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

    <schemaVersion>X0306</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2015-10-30</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0001492691</issuerCik>
        <issuerName>SWIFT TRANSPORTATION Co</issuerName>
        <issuerTradingSymbol>SWFT</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0000901736</rptOwnerCik>
            <rptOwnerName>MOYES JERRY</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>SWIFT TRANSPORTATION COMPANY</rptOwnerStreet1>
            <rptOwnerStreet2>2200 SOUTH 75TH AVENUE</rptOwnerStreet2>
            <rptOwnerCity>PHOENIX</rptOwnerCity>
            <rptOwnerState>AZ</rptOwnerState>
            <rptOwnerZipCode>85043</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>1</isOther>
            <officerTitle>CEO</officerTitle>
            <otherText>Member of 10% group</otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001272829</rptOwnerCik>
            <rptOwnerName>MOYES VICKIE</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>P.O. BOX 1397</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>TOLLESON</rptOwnerCity>
            <rptOwnerState>AZ</rptOwnerState>
            <rptOwnerZipCode>85353</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle></officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001092565</rptOwnerCik>
            <rptOwnerName>MOYES JERRY &amp; VICKIE FAMILY TRUST</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O SWIFT AVIATION GROUP, INC.</rptOwnerStreet1>
            <rptOwnerStreet2>2710 E. OLD TOWER ROAD</rptOwnerStreet2>
            <rptOwnerCity>PHOENIX</rptOwnerCity>
            <rptOwnerState>AZ</rptOwnerState>
            <rptOwnerZipCode>85034</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle></officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Class B Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2015-10-22</value>
            </transactionDate>
            <deemedExecutionDate></deemedExecutionDate>
            <transactionCoding>
                <transactionFormType>5</transactionFormType>
                <transactionCode>G</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>3300000</value>
                    <footnoteId id="F1"/>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>14658799</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                    <footnoteId id="F2"/>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>Manager</value>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Class B Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2015-10-22</value>
            </transactionDate>
            <deemedExecutionDate></deemedExecutionDate>
            <transactionCoding>
                <transactionFormType>5</transactionFormType>
                <transactionCode>G</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>3300000</value>
                    <footnoteId id="F1"/>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>3300000</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                    <footnoteId id="F3"/>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>Manager and Member</value>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
        <nonDerivativeHolding>
            <securityTitle>
                <value>Class B Common Stock</value>
            </securityTitle>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>6820090</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                    <footnoteId id="F4"/>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>Manager and Member</value>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeHolding>
        <nonDerivativeHolding>
            <securityTitle>
                <value>Class A Common Stock</value>
            </securityTitle>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>2590077</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                    <footnoteId id="F4"/>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>Manager and Member</value>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeHolding>
        <nonDerivativeHolding>
            <securityTitle>
                <value>Class A Common Stock</value>
            </securityTitle>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>100</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeHolding>
        <nonDerivativeHolding>
            <securityTitle>
                <value>Class B Common Stock</value>
            </securityTitle>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>26213049</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                    <footnoteId id="F5"/>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>Manager and Member</value>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeHolding>
    </nonDerivativeTable>

