UNITED STATES
                       SECURITIES AND EXCHANGE COMMISSION
                              WASHINGTON, DC 20549

                                  SCHEDULE 13G

                    Under the Securities Exchange Act of 1934
                                (Amendment No. )*


                         Core-Mark Holding Company, Inc.
--------------------------------------------------------------------------------
                                (Name of Issuer)


                     Common Stock, par value $0.01 per share
--------------------------------------------------------------------------------
                         (Title of Class of Securities)


                                    218681140
--------------------------------------------------------------------------------
                                 (CUSIP Number)


                                December 13, 2005
--------------------------------------------------------------------------------
             (Date of Event Which Requires Filing of this Statement)


          Check the appropriate box to designate the rule pursuant to which this
Schedule is filed:

          [_] Rule 13d-1(b)

          [X] Rule 13d-1(c)

          [_] Rule 13d-1(d)

----------

*    The  remainder  of this  cover  page  shall be filled  out for a  reporting
     person's  initial  filing on this form with respect to the subject class of
     securities,  and for any subsequent amendment containing  information which
     would alter the disclosures provided in a prior cover page.

          The information required in the remainder of this cover page shall not
be deemed to be "filed" for the purpose of Section 18 of the Securities Exchange
Act of 1934 ("Act") or otherwise  subject to the  liabilities of that section of
the Act but shall be subject to all other  provisions of the Act  (however,  see
the Notes).



CUSIP No.   218681104
            ---------------------


1. NAME OF REPORTING PERSONS
     I.R.S. IDENTIFICATION NOS. OF ABOVE PERSONS (ENTITIES ONLY)

     Ian G. Wallace

2. CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP (SEE INSTRUCTIONS)
                                                                 (a) [_]
                                                                 (b) [X]

3. SEC USE ONLY



4. CITIZENSHIP OR PLACE OF ORGANIZATION

     United States of America

NUMBER OF SHARES BENEFICIALLY OWNED BY EACH REPORTING PERSON WITH

5. SOLE VOTING POWER

     0

6. SHARED VOTING POWER

     736,564

7. SOLE DISPOSITIVE POWER

     0

8. SHARED DISPOSITIVE POWER

     736,564

9. AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON

     736,564

10.  CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES (SEE
     INSTRUCTIONS)

                                                                      [_]

11. PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW 9

     7.4%

12. TYPE OF REPORTING PERSON (SEE INSTRUCTIONS)

     IN

--------------------------------------------------------------------------------



CUSIP No.    218681104
            ---------------------


1. NAME OF REPORTING PERSONS
     I.R.S. IDENTIFICATION NOS. OF ABOVE PERSONS (ENTITIES ONLY)

     River Run Management, L.L.C.

2. CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP (SEE INSTRUCTIONS)
                                                                 (a) [_]
                                                                 (b) [X]

3. SEC USE ONLY



4. CITIZENSHIP OR PLACE OF ORGANIZATION

     Delaware

NUMBER OF SHARES BENEFICIALLY OWNED BY EACH REPORTING PERSON WITH

5. SOLE VOTING POWER

     0

6. SHARED VOTING POWER

     736,564

7. SOLE DISPOSITIVE POWER

     0

8. SHARED DISPOSITIVE POWER

     736,564

9. AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON

     736,564

10. CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES (SEE
     INSTRUCTIONS)

                                                                      [_]

11. PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW 9

     7.4%

12. TYPE OF REPORTING PERSON (SEE INSTRUCTIONS)

     OO, IA

--------------------------------------------------------------------------------



CUSIP No.   218681104
            ---------------------


Item 1(a).  Name of Issuer:


            Core-Mark Holding Company, Inc.
            --------------------------------------------------------------------

      (b). Address of Issuer's Principal Executive Offices:


                      395 Oyster Point Boulevard, Suite 415
                      South San Francisco, California 94080
            --------------------------------------------------------------------


Item 2(a).  Names of Persons Filing:


            Ian G. Wallace
            River Run Management, L.L.C.
            --------------------------------------------------------------------

