollars based upon currency exchange rates prevailing on
the respective dates of such transactions. Recognized gains or losses on
investment transactions attributable to foreign currency exchange rates are
recorded for financial statement purposes as net realized gains and losses on
investments. That portion of unrealized gains and losses on investments that
results from fluctuations in foreign currency exchange rates is not
separately disclosed.
H USE OF ESTIMATES -- The preparation of the financial statements in
conformity with accounting principles generally accepted in the United States
of America requires management to make estimates and assumptions that affect
the reported amounts of assets and liabilities at the date of the financial
statements and the reported amounts of income and expense during the
reporting period. Actual results could differ from those estimates.
I OTHER -- Investment transactions are accounted for on a trade date basis.
2 INVESTMENT ADVISER FEE AND OTHER TRANSACTIONS WITH AFFILIATES
The investment adviser fee is earned by Boston Management and Research (BMR),
a wholly-owned subsidiary of Eaton Vance Management (EVM), as compensation
for management and investment advisory services rendered to the Portfolio.
Under the advisory agreement, BMR receives a monthly advisory fee equal to
0.80% annually of the average daily net assets of the Portfolio up to $500
million, and at reduced rates as daily net assets exceed that level. For the
year ended October 31, 2003, the advisory fee amounted to $229,597. Pursuant
to a sub-advisory agreement, BMR has delegated the investment management of
the Portfolio to Atlanta Capital Management Company, LLC (Atlanta Capital), a
majority-owned subsidiary of Eaton Vance. BMR pays Atlanta Capital a monthly
fee for sub-advisory services provided to the Portfolio equal to 0.55%
annually of the average daily net assets up to $500 million, and at reduced
rates as daily net assets exceed that level. Except for Trustees of the
Portfolio who are not members of EVM's or BMR's organization, officers and
Trustees receive remuneration for their services to the Portfolio out of the
investment adviser fee. Trustees of the Portfolio that are not affiliated
with BMR may elect to defer receipt of all or a percentage of their annual
fees in accordance with the terms of the Trustees Deferred Compensation Plan.
For the year ended October 31, 2003, no significant amounts have been
deferred.
Certain officers and Trustees of the Portfolio are officers of the above
organizations.
3 INVESTMENT TRANSACTIONS
Purchases and sales of investments, other than short-term obligations,
aggregated $34,655,917 and $14,180,550, respectively, for the year ended
October 31, 2003.
4 FEDERAL INCOME TAX BASIS OF UNREALIZED APPRECIATION (DEPRECIATION)
The cost and unrealized appreciation (depreciation) in value of the
investments owned at October 31, 2003, as computed on a federal income tax
basis, were as follows:
<Table>
AGGREGATE COST $ 38,204,563
-----------------------------------------------------
Gross unrealized appreciation $ 6,819,922
Gross unrealized depreciation (173,483)
-----------------------------------------------------
NET UNREALIZED APPRECIATION $ 6,646,439
-----------------------------------------------------
</Table>
5 FINANCIAL INSTRUMENTS
The Portfolio may trade in financial instruments with off-balance sheet risk
in the normal course of its investing activities to assist in managing
exposure to various market risks. These financial instruments include written
options, forward foreign currency exchange contracts, and financial futures
contracts and may involve, to a varying degree, elements of risk in excess of
the amounts recognized for financial statement purposes.
The notional or contractual amounts of these instruments represent the
investment the Portfolio has in particular classes of financial instruments
and does not necessarily represent the amounts potentially subject to risk.
The measurement of the risks associated with these instruments is meaningful
only when all related and offsetting
23
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transactions are considered. The Portfolio did not have any open obligations
under these financial instruments at October 31, 2003.
6 LINE OF CREDIT
The Portfolio participates with other portfolios and funds managed by BMR and
EVM and its affiliates in a $150 million unsecured line of credit agreement
with a group of banks. Borrowings will be made by the Portfolio solely to
facilitate the handling of unusual and/or unanticipated short-term cash
requirements. Interest is charged to each participating portfolio or fund
based on its borrowings at an amount above either the Eurodollar rate or
Federal Funds rate. In addition, a fee computed at an annual rate of 0.10% on
the daily unused portion of the line of credit is allocated among the
participating portfolios and funds at the end of each quarter. The Portfolio
did not have any significant borrowings or allocated fees for the year ended
October 31, 2003.
