| Abbreviation | Definition |
|---|---|
| ASY | Andrews Sykes |
| ASY | Andrews Sykes Group P.L.C. Ordinary shares |
| ATAD | Oao Tatneft |
| ATC | Atlantic Coal |
| ATD | Asterand |
| ATE | Agua Terra |
| ATG | Adventis Group, P.L.C. |
| ATH | ATH Resources, P.L.C. |
| ATI | Amati Vct |
| ATI2 | Amati Vct 2 |
| ATIA | Atia Group |
| ATIA | Atia Grp |
| ATK | Atkins(ws) |
| ATL | Atlantic Global |
| ATPT | Alpha Tiger |
| ATS | Artemis Alpha |
| ATSS | Artemis Alpha P |
| ATST | Alliance Trust |
| ATY | Athelney Tst. |
| AU. | Autonomy |