- 1 800 BLODAU COM
- Genomeg 10X Inc.
- 1 & 1 AG
- Gofal Iechyd 1Life Inc.
- Grŵp 22ain Ganrif Inc.
- 2U Inc.
- 360 Cyllid Inc.
- Systemau 3D Corp.
- Grŵp 3i PLC
- 3i Seilwaith PLC
- 3M
- 3SBio Inc.
- 51 Swydd Inc.
- 58.com Inc.
- 888 Daliad
- 8x8 Inc.
- 9F Inc.
- AO Smith Corp.
- AP Moller Maersk
- Grŵp A2A
- AA CCC
- AAC Technologies Holdings Inc.
- AAK AB
- Alberts NV
- Banc Aareal
- ABB CYF
- Labordai Abbott
- AbbVie Inc.
- Abengoa B.
- Cwmni Abercrombie & Fitch
- Rheoli Asedau Aberdeen
- Abertis
- ABIOMED Inc.
- Diwydiannau ABM Inc.
- Grŵp ABN AMRO NV
- AM CHI Yn Dal AG
- abrdn PLC
- Cyfathrebu Acacia Inc.
- Mwyngloddio Acacia PLC
- ACADIA Pharmaceuticals Inc.
- Ymddiriedolaeth Acadia Realty
- Acasti Pharma Inc.
- Accenture PLC
- Acciona
- Accor SA
- Accuray Inc.
- Mae AcelRx Pharmaceuticals Inc.
- Acerinox SA
- Ackermans & Van Haaren NV
- Ymchwil ACM Inc.