7 INTERESTHOLDER MEETING
The Portfolio held a Special Meeting of Interestholders on June 6, 2003 to
elect Trustees. The results of the vote were as follows:
<Table>
<Caption>
INTEREST IN THE PORTFOLIO
-------------------------
NOMINEE FOR TRUSTEE AFFIRMATIVE WITHHOLD
---------------------------------------------------------
Jessica M. Bibliowicz 99% 1%
Donald R. Dwight 99% 1%
James B. Hawkes 99% 1%
Samuel L. Hayes, III 99% 1%
William H. Park 99% 1%
Norton H. Reamer 99% 1%
Lynn A. Stout 99% 1%
</Table>
Results are rounded to the nearest whole number. Donald R. Dwight retired as
a Trustee effective July 1, 2003 pursuant to the mandatory retirement policy
of the Portfolio.
24
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TAX-MANAGED MID-CAP CORE PORTFOLIO AS OF OCTOBER 31, 2003
INDEPENDENT AUDITORS' REPORT
TO THE TRUSTEES AND INVESTORS OF TAX-MANAGED MID-CAP CORE PORTFOLIO:
We have audited the accompanying statement of assets and liabilities, including
the portfolio of investments, of Tax-Managed Mid-Cap Core Portfolio (the
Portfolio) as of October 31, 2003, and the related statement of operations, and
the statements of changes in net assets and the supplementary data for the year
then ended and the period from the start of business, March 1, 2002, to October
31, 2002. These financial statements and supplementary data are the
responsibility of the Portfolio's management. Our responsibility is to express
an opinion on these financial statements and supplementary data based on our
audits.
We conducted our audits in accordance with auditing standards generally accepted
in the United States of America. Those standards require that we plan and
perform the audit to obtain reasonable assurance about whether the financial
statements and supplementary data are free of material misstatement. An audit
includes examining, on a test basis, evidence supporting the amounts and
disclosures in the financial statements. Our procedures included confirmation of
securities held as of October 31, 2003 by correspondence with the custodian and
brokers; where replies were not received from brokers, we performed other
auditing procedures. An audit also includes assessing the accounting principles
used and significant estimates made by management, as well as evaluating the
overall financial statement presentation. We believe that our audits provide a
reasonable basis for our opinion.
In our opinion, such financial statements and supplementary data present fairly,
in all material respects, the financial position of Tax-Managed Mid-Cap Core
Portfolio at October 31, 2003, the results of its operations for the year then
ended, and the changes in its net assets and the supplementary data for the year
then ended and the period from the start of business, March 1, 2002, to October
31, 2002, in conformity with accounting principles generally accepted in the
United States of America.
DELOITTE & TOUCHE LLP
Boston, Massachusetts
December 16, 2003
25
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EATON VANCE TAX-MANAGED MID-CAP CORE FUND
MANAGEMENT AND ORGANIZATION
FUND MANAGEMENT. The Trustees of Eaton Vance Mutual Funds Trust (the Trust) and
Tax-Managed Mid-Cap Core Portfolio (the Portfolio) are responsible for the
overall management and supervision of the Trust's and Portfolio's affairs. The
Trustees and officers of the Trust and the Portfolio are listed below. Except as
indicated, each individual has held the office shown or other offices in the
same company for the last five years. Trustees and officers of the Trust and the
Portfolio hold indefinite terms of office. The "noninterested Trustees" consist
of those Trustees who are not "interested persons" of the Trust, as that term is
defined under the 1940 Act. The business address of each Trustee and officer is
The Eaton Vance Building, 255 State Street, Boston, Massachusetts 02109. As used
below, "EVC" refers to Eaton Vance Corp., "EV" refers to Eaton Vance, Inc.,
"EVM" refers to Eaton Vance Management, "BMR" refers to Boston Management and
Research, "EVD" refers to Eaton Vance Distributors, Inc. and "Atlanta Capital"
refers to Atlanta Capital Management Company, LLC. EVC and EV are the corporate
parent and trustee, respectively, of EVM and BMR. EVD is the Fund's principal
underwriter, the Portfolio's placement agent and a wholly-owned subsidiary of
EVM.