    <derivativeTable>
        <derivativeTransaction>
            <securityTitle>
                <value>Forward Sale Contract (obligation to sell)</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <footnoteId id="F6"/>
                <footnoteId id="F7"/>
                <footnoteId id="F8"/>
                <footnoteId id="F9"/>
                <footnoteId id="F10"/>
            </conversionOrExercisePrice>
            <transactionDate>
                <value>2015-10-30</value>
            </transactionDate>
            <deemedExecutionDate></deemedExecutionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>J</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
                <footnoteId id="F6"/>
                <footnoteId id="F7"/>
                <footnoteId id="F8"/>
                <footnoteId id="F9"/>
                <footnoteId id="F10"/>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>1</value>
                </transactionShares>
                <transactionPricePerShare>
                    <footnoteId id="F6"/>
                    <footnoteId id="F7"/>
                    <footnoteId id="F8"/>
                    <footnoteId id="F9"/>
                    <footnoteId id="F10"/>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <exerciseDate>
                <footnoteId id="F6"/>
                <footnoteId id="F7"/>
                <footnoteId id="F8"/>
                <footnoteId id="F9"/>
                <footnoteId id="F10"/>
            </exerciseDate>
            <expirationDate>
                <footnoteId id="F6"/>
                <footnoteId id="F7"/>
                <footnoteId id="F8"/>
                <footnoteId id="F9"/>
                <footnoteId id="F10"/>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Class A Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>3300000</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>1</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                    <footnoteId id="F3"/>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>Manager and Member</value>
                </natureOfOwnership>
            </ownershipNature>
        </derivativeTransaction>
        <derivativeTransaction>
            <securityTitle>
                <value>Forward Sale Contract (obligation to sell)</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <footnoteId id="F11"/>
                <footnoteId id="F13"/>
                <footnoteId id="F14"/>
                <footnoteId id="F15"/>
                <footnoteId id="F16"/>
                <footnoteId id="F12"/>
            </conversionOrExercisePrice>
            <transactionDate>
                <value>2015-10-30</value>
            </transactionDate>
            <deemedExecutionDate></deemedExecutionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>J</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
                <footnoteId id="F11"/>
                <footnoteId id="F13"/>
                <footnoteId id="F14"/>
                <footnoteId id="F15"/>
                <footnoteId id="F16"/>
                <footnoteId id="F12"/>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>1</value>
                </transactionShares>
                <transactionPricePerShare>
                    <footnoteId id="F11"/>
                    <footnoteId id="F13"/>
                    <footnoteId id="F14"/>
                    <footnoteId id="F15"/>
                    <footnoteId id="F16"/>
                    <footnoteId id="F12"/>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <exerciseDate>
                <footnoteId id="F11"/>
                <footnoteId id="F13"/>
                <footnoteId id="F14"/>
                <footnoteId id="F15"/>
                <footnoteId id="F16"/>
                <footnoteId id="F12"/>
            </exerciseDate>
            <expirationDate>
                <footnoteId id="F11"/>
                <footnoteId id="F13"/>
                <footnoteId id="F14"/>
                <footnoteId id="F15"/>
                <footnoteId id="F16"/>
                <footnoteId id="F12"/>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Class A Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>25994016</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>0</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                    <footnoteId id="F5"/>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>Manager and Member</value>
                </natureOfOwnership>
            </ownershipNature>
        </derivativeTransaction>
        <derivativeTransaction>
            <securityTitle>
                <value>Forward Sale Contract (obligation to sell)</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <footnoteId id="F11"/>
                <footnoteId id="F13"/>
                <footnoteId id="F14"/>
                <footnoteId id="F15"/>
                <footnoteId id="F16"/>
                <footnoteId id="F12"/>
            </conversionOrExercisePrice>
            <transactionDate>
                <value>2015-10-30</value>
            </transactionDate>
            <deemedExecutionDate></deemedExecutionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>J</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
                <footnoteId id="F11"/>
                <footnoteId id="F13"/>
                <footnoteId id="F14"/>
                <footnoteId id="F15"/>
                <footnoteId id="F16"/>
                <footnoteId id="F12"/>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>1</value>
                </transactionShares>
                <transactionPricePerShare>
                    <footnoteId id="F11"/>
                    <footnoteId id="F13"/>
                    <footnoteId id="F14"/>
                    <footnoteId id="F15"/>
                    <footnoteId id="F16"/>
                    <footnoteId id="F12"/>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <exerciseDate>
                <footnoteId id="F11"/>
                <footnoteId id="F13"/>
                <footnoteId id="F14"/>
                <footnoteId id="F15"/>
                <footnoteId id="F16"/>
                <footnoteId id="F12"/>
            </exerciseDate>
            <expirationDate>
                <footnoteId id="F11"/>
                <footnoteId id="F13"/>
                <footnoteId id="F14"/>
                <footnoteId id="F15"/>
                <footnoteId id="F16"/>
                <footnoteId id="F12"/>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Class A Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>13700000</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>1</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                    <footnoteId id="F5"/>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>Manager and Member</value>
                </natureOfOwnership>
            </ownershipNature>
        </derivativeTransaction>
        <derivativeTransaction>
            <securityTitle>
                <value>Forward Sale Contract (obligation to sell)</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <footnoteId id="F11"/>
                <footnoteId id="F13"/>
                <footnoteId id="F14"/>
                <footnoteId id="F15"/>
                <footnoteId id="F16"/>
                <footnoteId id="F12"/>
            </conversionOrExercisePrice>
            <transactionDate>
                <value>2015-10-30</value>
            </transactionDate>
            <deemedExecutionDate></deemedExecutionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>J</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
                <footnoteId id="F11"/>
                <footnoteId id="F13"/>
                <footnoteId id="F14"/>
                <footnoteId id="F15"/>
                <footnoteId id="F16"/>
                <footnoteId id="F12"/>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>1</value>
                </transactionShares>
                <transactionPricePerShare>
                    <footnoteId id="F11"/>
                    <footnoteId id="F13"/>
                    <footnoteId id="F14"/>
                    <footnoteId id="F15"/>
                    <footnoteId id="F16"/>
                    <footnoteId id="F12"/>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <exerciseDate>
                <footnoteId id="F11"/>
                <footnoteId id="F13"/>
                <footnoteId id="F14"/>
                <footnoteId id="F15"/>
                <footnoteId id="F16"/>
                <footnoteId id="F12"/>
            </exerciseDate>
            <expirationDate>
                <footnoteId id="F11"/>
                <footnoteId id="F13"/>
                <footnoteId id="F14"/>
                <footnoteId id="F15"/>
                <footnoteId id="F16"/>
                <footnoteId id="F12"/>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Class A Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>12294016</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>1</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                    <footnoteId id="F5"/>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>Manager and Member</value>
                </natureOfOwnership>
            </ownershipNature>
        </derivativeTransaction>
    </derivativeTable>

