| Abbreviation | Definition |
|---|---|
| ATBC | Athens Bancshares Corporation |
| ATCC | Astrocom Corporation |
| ATCH | Arthur Treachers, Inc. (de-listed) |
| ATCO | American Technology Corporation |
| ATEA | Astea International, Inc. |
| ATEC | A T E C Group, Inc. |
| ATEG | American Technology Group |
| ATEK | Alternative Technology Resources, Inc. |
| ATEX | Avery Communications |
| ATGC | A T G, Inc. |
| ATGI | Alpha Technology Group, Inc. |
| ATGN | Altigen Communications |
| ATHM | At Home Corporation |
| ATHO | Amco Transport Holdings, Inc. |
| ATHO | Amco Transport Holdings, Incorporated (de-listed) |
| ATHO | Amco Transport Holdings, Incorporated (de-listed) |
| ATHY | Applied Theory Corporation |
| ATIL | Atlantis International Corporation |
| ATIS | Advanced Tissue Sciences |
| ATLC | Atlantic Pharmaceuticals, Inc. |