<PAGE>

                                                                   EXHIBIT 10.13

                             ACKNOWLEDGEMENT LETTER

THIS ACKNOWLEDGEMENT LETTER (this "LETTER") is entered into as of March 28, 2005
in the People's Republic of China ("CHINA" or "PRC") by and among the following
Parties:

(1)   SHANGHAI FOCUS MEDIA ADVERTISEMENT CO., LTD., a company of limited
      liabilities incorporated under the laws of China, with its legal address
      at F, Room 1003, No.1027, Changning Road, Changning District, Shanghai
      ("ADCO");

(2)   FOCUS MEDIA TECHNOLOGY (SHANGHAI) CO., LTD., a wholly foreign invested
      company incorporated under the laws of China, with its legal address at E,
      Room 1003, No.1027, Changning Road, Changning District, Shanghai ("FOCUS
      MEDIA");

(3)   FOCUS MEDIA DIGITAL INFORMATION TECHNOLOGY (SHANGHAI) CO., LTD., a company
      of limited liabilities incorporated under the laws of China, with its
      legal address at Room A72, Floor 28, No.369, Jiangsu Road, Changning
      District, Shanghai ("TECHCO"); and

(4)   LOCAL ADVERTISING SUBSIDIARIES listed in Appendix 1 hereof (the "ADCO
      SUBSIDIARIES").

(In this Letter, AdCo, Focus Media and AdCo Subsidiaries may hereinafter be
individually or collectively referred to as the "TRANSFEROR(S)", while TechCo,
as the "TRANSFEREE"; the Transferor(s) and Transferee shall hereinafter be
referred to collectively as "PARTIES", and a "PARTY" individually.)

WHEREAS: The Transferee acquired the relevant equipment from the Transferors on
October 30, 2004.

NOW, THEREFORE, in order to specify the rights and obligations of the Parties in
respect of issue of the above equipment transfer, the Parties hereby acknowledge
as follows:

1.    The Parties hereby acknowledge that the Transferors transferred to the
      Transferee on October 30, 2004, and the Transferee acquired from the
      Transferors on October 30, 2004 (the "CLOSING DATE"), the equipment listed
      in Appendix 2 hereof (the "TRANSFERRED EQUIPMENT").

2.    The Parties hereby acknowledge that, since the Closing Date, the ownership
      and related risks of the Transferred Equipment have all been transferred
      together to the Transferee, and the Transferee has since then acquired the
      sound, legal and immaculate ownership to the Transferred Equipment.

3.    According to the Evaluation Report (document Hu Xin Ping Bao Zi [2004] No.
      0046) issued by Shanghai Xin Da Asset Evaluation Co., Ltd. dated November
      25, 2004, as of the date October 31, 2004, the book value of the
      Transferred Equipment (including fixed assets and inventory) is Renminbi
      fifty-seven million four hundred thousand eight hundred and ten point five
      seven (RMB57,400,810.57), and its evaluated value is Renminbi seventeen
      million eight hundred ninety one thousand five hundred and seventy two
      point zero four (RMB17,891,572.04). On the basis of the above

10.25

                                       1

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      evaluation result, the Parties agree and acknowledge that the transfer
      price payable by the Transferee to the Transferors for the transfer of the
      Transferred Equipment shall be Renminbi seventeen million eight hundred
      ninety one thousand five hundred and seventy two point zero four
      (RMB17,891,572.04) (the "TRANSFER PRICE") in total.

4.    The Transferors hereby acknowledge that they have already reviewed and
      understood the whole text of this Letter in all aspects, have been given
      the opportunity to seek professional legal opinion thereto, and have
      accepted the Transfer Price out of their own accord as the reasonable,
      full and appropriate consideration for the acquisition by the Transferee
      of the Transferred Equipment.

5.    The Transferors hereby acknowledge that the Transferee has already
      performed its payment obligation in respect of the Transfer Price; in
      respect of the Transferred Equipment, the Transferee has no obligation
      whatsoever to further pay any amount to the Transferors for its
      entitlement to the sound, legal and immaculate ownership to the
      Transferred Equipment.

6.    The Parties hereby acknowledge that they have already duly performed their
      respective obligations in respect of the transfer of the Transferred
      Equipment, and there is no default in existence.

7.    This Acknowledge Letter is executed in eleven (11) original copies, with
      each Party holding one (1) copy hereof.

IN WITNESS HEREOF, this Acknowledgement Letter is executed by the Parties below
at the date and the place set forth first above.