    <footnotes>
        <footnote id="F1">The reported securities were transferred from M Capital Group Investors, LLC (&quot;M Capital I&quot;) to Cactus Holding Company, LLC (&quot;Cactus I&quot;).</footnote>
        <footnote id="F2">Shares are owned by M Capital I, and indirectly by the Jerry and Vickie Moyes Family Trust (the &quot;JVMF Trust&quot;), as the sole manager of M Capital I.  The reporting persons disclaim any beneficial ownership of these securities except to the extent of their pecuniary interest therein, and the inclusion of these securities in this report shall not be deemed an admission of beneficial ownership of these securities for Section 16 or for any other purpose.</footnote>
        <footnote id="F3">Shares are owned by Cactus I, an entity controlled by the JVMF Trust, for which Mr. and Mrs. Moyes serve as co-trustees.  The JVMF Trust, Mr. Moyes, and Mrs. Moyes are all of the members of Cactus I.</footnote>
        <footnote id="F4">Shares are owned by Cactus Holding Company II, LLC (&quot;Cactus II&quot;), an entity controlled by the JVMF Trust, for which Mr. and Mrs. Moyes serve as co-trustees.  The JVMF Trust, Mr. Moyes, and Mrs. Moyes are all of the members of Cactus II.</footnote>
        <footnote id="F5">Shares are owned by M Capital Group Investors II, LLC (&quot;M Capital II&quot;), and indirectly by the JVMF Trust, as the sole manager of M Capital II.  Mr. Moyes, Mrs. Moyes, and the JVMF Trust constitute certain of the members of M Capital II.  The reporting persons disclaim any beneficial ownership of these securities except to the extent of their pecuniary interest therein, and the inclusion of these securities in this report shall not be deemed an admission of beneficial ownership of these securities for Section 16 or for any other purpose.</footnote>
        <footnote id="F6">On October 30, 2015, Cactus I entered into a Master Terms and Conditions for Prepaid Variable Share Forward Transactions, together with a supplemental confirmation thereto (the &quot;Cactus Forward Agreement&quot;) with Citigroup Global Markets Inc. (&quot;CGMI&quot;). Under the Cactus Forward Agreement, Cactus I is obligated to deliver a variable amount of Class A Common Stock, par value $0.01 per share, of Swift Transportation Company (&quot;Class A Common Stock&quot;), or an equivalent amount of cash, upon certain dates specified in the Cactus Forward Agreement.  The number of shares deliverable under the Cactus Forward Agreement depends on the &quot;Forward Floor Price,&quot; &quot;Forward Cap Price,&quot; &quot;Number of Shares,&quot; and &quot;Settlement Price,&quot; each as defined in the Cactus Forward Agreement.  The Cactus Forward Agreement has three components, each with its own &quot;Valuation Date&quot; and &quot;Number of Shares.&quot;</footnote>
        <footnote id="F7">Under the Cactus Forward Agreement, the Forward Floor Price is defined as $22.00, the Forward Cap Price is defined as $26.40, and the Number of Shares for each component is 1,100,000. The Settlement Price under the Cactus Forward Agreement is defined as the volume-weighted average price per share of Class A Common Stock on the New York Stock Exchange on the relevant &quot;Valuation Date&quot; (as defined in each component). The Valuation Dates range from November 21, 2016 to November 23, 2016.  The shares or cash deliverable by Cactus I must be delivered on the date that is one Settlement Cycle (as defined in the Cactus Forward Agreement) following the relevant Valuation Date.</footnote>
        <footnote id="F8">The maximum number of shares to be delivered under the Cactus Forward Agreement is 3,300,000 shares of Class A Common Stock, but the actual number of shares required to be delivered under each component depends on the Settlement Price with respect to such component.</footnote>