      (b). Address of Principal Business Office, or if None, Residence:

            Ian G. Wallace                          River Run Management, L.L.C.
            c/o 152 West 57th Street                c/o 152 West 57th Street
            52nd Floor                              52nd Floor
            New York, New York 10019                New York, New York 10019

            --------------------------------------------------------------------

      (c). Citizenship:

                     Ian G. Wallace - United States of America
                     River Run Management, L.L.C. - Delaware
            --------------------------------------------------------------------

      (d). Title of Class of Securities:


          Common Stock, par value $0.01 per share
            --------------------------------------------------------------------

      (e). CUSIP Number:


            218681104
            --------------------------------------------------------------------


Item 3.   If This Statement is filed pursuant to ss.240.13d-1(b) or
            240.13d-2(b), or (c), check whether the person filing is a:

     (a)       [_] Broker or dealer registered under Section 15 of the Exchange
               Act (15 U.S.C. 78c).

     (b)       [_] Bank as defined in Section 3(a)(6) of the Exchange Act (15
               U.S.C. 78c).

     (c)       [_] Insurance company as defined in Section 3(a)(19) of the
               Exchange Act (15 U.S.C. 78c).

     (d)       [_] Investment company registered under Section 8 of the
               Investment Company Act of 1940 (15 U.S.C. 80a-8).

     (e)       [_] An investment adviser in accordance with
               s.240.13d-1(b)(1)(ii)(E);

     (f)       [_] An employee benefit plan or endowment fund in accordance with
               s.240.13d-1(b)(1)(ii)(F);

     (g)       [_] A parent holding company or control person in accordance with
               Rule 13d-1(b)(1)(ii)(G);

     (h)       [_] A savings association as defined in Section 3(b) of the
               Federal Deposit Insurance Act (12 U.S.C.1813);

     (i)       [_] A church plan that is excluded from the definition of an
               investment company under Section 3(c)(14) of the Investment
               Company Act of 1940 (15 U.S.C. 80a-3);

     (j)       [_] Group, in accordance with s.240.13d-1(b)(1)(ii)(J).

Item 4.  Ownership.

          Provide the following  information  regarding the aggregate number and
percentage of the class of securities of the issuer identified in Item 1.

     (a) Amount beneficially owned:

          Ian G. Wallace - 736,564
          River Run Management, L.L.C. - 736,564

          ----------------------------------------------------------------------

     (b) Percent of class:

          Ian G. Wallace - 7.4%
          River Run Management, L.L.C. - 7.4%

     (c) Number of shares as to which the person has:


          Ian G. Wallace

          (i)  Sole power to vote or to direct the vote 0



          (ii) Shared power to vote or to direct the vote 736,564



          (iii) Sole power to dispose or to direct the disposition of 0


          (iv) Shared power to dispose or to direct the disposition of 736,564


          River Run Management, L.L.C.

          (i)  Sole power to vote or to direct the vote 0



          (ii) Shared power to vote or to direct the vote 736,564



          (iii) Sole power to dispose or to direct the disposition of 0


          (iv) Shared power to dispose or to direct the disposition of 736,564

         -----------------------------------------------------------------------
Item 5.  Ownership of Five Percent or Less of a Class.

          If this  statement  is being  filed to report  the fact that as of the
date hereof the reporting  person has ceased to be the beneficial  owner of more
than five percent of the class of securities, check the following [ ].

         -----------------------------------------------------------------------


Item 6.  Ownership of More Than Five Percent on Behalf of Another Person.

          If any other person 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, such
securities,  a statement  to that effect  should be included in response to this
item and, if such interest relates to more than five percent of the class,  such
person  should be  identified.  A listing of the  shareholders  of an investment
company registered under the Investment Company Act of 1940 or the beneficiaries
of employee benefit plan, pension fund or endowment fund is not required.

