<PAGE>

                                                                   EXHIBIT 10.73

                    Equity Pledge Agreement-Participation Letter of Hefei Fukesi

                   ACKNOWLEDGEMENT LETTER FOR PARTICIPATION OF
                             EQUITY PLEDGE AGREEMENT

SHANGHAI FOCUS MEDIA ADVERTISEMENT CO., LTD., (registered address: Room 1003 F,
No.1027, Changning Road, Changning District, Shanghai) and SHANGHAI FOCUS MEDIA
ADVERTISING AGENCY CO., LTD., (registered address: Room A65, 28 Floor,
No.369, Jiangsu Road, Changning District, Shanghai) (hereinafter the
"PARTICIPATED PLEDGOR"), and HEFEI FUKESI ADVERTISING CO., LTD. (registered
address: Room 2401B, Gujin Baihua Building, No. 156 Shouchun Road, Hefei)
(hereinafter the "PARTICIPATED TARGET COMPANY"), hereby agree to participate in
Equity Pledge Agreement dated on March 28, 2005 between Focus Media Technology
(Shanghai) Co., Ltd. (hereinafter "FOCUS MEDIA Technology"), Focus Media Digital
Information Technology (Shanghai) Co, Ltd. (hereinafter "FOCUS MEDIA DIGITAL"),
Shanghai Focus Media Advertisement Co., Ltd. and other relevant parties
(hereinafter the "EQUITY PLEDGE Agreement") as an independent contract party.
The Participated Pledgor and the Participated Target Company hereby agree to
pledge the equity of the Participated Target Company which constitutes 100% of
the registered capital of the Participated Target Company to Focus Media
Technology as of the date of this Acknowledgement Letter to secure the following
contractual obligations:

1.    Contractual Obligation for the Participated Pledgor:

(a)   Contractual Obligation under the Call Option Agreement among Focus Media
      Technology and other relevant parties dated March 28 2005 (hereinafter the
      "CALL OPTION AGREEMENT") participated by the Pledgor pursuant to the
      Acknowledge Letter executed by the Participated Pledgor on the date May
      22, 2006; and

(b)   Contractual Obligation under the Shareholder's Voting Rights Proxy
      Agreement among Focus Media Technology and other relevant parties dated
      March 28 2005

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                    Equity Pledge Agreement-Participation Letter of Hefei Fukesi

      (hereinafter the "PROXY AGREEMENT") participated by the Pledgor pursuant
      to the Acknowledge Letter executed by the Participated Pledgor on the date
      May 22, 2006.

2.    Contractual Obligation for the Participated Target Company:

(a)   Contractual Obligation under the Call Option Agreement participated by the
      Target Company pursuant to the Acknowledge Letter executed by the
      Participated Target Company on the date May 22, 2006; and

(b)   Contractual Obligation under the Proxy Agreement participated by the
      Target Company pursuant to the Acknowledge Letter executed by the
      Participated Target Company on the date May 22, 2006.

This Acknowledgement Letter once executed by the Participated Pledgor and
Participated Target Company, the Participated Pledgor and the Participated
Target Company shall make the same undertakings and warranties with those of
Pledgors and Target Companies under the Equity Pledge Agreement (to the extent
that is related and applicable to Participating Shareholder and Participated
Target Company), agree to perform the obligations of Pledgors and Target
Companies stipulated in the Equity Pledge Agreement (to the extent that is
related and applicable to Participating Shareholder and Participated Target
Company), and admit the rights and obligations of Parties under the Equity
Pledge Agreement.

                   [THE REMAINDER OF THIS PAGE IS LEFT BLANK]

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                    Equity Pledge Agreement-Participation Letter of Hefei Fukesi

                                [EXECUTION PAGE]

SHANGHAI FOCUS MEDIA ADVERISEMENT CO., LTD.
(Company chop)

Signature by: /s/ Jason Nanchun Jiang
              --------------------------
Name: Jason Nanchun Jiang
Position: Authorized Representative
Date: May 22, 2006

SHANGHAI FOCUS MEDIA ADVERTISING AGENCY CO., LTD.
(Company chop)

Signature by: /s/ Jason Nanchun Jiang
              --------------------------
Name: Jason Nanchun Jiang
Position: Authorized Representative
Date: May 22, 2006

HEFEI FUKESI ADVERTISING CO., LTD.
(Company chop)

Signature by: /s/ Jason Nanchun Jiang
              --------------------------
Name: Jason Nanchun Jiang
Position: Authorized Representative
Date: May 22, 2006

FOCUS MEDIA TECHNOLOGY (SHANGHAI) CO., LTD.
(Company chop)

Signature by: /s/ Jason Nanchun Jiang
              --------------------------
Name: Jason Nanchun Jiang
Position: Authorized Representative
Date: May 22, 2006

FOCUS MEDIA DIGITAL INFORMATION TECHNOLOGY (SHANGHAI) CO, LTD.
(Company chop)

Signature by: /s/ Jason Nanchun Jiang
              --------------------------
Name: Jason Nanchun Jiang
Position: Authorized Representative
Date: May 22, 2006