| Abbreviation | Definition |
|---|---|
| ATLCU | Atlantic Pharmaceuticals, Inc. |
| ATLCW | Atlantic Pharmaceuticals, Inc. Warrants |
| ATLKY | Atlas Copco, A. B. |
| ATLPP | Atlantic Capital Corporation Preferred |
| ATLRS | Atlantic Realty Trust |
| ATMI | A T M I, Inc. |
| ATML | Atmel Corporation |
| ATMS | Tidel Technology, Inc. |
| ATOM | Atomic Burrito, Inc. (delisted) |
| ATON | Alteon Web Systems (delisted) |
| ATPC | Athey Products Corporation |
| ATPX | Advanced Technology Products, Inc. |
| ATRC | Auto- Trol Technology Corporation (delisted) |
| ATRI | Atrion Corporation |
| ATRM | Aetrium, Inc. |
| ATRO | Astronics Corporation |
| ATROB | Astronics Corporation Class B |
| ATRX | Atrix Labs, Inc. |
| ATSI | A T S Medical, Inc. |
| ATSM | A T S Money Systems, Inc. |