[21Vianet Group, Inc. Reports Second Quarter 2015 Unaudited Financial Results 2Q15 Net Revenues Up 31.7% YOY to RMB866.8 Million 2Q15 Adjusted EBITDA Up 13.2% YOY to RMB149.4 Million Live Conference Call to be Held at 8:00 PM U.S. Eastern Time, August 26, 2015 BEIJING, August 26, 2015 (GLOBE NEWSWIRE) — 21Vianet Group, Inc. (Nasdaq: VNET) (“21Vianet” or the “Company”), a] [FORM 6-K 21Vianet Group, Inc. M5, 1 Jiuxianqiao East Road, Chaoyang District Beijing 100016 The People’s Republic of China (86 10) 8456 2121 x ¨ Form 20-F ¨ ¨ 21Vianet Group, Inc. By : Name : Terry Wang Title : Chief Financial Officer 6-K 1 d67575d6k.htm FORM 6-K]

[FORM 6-K 21Vianet Group, Inc. M5, 1 Jiuxianqiao East Road, Chaoyang District Beijing 100016 The People’s Republic of China (86 10) 8456 2121 x ¨ Form 20-F ¨ ¨ Departure of an Executive Officer Mr. Philip Lin recently resigned as the executive vice president of strategy and business development of 21Vianet Group, Inc., effectively immediately. 21Vianet Group, Inc. Sheng Chen]

[21VIANET GROUP ANNOUNCES APPOINTMENT OF FINANCIAL ADVISOR AND LEGAL COUNSELS BEIJING, July 9, 2015 (GLOBE NEWSWIRE) — 21Vianet Group, Inc. (Nasdaq:VNET) (“21Vianet” or the “Company”), a leading carrier-neutral Internet data center services provider in China, today announced that the special committee of its board of directors (the “Special Committee”) has retained Morgan Stanley Asia Limited as its financial advisor, K&L] [FORM 6-K 21Vianet Group, Inc. M5, 1 Jiuxianqiao East Road, Chaoyang District Beijing 100016 The People’s Republic of China (86 10) 8456 2121 x ¨ Form 20-F ¨ ¨ 21Vianet Group, Inc. By Terry Wang Chief Financial Officer 6-K 1 d51463d6k.htm FORM 6-K]

[21Vianet Group, Inc. Announces Change in Leadership Team BEIJING, China, June 22, 2015 — 21Vianet Group, Inc. (Nasdaq: VNET) (“21Vianet” or the “Company”), a leading carrier-neutral internet data center services provider in China, today announced that Mr. Shang-Wen Hsiao, its Chief Financial Officer, has decided to resign from his current role and will serve as an advisor to the Board] [FORM 6-K 21Vianet Group, Inc. M5, 1 Jiuxianqiao East Road, Chaoyang District Beijing 100016 The People’s Republic of China (86 10) 8456 2121 x ¨ Form 20-F ¨ ¨ 21Vianet Group, Inc. Sheng Chen Chairman and Chief Executive Officer 6-K 1 d946376d6k.htm FORM 6-K]