<Table>
<Caption>
POSITION(S) TERM OF NUMBER OF PORTFOLIOS
WITH THE OFFICE AND IN FUND COMPLEX
NAME AND TRUST AND LENGTH OF PRINCIPAL OCCUPATION(S) OVERSEEN BY OTHER DIRECTORSHIPS
DATE OF BIRTH THE PORTFOLIO SERVICE DURING PAST FIVE YEARS TRUSTEE(1) HELD
- ------------------------------------------------------------------------------------------------------------------------------------
INTERESTED TRUSTEE(S)
Jessica M. Trustee Trustee of Chairman, President and 192 Director of National
Bibliowicz the Trust Chief Executive Officer of Financial Partners
11/28/59 since 1998; National Financial
of the Partners (financial
Portfolio services company) (since
since 2001 April 1999). President and
Chief Operating Officer of
John A. Levin & Co.
(registered investment
adviser) (July 1997 to
April 1999) and a Director
of Baker, Fentress &
Company, which owns John
A. Levin & Co. (July 1997 to
April 1999). Ms.Bibliowicz
is an interested person
because of her affiliation
with a brokerage firm.
James B. Hawkes Trustee of the Trustee of Chairman, President and 194 Director of EVC
11/9/41 Trust; Trustee the Trust Chief Executive Officer of
and President since 1991; BMR, EVC, EVM and EV;
of the Portfolio Trustee and Director of EV; Vice
President of President and Director of
the Portfolio EVD. Trustee and/or
since 2001 officer of 194 registered
investment companies in
the Eaton Vance Fund
Complex. Mr.Hawkes is an
interested person because
of his positions with BMR,
EVM, EVC and EV, which are
affiliates of the Trust
and the Portfolio.
NONINTERESTED TRUSTEE(S)
Samuel L. Hayes, III Trustee Trustee of Jacob H. Schiff Professor 194 Director of Tiffany &
2/23/35 the Trust of Investment Banking Co. (specialty
since 1986; Emeritus, Harvard retailer) and Telect,
of the University Graduate School Inc.
Portfolio of Business Administration. (telecommunication
since 2001 services company)
William H. Park Trustee Since 2003 President and Chief 191 None
9/19/47 Executive Officer, Prizm
Capital Management, LLC
(investment management
firm) (since 2002).
Executive Vice President
and Chief Financial
Officer, United Asset
Management Corporation (a
holding company owning
institutional investment
management firms)
(1982-2001).
Ronald A. Pearlman Trustee Since 2003 Professor of Law, 191 None
7/10/40 Georgetown University Law
Center (since 1999). Tax
Partner, Covington &
Burling, Washington, DC
(1991-2000).
</Table>
26
<Page>
<Table>
<Caption>
POSITION(S) TERM OF NUMBER OF PORTFOLIOS
WITH THE OFFICE AND IN FUND COMPLEX
NAME AND TRUST AND LENGTH OF PRINCIPAL OCCUPATION(S) OVERSEEN BY OTHER DIRECTORSHIPS
DATE OF BIRTH THE PORTFOLIO SERVICE DURING PAST FIVE YEARS TRUSTEE(1) HELD
- ------------------------------------------------------------------------------------------------------------------------------------
NONINTERESTED TRUSTEE(S) (CONTINUED)
Norton H. Reamer Trustee Trustee of President and Chief 194 None
9/21/35 the Trust Executive Officer of Asset
since 1986; Management Finance Corp.
of the (a specialty finance
Portfolio company serving the
since 2001 investment management
industry) (since
October 2003). President,
Unicorn Corporation (an
investment and financial
advisory services company)
(since September 2000).
Formerly, Chairman,
Hellman, Jordan Management
Co., Inc. (an investment
management company)
(2000-2003). Formerly,
Advisory Director of
Berkshire Capital
Corporation (investment
banking firm) (2002-2003).
Formerly, Chairman of the
Board, United Asset
Management Corporation (a
holding company owning
institutional investment
management firms) and
Chairman, President and
Director, UAM Funds
(mutual funds) (1980-2000).
Lynn A. Stout Trustee Trustee of Professor of Law, 194 None
9/14/57 the Trust University of California
since 1998; at Los Angeles School of
of the Law (since July 2001).
Portfolio Formerly, Professor of
since 2001 Law, Georgetown University
Law Center.
