Archrock Inc. (AROC): Carlson Capital Increase Its Stake; Plans to Go Activist

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regulations, stock exchange rules and credit policies. In such instances, the positions held in the margin account are pledged as collateral security for the repayment of debit balances in the
account. The margin accounts bear interest at a rate based upon the brokers call rate from time to time in effect. Because other securities are held in the margin accounts, it is not possible to determine the amounts, if any, of margin used to
purchase the Common Shares reported herein.

Item 4. PURPOSE OF TRANSACTION

(a)-(j) The Reporting Persons and their representatives intend, from time
to time, to engage in discussions and correspondence with management and the Issuers Board of Directors (the Board) regarding, among other things, the Issuers business, management and strategic alternatives and
direction. The Reporting Persons believe that the Issuers Common Shares trade at a substantial discount to the Issuers intrinsic value and represent an attractive investment opportunity. The Reporting Persons intend to have
discussions and correspondence with the Issuers management and the Board to discuss ways in which this undervaluation can be rectified, including among other things, reducing the Issuers expenses, altering the Companys capital
allocation and other changes to the Issuers corporate strategy, including changes to the composition of the Board.

Based on the above discussions
with the Issuer, the Reporting Persons may (i) have discussions regarding the Issuer with other stockholders, persons that may be interested in transactions with the Company, and other interested market and industry participants; (ii) make
additional proposals to the Issuer concerning its business, management, strategic alternatives and direction; (iii) acquire additional Common Shares and/or other equity, debt, notes or other securities, including but not limited to derivative
or other instruments that are based upon or relate to the value of the Common Shares or the Issuer (collectively, Securities) in the open market or otherwise; (iv) dispose of any or all of their Securities in the open market or
otherwise; (v) nominate or recommend candidates to serve on the Board; (vi) propose or consider any one or more of the actions described in subsections (a) through (j) of Item 4 of Schedule 13D; or (vii) change their
intention with respect to any and all matters referred to in this Item 4.

Item 5. INTEREST IN SECURITIES OF THE ISSUER

(a), (b) The Reporting Persons may be deemed to beneficially
own in the aggregate 9,258,249 Common Shares. Based upon a total of 69,626,230 Common Shares outstanding as of March 2, 2016, as reported in the Issuers Proxy Statement on Schedule 14A for the Issuers 2016 annual meeting of
stockholders, filed with the Securities and Exchange Commission (the SEC) on March 18, 2016, the Reporting Persons shares represent approximately 13.30% of the outstanding Common Shares.

Carlson Capital, Asgard II, Asgard I and Mr. Carlson may be deemed to beneficially own and have the power to vote and direct the disposition of
(i) the 5,498,738 Common Shares reported herein as owned by DOF, (ii) the 1,262,697 Common Shares reported herein as owned by ROF, (iii) the 237,432 Common Shares reported herein as owned by RVC, (iv) the 367,486 Common Shares
reported herein as owned by OFF, (v) the 31,700 Common Shares reported herein as owned by SRI, (vi) the 1,509,883 Common Shares reported herein as owned by TOF, (vii) the 306,409 Common Shares reported herein as owned by ENO, and
(viii) the 43,904 Common Shares reported herein as owned by the Managed Account.

DOF may be deemed to beneficially own and has the power to vote and
dispose the 5,498,738 Common Shares reported herein as owned by it, which shares represent approximately 7.90% of the outstanding Common Shares.

ROF may
be deemed to beneficially own and has the power to vote and dispose the 1,262,697 Common Shares reported herein as owned by it, which shares represent approximately 1.81% of the outstanding Common Shares.

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