UPDATE: 21Vianet Group, Inc. Announces Receipt of Preliminary Non-Binding "Going Private" Proposal, $23/ADS

21Vianet Group, Inc.

("21Vianet" or the "Company"), a leading carrier-neutral internet data center services provider in China, announced that its Board of Directors (the "Board") has received a non-binding proposal letter, dated June 10, 2015, from Mr. Josh Sheng Chen ("Mr. Chen"), Chairman of the Board and Chief Executive Officer of the Company, Kingsoft Corporation Limited ("Kingsoft") and Tsinghua Unigroup International Co., Ltd. ("Unigroup", together with Mr. Chen and Kingsoft, the "Buyer Group"), proposing a "going-private" transaction (the "Transaction") to acquire all of the outstanding ordinary shares of the Company not already owned by the Buyer Group for US$23.00 in cash per American depositary share ("ADSs"), or approximately US$3.83 per ordinary share, which represents approximately a 17.7% premium above the average closing price of the Company's ADSs over the last 15 trading days up to and including June 9, 2015. An English translation of the proposal letter is attached hereto as Annex A. The Board intends to form a special committee consisting of independent directors to consider this proposal. The Board cautions the Company's shareholders and others considering trading in its securities that the Board just received the non-binding proposal letter from the Buyer Group and no decisions have been made with respect to the Company's response to the Transaction. There can be no assurance that any definitive offer will be made, that any agreement will be executed or that this or any other transaction will be approved or consummated. The Company does not undertake any obligation to provide any updates with respect to this or any other transaction, except as required under applicable law.