</Table>
PRINCIPAL OFFICERS WHO ARE NOT TRUSTEES
<Table>
<Caption>
POSITION(S) TERM OF
WITH THE OFFICE AND
NAME AND TRUST AND LENGTH OF PRINCIPAL OCCUPATION(S)
DATE OF BIRTH THE PORTFOLIO SERVICE DURING PAST FIVE YEARS
- --------------------------------------------------------------------------------------------------------------------
Thomas E. Faust Jr. President of the President of Executive Vice President of EVM, BMR, EVC and EV;
5/31/58 Trust; Vice the Trust Chief Investment Officer of EVM and BMR and
President of the since 2002; Director of EVC. Chief Executive Officer of
Portfolio Vice President Belair Capital Fund LLC, Belcrest Capital Fund
of the LLC, Belmar Capital Fund LLC, Belport Capital
Portfolio Fund LLC and Belrose Capital Fund LLC (private
since 2001 investment companies sponsored by EVM). Officer
of 53 registered investment companies managed by
EVM or BMR.
William H. Ahern, Jr. Vice President of Since 1995 Vice President of EVM and BMR. Officer of 35
7/28/59 the Trust registered investment companies managed by EVM or
BMR.
Thomas J. Fetter Vice President of Since 1997 Vice President of EVM and BMR. Trustee and
8/20/43 the Trust President of The Massachusetts Health & Education
Tax-Exempt Trust. Officer of 127 registered
investment companies managed by EVM or BMR.
William R. Hackney, III Vice President of Since 2001 Managing Partner and member of the Executive
4/12/48 the Portfolio Committee of Atlanta Capital. Officer of 3
registered investment companies managed by EVM or
BMR.
Michael R. Mach Vice President of Since 1999 Vice President of EVM and BMR. Previously,
7/15/47 the Trust Managing Director and Senior Analyst for
Robertson Stephens (1998-1999). Officer of 25
registered investment companies managed by EVM or
BMR.
Robert B. MacIntosh Vice President of Since 1998 Vice President of EVM and BMR. Officer of 127
1/22/57 the Trust registered investment companies managed by EVM or
BMR.
Paul J. Marshall Vice President of Since 2001 Vice President of Atlanta Capital. Portfolio
5/2/65 the Portfolio manager for Bank of America Capital Management
(1995-2000). Officer of 3 registered investment
companies managed by EVM or BMR.
Charles B. Reed Vice President of Since 2001 Vice President of Atlanta Capital. Portfolio
10/9/65 the Portfolio manager with the Florida State Board of
Administration (1995-1998). Officer of 2
registered investment companies managed by EVM or
BMR.
</Table>
27
<Page>
<Table>
<Caption>
POSITION(S) TERM OF
WITH THE OFFICE AND
NAME AND TRUST AND LENGTH OF PRINCIPAL OCCUPATION(S)
DATE OF BIRTH THE PORTFOLIO SERVICE DURING PAST FIVE YEARS
- --------------------------------------------------------------------------------------------------------------------
PRINCIPAL OFFICERS WHO ARE NOT TRUSTEES (CONTINUED)
Duncan W. Richardson Vice President of Since 2001 Senior Vice President and Chief Equity Investment
10/26/57 the Trust Officer of EVM and BMR. Officer of 41 registered
investment companies managed by EVM or BMR.
Walter A. Row, III Vice President of Since 2001 Director of Equity Research and a Vice President of
7/20/57 the Trust EVM and BMR. Officer of 22 registered investment
companies managed by EVM or BMR.
Judith A. Saryan Vice President of Since 2003 Vice President of EVM and BMR. Previously, Portfolio
8/21/54 the Trust Manager and Equity Analyst for State Street Global
Advisers (1980-1999). Officer of 24 registered
investment companies managed by EVM or BMR.
Susan Schiff Vice President of Since 2002 Vice President of EVM and BMR. Officer of 26
3/13/61 the Trust registered investment companies managed by EVM or
BMR.
Alan R. Dynner Secretary Secretary of Vice President, Secretary and Chief Legal Officer of
10/10/40 the Trust BMR, EVM, EVD, EV and EVC. Officer of 194 registered
since 1997; of investment companies managed by EVM or BMR.
the Portfolio
since 2001
Michelle A. Alexander Treasurer of the Since 2002 Vice President of EVM and BMR. Chief Financial
8/25/69 Portfolio Officer of Belair Capital Fund LLC, Belcrest Capital
Fund LLC, Belmar Capital Fund LLC, Belport Capital
Fund LLC and Belrose Capital Fund LLC (private
investment companies sponsored by EVM). Officer of
85 registered investment companies managed by EVM or
BMR.