        <footnote id="F9">Under the Cactus Forward Agreement, if the Settlement Price is less than or equal to the Forward Floor Price on the relevant Valuation Date, the Number of Shares attributable to that component must be delivered. If the Settlement Price is greater than the Forward Floor Price but less than or equal to the Forward Cap Price, the number of shares to be delivered equals the Forward Floor Price, divided by the Settlement Price, multiplied by the Number of Shares.  If the Settlement Price is greater than the Forward Cap Price, the number of shares to be delivered is the equal to the product of (i) the Number of Shares and (ii) a fraction (a) the numerator of which is the sum of (x) the Forward Floor Price and (y) the Settlement Price minus the Forward Cap Price, and (b) the denominator of which is the Settlement Price.</footnote>
        <footnote id="F10">Cactus I received a cash payment of $48,300,000 from CGMI in connection with the Cactus Forward Agreement.</footnote>
        <footnote id="F11">On October 29, 2013, M Capital II entered into a Master Terms and Conditions for Prepaid Variable Share Forward Transactions (together with the supplemental confirmations thereto, the &quot;M Capital Forward Agreement&quot;) with Citibank, N.A. (&quot;Citibank&quot;). Under the M Capital Forward Agreement, M Capital II is obligated to deliver a variable amount of Class A Common Stock, or an equivalent amount of cash, upon certain dates specified in the M Capital Forward Agreement. On February 18, 2015, M Capital II and Citibank amended the terms of the M Capital Forward Agreement by entering into amended and restated supplemental confirmations with respect thereto.</footnote>
        <footnote id="F12">On October 30, 2015, M Capital II and Citibank entered into a Second Amended and Restated Transaction 1 Supplemental Confirmation (the &quot;Amendment&quot;), which amends the terms of the first tranche of the M Capital Forward Agreement.  This Form 4 reports the Amendment.  The terms of the second tranche of the M Capital Forward Agreement were not changed as part of the Amendment.</footnote>
        <footnote id="F13">The Amendment made the following changes, among other technical changes, to the existing tranche 1 of the M Capital Forward Agreement: (1) decreased the Forward Floor Price from $22.54 to $22.00; (2) decreased the Forward Cap Price from $34.00 to $26.40; and (3) extended the Valuation Dates from November 4 through November 6, 2015, to November 21 through November 23, 2016.  The maximum number of shares to be delivered under tranche 1 of the M Capital Forward Agreement remained the same at 13,700,000.</footnote>
        <footnote id="F14">As was the case prior to the Amendment, the shares or cash deliverable by M Capital II must be delivered on the date that is one Settlement Cycle (as defined in the M Capital Forward Agreement) following the relevant Valuation Date. In connection with the Amendment, M Capital II made a cash payment to Citibank of $18,500,000.</footnote>
        <footnote id="F15">Tranche 2 of the M Capital Forward Agreement remains unchanged, with a Forward Floor Price of $23.30, a Forward Cap Price of $36.50, Valuation Dates ranging from July 5, 2016 through August 1, 2016, and the maximum number of shares to be delivered at 12,294,016.</footnote>
        <footnote id="F16">The formulas used to determine the number of shares to be delivered under the M Capital Forward Agreement remained unchanged, and are the same as those described for the Cactus Forward Agreement in Footnote 9 above.</footnote>
    </footnotes>

    <remarks></remarks>

    <ownerSignature>
        <signatureName>/s/ Jerry Moyes, by Earl Scudder, attorney-in-fact, pursuant to a POA previously filed</signatureName>
        <signatureDate>2015-11-03</signatureDate>
    </ownerSignature>

    <ownerSignature>
        <signatureName>/s/ Vickie Moyes, by Earl Scudder, attorney-in-fact, pursuant to a POA previously filed</signatureName>
        <signatureDate>2015-11-03</signatureDate>
    </ownerSignature>

    <ownerSignature>
        <signatureName>/s/ Jerry Moyes, Co-Trustee of the Jerry and Vickie Moyes Family Trust, by Earl Scudder, attorney-in-fact, pursuant to a POA previously filed</signatureName>
        <signatureDate>2015-11-03</signatureDate>
    </ownerSignature>

    <ownerSignature>
        <signatureName>/s/ Vickie Moyes, Co-Trustee of the Jerry and Vickie Moyes Family Trust, by Earl Scudder, attorney-in-fact, pursuant to a POA previously filed</signatureName>
        <signatureDate>2015-11-03</signatureDate>
    </ownerSignature>
</ownershipDocument>
