Exhibit 4.40

Agreement

This Agreement
(this Agreement) is entered into by and among the parties below as of December 28, 2013 in Shenzhen, Peoples Republic of China (PRC):

500.COM LIMITED (500.COM), a company established and existing under the laws of Cayman Islands, with its address at
Floor 4, Willow House, Cricket Square, P.O. Box 2804, Grand Cayman;

E-Sun Sky Computer (Shenzhen) Co., Ltd. (E-Sun Sky
Computer), a wholly foreign owned enterprise, established and existing under the laws of the PRC, with its address at Room 3-A, Complex Building (including affiliated equipment room), Shenxianling Sports Center, Central City, Longgang
District, Shenzhen;

Wang Ying, a Chinese citizen with Chinese Identification No.: 422801198308030625.

The above parties shall be collectively referred to as the Parties.

Whereas:



|A. | Wang Ying is a shareholder of Shenzhen Guangtiandi Technology Co., Ltd. (a limited liability company established and existing under the laws of the PRC, with its address at Room 2-A (only for business purposes),
Complex Building (including affiliated equipment room), Shenxianling Sports Center, Central City, Longgang District, Shenzhen, Guangtiandi);
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|B. | E-Sun Sky Computer is a subsidiary wholly owned by 500.COM in Shenzhen, PRC;
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The Parties hereby acknowledge
certain financial and other matters regarding Guangtiandi as follows:



|1. | 500.COM acknowledges and undertakes that, since the date of this Agreement (Effective Date), when needed by Guangtiandi, 500.COM agrees to provide unconditional financial support, either by itself or
through its wholly-owned subsidiary in ChinaE-Sun Sky Computer, to Wang Ying in ways permitted by the PRC laws and regulations (Financial Support). Wang Ying agrees to accept such Financial Support in ways permitted by the
PRC laws and regulations and undertakes to use unconditionally such Financial Support only for providing funds to Guangtiandi so as to develop its business.
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|2. | If 500.COM provides Financial Support by itself or through E-Sun Sky Computer, the repayment due date and method will be negotiated and determined by the Parties separately. To the extent permitted by the PRC laws and
other applicable laws, if Wang Ying exempts the repayment obligations of Guangtiandi as needed by Guangtiandi, 500.COM agrees, either by itself or by instructing E-Sun Sky Computer, to exempt the repayment obligations of Wang Ying.
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|3. | Wang Ying agrees that, to the extent permitted by the PRC laws and other applicable laws, if needed by Guangtiandi, Wang Ying may exempt the repayment obligations of Guangtiandi.
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|4. | E-Sun Sky Computer and Wang Ying hereby agree and acknowledge that, since the Effective Date, the agreement entered into by and between E-Sun Sky Computer and Wang Ying on June 1, 2011 (Original Financial
Support Agreement) shall be terminated. The rights and obligations of E-Sun Sky Computer and Wang Ying under the Original Financial Support Agreement shall be terminated, and the rights and obligations under the Original Financial Support
Agreement that have not been performed shall no longer be performed. The rights and obligations that have already been performed under the Original Financial Support Agreement shall not be affected by the termination of the Original Financial
Support Agreement.
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|                |  |                   
|--------------- |  | ------------------
|500.COM LIMITED
|                | 
|By:             |  | /s/    Man San Law
|Name:           |  | Man San Law       
|Title:          |  | Director          



|                                        |  |                     
|--------------------------------------- |  | --------------------
|E-Sun Sky Computer (Shenzhen) Co., Ltd.
|                                        | 
|By:                                     |  | /s/    Geng Jin     
|Name:                                   |  | Geng Jin            
|Title:                                  |  | Legal Representative



|          |  |                 
|--------- |  | ----------------
|Wang Ying
|          | 
|By:       |  | /s/    Wang Ying