SCHEDULE 13D/A

21Vianet Group, Inc.

Class A Ordinary Shares, par value US$0.00001 per share · CUSIP: G91458102

Event date: 2025-03-17

Reporting persons may disclose overlapping interests. Their amounts are shown individually and are not added into a filing total.

Filing-level shares

Unavailable

Percent of class

Unavailable

• Vector Holdco Pte. Ltd.

  Shares: 201,070,641 · Class: 12.1%

• BTO Vector Fund ESC (CYM) L.P.

  Shares: 268,800 · Class: 0.02%

• BTO Vector Fund FD (CYM) L.P.

  Shares: 5,618,794 · Class: 0.3%

• BTO Super Holding (NQ) Co. III Pte. Ltd.

  Shares: 201,070,641 · Class: 12.1%

• Blackstone Tactical Opportunities SG II (Cayman) - NQ L.P.

  Shares: 201,070,641 · Class: 12.1%

• BTO Holdings (Cayman) - NQ Manager L.L.C.

  Shares: 5,887,594 · Class: 0.3%

• Blackstone Tactical Opportunities Management Associates (Cayman) - NQ L.P.Reported CIK 0001758419

  Shares: 206,958,235 · Class: 12.5%

• BTO GP-NQ L.L.C.

  Shares: 206,958,235 · Class: 12.5%

• Blackstone Tactical Opportunities LR Associates (Cayman) - NQ Ltd.

  Shares: 206,958,235 · Class: 12.5%

• Blackstone Holdings IV L.P.

  Shares: 206,958,235 · Class: 12.5%

• Blackstone Holdings IV GP L.P.

  Shares: 206,958,235 · Class: 12.5%

• Blackstone Holdings IV GP Management (Delaware) L.P.

  Shares: 206,958,235 · Class: 12.5%

• Blackstone Holdings IV GP Management L.L.C.

  Shares: 206,958,235 · Class: 12.5%

• Blackstone Inc.

  Shares: 206,958,235 · Class: 12.5%

• Blackstone Group Management L.L.C.

  Shares: 206,958,235 · Class: 12.5%

• Stephen A. Schwarzman

  Shares: 206,958,235 · Class: 12.5%

Amounts are as disclosed in this filing. Schedule type alone does not establish investment intent.