                          Ian G. Wallace is the managing member of River Run
                          Management, L.L.C. and River Run Capital, L.L.C., both
                          of which are Delaware limited liability companies that
                          serve as the investment manager and general partner,
                          respectively, to, and exercise investment discretion
                          over the accounts of, a number of investment vehicles.
                          None of those investment vehicles has beneficial
                          ownership of 5% or more of the class of Common Stock.
         -----------------------------------------------------------------------


Item 7.  Identification and Classification of the Subsidiary Which Acquired
         the Security Being Reported on by the Parent Holding Company or Control
         Person.

          If a parent holding company or Control person has filed this schedule,
pursuant to Rule  13d-1(b)(1)(ii)(G),  so indicate under Item 3(g) and attach an
exhibit  stating the  identity  and the Item 3  classification  of the  relevant
subsidiary.  If a parent  holding  company  or  control  person  has filed  this
schedule  pursuant to Rule 13d-1(c) or Rule 13d-1(d),  attach an exhibit stating
the identification of the relevant subsidiary.

                     Not applicable.
         -----------------------------------------------------------------------


Item 8.  Identification  and  Classification  of Members of the Group.

          If    a    group    has    filed    this    schedule    pursuant    to
ss.240.13d-1(b)(1)(ii)(J),  so  indicate  under  Item 3(j) and attach an exhibit
stating the identity and Item 3 classification of each member of the group. If a
group has filed this schedule pursuant to  ss.240.13d-1(c)  or  ss.240.13d-1(d),
attach an exhibit stating the identity of each member of the group.

                     Not applicable.
         -----------------------------------------------------------------------


Item 9.  Notice of Dissolution of Group.

          Notice  of  dissolution  of a group  may be  furnished  as an  exhibit
stating the date of the dissolution and that all further filings with respect to
transactions in the security reported on will be filed, if required,  by members
of the group, in their individual capacity. See Item 5.

                     Not applicable.
          ----------------------------------------------------------------------

Item 10.  Certification.


          By signing below I certify that, to the best of my knowledge and
          belief, the securities referred to above were not acquired and are not
          held for the purpose of or with the effect of changing or influencing
          the control of the issuer of the securities and were not acquired and
          are not held in connection with or as a participant in any transaction
          having such purpose or effect.



                                    SIGNATURE

          After reasonable inquiry and to the best of my knowledge and belief, I
certify that the information  set forth in this statement is true,  complete and
correct.


Date: February 10, 2006
                                                 /s/ Ian G. Wallace*
                                                 -----------------------------
                                                     Ian G. Wallace



                                                 River Run Management, L.L.C.*

                                                 By: /s/ Ian G. Wallace
                                                     ------------------------
                                                 Name: Ian G. Wallace
                                                 Title: Managing Member


* The  Reporting  Persons  disclaim  beneficial  ownership in the Common  Stock,
except to the extent of their pecuniary interest therein.

The  original  statement  shall be signed by each  person  on whose  behalf  the
statement is filed or his authorized representative.  If the statement is signed
on behalf of a person by his authorized  representative  other than an executive
officer  or   general   partner  of  the   filing   person,   evidence   of  the
representative's  authority to sign on behalf of such person shall be filed with
this statement,  provided,  however, that a power of attorney,  for this purpose
which is already on file with the Commission may be  incorporated  by reference.
The name and any title of each person who signs the statement  shall be typed or
printed beneath his signature.

Note.  Schedules  filed in paper format shall include a signed original and five
copies of the  schedule,  including  all  exhibits.  See  s.240.13d-7  for other
parties for whom copies are to be sent.

Attention.  Intentional  misstatements  or omissions of fact constitute  federal
criminal violations (see 18 U.S.C. 1001).


                                                                       Exhibit A


                                    AGREEMENT

The undersigned agree that this Schedule 13G dated December 13, 2006 relating to
the Common Stock, par value $0.01 per share of Core-Mark Holding Company,  Inc.,
shall be filed on behalf of the undersigned.




                                                 /s/ Ian G. Wallace*
                                                 -----------------------------
                                                    Ian G. Wallace





                                                 River Run Management, L.L.C.*

                                                 By: /s/ Ian G. Wallace
                                                     ------------------------
                                                 Name: Ian G. Wallace
                                                 Title: Managing Member






SK 02642 0001 642338