<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0202</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2006-06-02</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0000101778</issuerCik>
        <issuerName>MARATHON OIL CORP</issuerName>
        <issuerTradingSymbol>MRO</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001239300</rptOwnerCik>
            <rptOwnerName>HOWARD JERRY</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O MARATHON OIL CORPORATION</rptOwnerStreet1>
            <rptOwnerStreet2>5555 SAN FELIPE ROAD</rptOwnerStreet2>
            <rptOwnerCity>HOUSTON</rptOwnerCity>
            <rptOwnerState>TX</rptOwnerState>
            <rptOwnerZipCode>77056</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>Sr. V.P., Corporate Affairs</officerTitle>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>COMMON STOCK</value>
            </securityTitle>
            <transactionDate>
                <value>2006-06-02</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>M</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>6433.000</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>47.65</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>55645.000</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>COMMON STOCK</value>
            </securityTitle>
            <transactionDate>
                <value>2006-06-02</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>M</transactionCode>
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            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>23200.000</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>25.515</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>78845.000</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
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                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>COMMON STOCK</value>
            </securityTitle>
            <transactionDate>
                <value>2006-06-02</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>M</transactionCode>
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            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
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                </transactionShares>
                <transactionPricePerShare>
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                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>92478.000</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
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        <nonDerivativeTransaction>
            <securityTitle>
                <value>COMMON STOCK</value>
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            <transactionDate>
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                <value></value>
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            <transactionAmounts>
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                </transactionPricePerShare>
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            </transactionAmounts>
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            <ownershipNature>
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        <nonDerivativeTransaction>
            <securityTitle>
                <value>COMMON STOCK</value>
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            <transactionDate>
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            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>D</transactionCode>
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            <transactionTimeliness>
                <value></value>
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                <transactionPricePerShare>
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            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
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                </sharesOwnedFollowingTransaction>
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            <ownershipNature>
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        <nonDerivativeTransaction>
            <securityTitle>
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                <transactionCode>S</transactionCode>
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            <transactionTimeliness>
                <value></value>
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            <transactionAmounts>
                <transactionShares>
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                </transactionShares>
                <transactionPricePerShare>
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                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
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                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>82592.000</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
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                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>COMMON STOCK</value>
            </securityTitle>
            <transactionDate>
                <value>2006-06-02</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>S</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
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                </transactionShares>
                <transactionPricePerShare>
                    <value>78.16</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
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                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>78292.000</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
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                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>COMMON STOCK</value>
            </securityTitle>
            <transactionDate>
                <value>2006-06-02</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>S</transactionCode>
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            <transactionTimeliness>
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            <transactionAmounts>
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                <transactionPricePerShare>
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                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
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            <postTransactionAmounts>
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        <nonDerivativeTransaction>
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            <transactionTimeliness>
                <value></value>
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                </transactionShares>
                <transactionPricePerShare>
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                <transactionAcquiredDisposedCode>
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            <postTransactionAmounts>
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            <ownershipNature>
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        <nonDerivativeTransaction>
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            <postTransactionAmounts>
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                    <value>47216.000</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>COMMON STOCK</value>
            </securityTitle>
            <transactionDate>
                <value>2006-06-02</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>S</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>2000.000</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>78.37</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>45216.000</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>COMMON STOCK</value>
            </securityTitle>
            <transactionDate>
                <value>2006-06-02</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>S</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>800.000</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>78.38</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>44416.000</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>COMMON STOCK</value>
            </securityTitle>
            <transactionDate>
                <value>2006-06-02</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>S</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>1200.000</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>78.39</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>43216.000</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <derivativeTable>
        <derivativeTransaction>
            <securityTitle>
                <value>EMPLOYEE STOCK OPTION (Right to Buy)</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>47.65</value>
            </conversionOrExercisePrice>
            <transactionDate>
                <value>2006-06-02</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>M</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>6433.00</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <exerciseDate>
                <value>2006-05-25</value>
                <footnoteId id="F1"/>
            </exerciseDate>
            <expirationDate>
                <value>2015-05-25</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>COMMON STOCK</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>6433.00</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>12867.00</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeTransaction>
        <derivativeTransaction>
            <securityTitle>
                <value>Stock Appreciation Right</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>33.61</value>
            </conversionOrExercisePrice>
            <transactionDate>
                <value>2006-06-02</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>M</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>13633.00</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <exerciseDate>
                <value>2005-05-26</value>
                <footnoteId id="F2"/>
            </exerciseDate>
            <expirationDate>
                <value>2014-05-26</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>COMMON STOCK</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>13633.00</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>27267.00</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeTransaction>
        <derivativeTransaction>
            <securityTitle>
                <value>Employee Stock Option (Right to Buy)</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>25.515</value>
            </conversionOrExercisePrice>
            <transactionDate>
                <value>2006-06-02</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>M</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
                <footnoteId id="F3"/>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>23200.00</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <exerciseDate>
                <value>2004-05-28</value>
                <footnoteId id="F4"/>
            </exerciseDate>
            <expirationDate>
                <value>2013-05-28</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>COMMON STOCK</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>23200.00</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>0.00</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeTransaction>
        <derivativeTransaction>
            <securityTitle>
                <value>Stock Appreciation Right</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>25.515</value>
            </conversionOrExercisePrice>
            <transactionDate>
                <value>2006-06-02</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>M</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
                <footnoteId id="F3"/>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>23200.00</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <exerciseDate>
                <value>2004-05-28</value>
                <footnoteId id="F4"/>
            </exerciseDate>
            <expirationDate>
                <value>2013-05-28</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>COMMON STOCK</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>23200.00</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>0.00</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeTransaction>
    </derivativeTable>