                   [the remainder of this page is left blank]

Acknowledgment Letter

                                       2

<PAGE>

EXECUTION PAGE

SHANGHAI FOCUS MEDIA ADVERTISEMENT CO., LTD. (Corporate Seal)

Signed by: /s/ Jason Nanchun Jiang
           --------------------------------------------------
Name: Jason Nanchun Jiang
Position: Authorized Representative

FOCUS MEDIA TECHNOLOGY (SHANGHAI) CO., LTD. (Corporate Seal)

Signed by: /s/ Jason Nanchun Jiang
           --------------------------------------------------
Name: Jason Nanchun Jiang
Position: Authorized Representative

SICHUAN FOCUS MEDIA ADVERTISING AGENCY CO., LTD. (Corporate Seal)

Signed by: /s/ Jason Nanchun Jiang
           --------------------------------------------------
Name: Jason Nanchun Jiang
Position: Authorized Representative

ZHEJIANG RUIHONG FOCUS MEDIA CULTURE COMMUNICATIONS CO., LTD. (Corporate Seal)

Signed by: /s/ Jason Nanchun Jiang
           --------------------------------------------------
Name: Jason Nanchun Jiang
Position: Authorized Representative

CHONGQING GEYANG FOCUS MEDIA CULTURE COMMUNICATIONS CO., LTD. (Corporate Seal)

Signed by: /s/ Jason Nanchun Jiang
           --------------------------------------------------
Name: Jason Nanchun Jiang
Position: Authorized Representative

CHANGSHA FOCUS MEDIA CENTURY ADVERTISING CO., LTD. (Corporate Seal)

Signed by: /s/ Du Kang
           --------------------------------------------------
Name: Du Kang
Position: Authorized Representative

QINGDAO FOCUS MEDIA ADVERTISING AGENCY CO., LTD. (Corporate Seal)

Signed by: /s/ Zhang Junyan
           --------------------------------------------------
Name: Zhang Junyan
Position: Authorized Representative

Acknowledgment Letter

                                       3

<PAGE>

DALIAN FOCUS MEDIA ADVERTISING AGENCY CO., LTD. (Corporate Seal)

Signed by: /s/ Xie Haobo
           --------------------------------------------------
Name: Xie Haobo
Position: Authorized Representative

YUNNAN FOCUS MEDIA CO., LTD. (Corporate Seal)

Signed by: /s/ Jason Nanchun Jiang
           --------------------------------------------------
Name: Jason Nanchun Jiang
Position: Authorized Representative

WUHAN GESHI FOCUS MEDIA ADVERTISING CO., LTD. (Corporate Seal)

Signed by: /s/ Jason Nanchun Jiang
           --------------------------------------------------
Name: Jason Nanchun Jiang
Position: Authorized Representative

TRANSFEREE:

FOCUS MEDIA DIGITAL INFORMATION TECHNOLOGY (SHANGHAI) CO., LTD. (Corporate Seal)

Signed by: /s/ Jason Nanchun Jiang
           --------------------------------------------------
Name: Jason Nanchun Jiang
Position: Authorized Representative

Acknowledgment Letter

                                       4

<PAGE>

                         APPENDIX 1 - ADCO SUBSIDIARIES

<TABLE>
<CAPTION>
                        COMPANY NAME                                                    ADDRESS
--------------------------------------------------------------  ------------------------------------------------------
<S>                                                             <C>
Sichuan Focus Media Advertising Agency Co., Ltd.                1-1-6-603, No. 151 Kehua Road (N), Wuhou District, Chengdu

Zhejiang Ruihong Focus Media Culture Communications Co., Ltd.   Room 909, Building C, Hualong Century Plaza, No. 18 Hangda Road

Chongqing Geyang Focus Media Culture Communications Co., Ltd.   Room 25-3, Building A, Shidai Garden, No. 3 Qingnian Road,
                                                                Yuzhong District, Chongqing

Changsha Focus Media Century Advertising Co., Ltd.              New Century City, No. 692 Furong Road (M), Changsha

Qingdao Focus Media Advertising Agency Co., Ltd.                Room 5, Floor 12, Building 1, No. 37 Donghai Road, Shinan District,
                                                                Qingdao

Dalian Focus Media Advertising Agency Co., Ltd.                 Room 1309, Hongfu Building, No. 45 Shanghai Road, Zhongshan
                                                                District, Dalian

Yunnan Focus Media Co., Ltd.                                    Floor 17, Dade Building, Jinbi Road, Kunming

Wuhan Geshi Focus Media Advertising Co., Ltd.                   Room 1602, Building AI, Apartment Building, Wuhan Plaza, No. 688
                                                                Jiafang Avenue, Wuhan
</TABLE>


Acknowledgment Letter

                                       5

<PAGE>

                APPENDIX 2 - DETAILS OF THE TRANSFERRED EQUIPMENT

10.25

                                       6