James L. O'Connor Treasurer of the Since 1989 Vice President of BMR, EVM and EVD. Officer of 115
4/1/45 Trust registered investment companies managed by EVM or
BMR.
</Table>
(1) Includes both master and feeder funds in a master-feeder structure.
The SAI for the Fund includes additional information about the Trustees and
officers of the Fund and the Portfolio and can be obtained without charge by
calling 1-800-225-6265.
28
<Page>
ITEM 2. CODE OF ETHICS
The registrant has adopted a code of ethics applicable to its Principal
Executive Officer, Principal Financial Officer and Principal Accounting Officer.
The registrant undertakes to provide a copy of such code of ethics to any person
upon request, without charge, by calling 1-800-262-1122.
ITEM 3. AUDIT COMMITTEE FINANCIAL EXPERT
The registrant's Board has designated William H. Park, Samuel L. Hayes, III and
Norton H. Reamer, each an independent trustee, as its audit committee financial
experts. Mr. Park is a certified public accountant who is the President and
Chief Executive Officer of Prizm Capital Management, LLC (a fixed income
investment management firm). Previously, he served as Executive Vice President
and Chief Financial Officer of United Asset Management Corporation ("UAM") (a
holding company owning institutional investment management firms). Mr. Hayes is
the Jacob H. Schiff Professor of Investment Banking Emeritus of the Harvard
University Graduate School of Business Administration. Mr. Reamer is the
President of Unicorn Capital (an investment and financial advisory services
company), Chairman of Hellman, Jordan Management Co., Inc. (an investment
management company) and Advisory Director of Berkshire Capital Corporation (an
investment banking firm). Previously, Mr. Reamer was Chairman of the Board of
UAM and Chairman, President and Director of the UAM Funds (mutual funds).
ITEM 4. PRINCIPAL ACCOUNTANT FEES AND SERVICES
Not required in this filing.
ITEM 5. AUDIT COMMITTEE OF LISTED REGISTRANTS
Not required in this filing.
ITEM 6. [RESERVED]
ITEM 7. DISCLOSURE OF PROXY VOTING POLICIES AND PROCEDURES FOR CLOSED-END
MANAGEMENT INVESTMENT COMPANIES
Not required in this filing.
ITEM 8. [RESERVED]
ITEM 9. CONTROLS AND PROCEDURES
(a) It is the conclusion of the registrant's principal executive officer and
principal financial officer that the effectiveness of the registrant's current
disclosure controls and procedures (such disclosure controls and procedures
having been evaluated within 90 days of the date of this filing) provide
reasonable assurance that the information required to be disclosed by the
registrant has been recorded, processed, summarized and reported within the time
period specified in the Commission's rules and forms and that the information
required to be disclosed by the registrant has been accumulated and communicated
to the registrant's principal executive officer and principal financial officer
in order to allow timely decisions regarding required disclosure.
(b) There have been no significant changes in the registrant's internal controls
or in other factors that could significantly affect these controls subsequent to
the date of their evaluation, including any corrective actions with regard to
significant deficiencies and material weaknesses.
ITEM 10. EXHIBITS
(a)(1) Registrant's Code of Ethics - Not applicable (please see Item 2).
(a)(2)(i) Treasurer's Section 302 certification.
(a)(2)(ii) President's Section 302 certification.
(b) Combined Section 906 certification.
<Page>
SIGNATURES
Pursuant to the requirements of the Securities Exchange Act of 1934 and the
Investment Company Act of 1940, the registrant has duly caused this report to be
signed on its behalf by the undersigned, thereunto duly authorized.
TAX-MANAGED MID-CAP CORE PORTFOLIO
By: /S/ James B. Hawkes
-------------------
James B. Hawkes
President
Date: December 16, 2003
-----------------
Pursuant to the requirements of the Securities Exchange Act of 1934 and the
Investment Company Act of 1940, this report has been signed below by the
following persons on behalf of the registrant and in the capacities and on the
dates indicated.
By: /S/ Michelle A. Alexander
-------------------------
Michelle A. Alexander
Treasurer
Date: December 16, 2003
-----------------
By: /S/ James B. Hawkes
-------------------
James B. Hawkes
President
Date: December 16, 2003
-----------------