    <footnotes>
        <footnote id="F1">Vests in three cumulative annual installments of 6,433, 6,433, and 6,434 shares on May 25, 2006, 2007, and 2008, respectively.</footnote>
        <footnote id="F2">Vests in three cumulative annual installments of 13,633, 13,633, and 13,634 shares on May 26, 2005, 2006, and 2007, respectively.</footnote>
        <footnote id="F3">Exercise of stock option and cancellation of tandem stock appreciation right.</footnote>
        <footnote id="F4">Vests in three equal annual installments on May 28, 2004, 2005 and 2006.</footnote>
    </footnotes>

    <remarks></remarks>

    <ownerSignature>
        <signatureName>Richard J. Kolencik, Attorney-in-Fact for Jerry Howard</signatureName>
        <signatureDate>2006-06-06</signatureDate>
    </ownerSignature>
</ownershipDocument>
[{"type": "4", "sequence": "1", "filename": "doc4.xml", "description": "PRIMARY DOCUMENT", "secsgml_size_bytes": 45995}]
X0202
4
2006-06-02
0
0000101778
MARATHON OIL CORP
MRO
0001239300
HOWARD JERRY
C/O MARATHON OIL CORPORATION
5555 SAN FELIPE ROAD
HOUSTON
TX
77056
0
1
0
0
Sr. V.P., Corporate Affairs
COMMON STOCK
2006-06-02
4
M
0
6433.000
47.65
A
55645.000
D
COMMON STOCK
2006-06-02
4
M
0
23200.000
25.515
A
78845.000
D
COMMON STOCK
2006-06-02
4
M
0
13633.000
33.61
A
92478.000
D
COMMON STOCK
2006-06-02
4
F
0
2837.000
78.35
D
89641.000
D
COMMON STOCK
2006-06-02
4
D
0
5849.000
78.35
D
83792.000
D
COMMON STOCK
2006-06-02
4
S
0
1200.000
78.13
D
82592.000
D
COMMON STOCK
2006-06-02
4
S
0
4300.000
78.16
D
78292.000
D
COMMON STOCK
2006-06-02
4
S
0
1200.000
78.17
D
77092.000
D
COMMON STOCK
2006-06-02
4
S
0
600.000
78.18
D
76492.000
D
COMMON STOCK
2006-06-02
4
S
0
2600.000
78.19
D
73892.000
D
COMMON STOCK
2006-06-02
4
S
0
4100.000
78.20
D
69792.000
D
COMMON STOCK
2006-06-02
4
S
0
3300.000
78.21
D
66492.000
D
COMMON STOCK
2006-06-02
4
S
0
4700.000
78.22
D
61792.000
D
COMMON STOCK
2006-06-02
4
S
0
3900.000
78.23
D
57892.000
D
COMMON STOCK
2006-06-02
4
S
0
1200.000
78.24
D
56692.000
D
COMMON STOCK
2006-06-02
4
S
0
2900.000
78.25
D
53792.000
D
COMMON STOCK
2006-06-02
4
S
0
1743.000
78.26
D
52049.000
D
COMMON STOCK
2006-06-02
4
S
0
2400.000
78.28
D
49649.000
D
COMMON STOCK
2006-06-02
4
S
0
1433.000
78.34
D
48216.000
D
COMMON STOCK
2006-06-02
4
S
0
600.000
78.35
D
47616.000
D
COMMON STOCK
2006-06-02
4
S
0
400.000
78.36
D
47216.000
D
COMMON STOCK
2006-06-02
4
S
0
2000.000
78.37
D
45216.000
D
COMMON STOCK
2006-06-02
4
S
0
800.000
78.38
D
44416.000
D
COMMON STOCK
2006-06-02
4
S
0
1200.000
78.39
D
43216.000
D
EMPLOYEE STOCK OPTION (Right to Buy)
47.65
2006-06-02
4
M
0
6433.00
0
D
2006-05-25
2015-05-25
COMMON STOCK
6433.00
12867.00
D
Stock Appreciation Right
33.61
2006-06-02
4
M
0
13633.00
0
D
2005-05-26
2014-05-26
COMMON STOCK
13633.00
27267.00
D
Employee Stock Option (Right to Buy)
25.515
2006-06-02
4
M
0
23200.00
0
D
2004-05-28
2013-05-28
COMMON STOCK
23200.00
0.00
D
Stock Appreciation Right
25.515
2006-06-02
4
M
0
23200.00
0
D
2004-05-28
2013-05-28
COMMON STOCK
23200.00
0.00
D
Vests in three cumulative annual installments of 6,433, 6,433, and 6,434 shares on May 25, 2006, 2007, and 2008, respectively.
Vests in three cumulative annual installments of 13,633, 13,633, and 13,634 shares on May 26, 2005, 2006, and 2007, respectively.
Exercise of stock option and cancellation of tandem stock appreciation right.
Vests in three equal annual installments on May 28, 2004, 2005 and 2006.
Richard J. Kolencik, Attorney-in-Fact for Jerry Howard
2006-06-06