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

Page 16 of 20

Page 16 of 20 – SEC Filing

RVC may be deemed to beneficially own and has the power to vote and dispose the 237,432 Common Shares reported
herein as owned by it, which shares represent approximately 0.34% of the outstanding Common Shares.

OFF may be deemed to beneficially own and has the
power to vote and dispose the 367,486 Common Shares reported herein as owned by it, which shares represent approximately 0.53% of the outstanding Common Shares.

SRI may be deemed to beneficially own and has the power to vote and dispose the 31,700 Common Shares reported herein as owned by it, which shares represent
approximately 0.05% of the outstanding Common Shares.

TOF may be deemed to beneficially own and has the power to vote and dispose the 1,509,883 Common
Shares reported herein as owned by it, which shares represent approximately 2.17% of the outstanding Common Shares.

ENO may be deemed to beneficially own
and has the power to vote and dispose the 306,409 Common Shares reported herein as owned by it, which shares represent approximately 0.44% of the outstanding Common Shares.

The Managed Account may be deemed to beneficially own and has the power to vote and dispose the 43,904 Common Shares reported herein as owned by it, which
shares represent approximately 0.06% of the outstanding Common Shares.

(c) The Reporting Persons have not effected any transactions in the Common Shares
in the last 60 days.

(d) Except as set forth herein, no person other than the Reporting Persons is known to have the right to receive or the power to
direct the receipt of dividends from, or the proceeds from the sale of, Common Shares.

(e) Not applicable.

Item 6. CONTRACT, ARRANGEMENTS, UNDERSTANDINGS OR RELATIONSHIPS WITH RESPECT TO SECURITIES OF THE ISSUER

The
Reporting Persons are parties to an agreement with respect to the joint filing of this Schedule 13D and any amendments thereto. A copy of such agreement is attached hereto as Exhibit 1 and is incorporated by reference herein.

Except as set forth herein, there are no contracts, understandings or relationships among the Reporting Persons or between the Reporting Persons and any other
person with respect to the Common Shares.

Item 7. MATERIAL TO BE FILED AS EXHIBITS
Exhibit 1 Joint Filing Agreement, dated May 4, 2016, by and among Carlson Capital, L.P., Asgard Investment Corp., Asgard Investment Corp. II, Worldwide Transactions Ltd., Black Diamond Offshore Ltd., Double Black Diamond
Offshore Ltd., Black Diamond Energy L/S Offshore Ltd., Black Diamond Thematic Offshore Ltd., Black Diamond Relative Value Offshore Ltd., Black Diamond Relative Value Cayman, L.P., Black Diamond SRI Offshore Ltd., and Clint D. Carlson.

16

Follow Archrock Inc. (NYSE:AROC)

Page 16 of 20