| Abbreviation | Definition |
|---|---|
| ALOT | Astro Med, Inc. |
| ALOY | Alloy Online, Inc. |
| ALPH | Alphanet Solutions, Inc. |
| ALPVE | Alabama Power Company (now ALQ) |
| ALRC | Alternative Resource Corporation |
| ALRE | Annuity & Life Re, LTD. |
| ALSC | Alliance Semiconductor Corporation |
| ALSI | Advantage Learning Systems, Inc. (delisted) |
| ALSK | Alaska Communications Systems Group |
| ALST | Allstar Inns, Inc. |
| ALTI | Altair Nanotechnologies, Inc. |
| ALTIF | Altair International, Inc. (delisted) |
| ALTM | Alternative Postal Delivery (formerly Alternate Marketing Networks) |
| ALTN | Alteon, Inc. |
| ALTR | Altera Corporation |
| ALTS | Altris Software, Inc. |
| ALTSE | Altris Software, Inc. |
| ALTX | Altex Industries, Inc. |
| ALVEF | Alexa Ventures, Inc. |
| ALXN | Alexion Pharmaceuticals, Inc. |