| Sigmetrix | Texas |
| SIGMOVIR Biosystems, Inc. | |
| Sigmund Software | Connecticut |
| Sign In Enterprise | |
| Signa Marketing | |
| Signa Tech Solutions, LLC | Wisconsin |
| SignaBlok, Inc. | Massachusetts |
| signageOS | California |
| Signal & Power Delivery Systems, Inc. | California |
| Signal Antenna Systems, Inc. | California |
| Signal Cable | New York |
| Signal Communications Systems | California |
| Signal Communications, Inc. | Virginia |
| Signal Communications, LLC | Florida |
| Signal Design, Inc. | North Carolina |
| Signal Electronics, Inc. | Texas |
| Signal Engineering, Inc. | California |
| Signal Genesys | Florida |
| Signal Hound | Washington |
| Signal Intelligence | California |
| Signal Mountain Networks, LLC | |
| Signal Peak Ventures | Utah |
| Signal Point | Georgia |
| Signal Sciences | California |
| Signal Theory | |
| Signal21, Inc. | |
| SignalCore, Inc. | |
| SignalFire | California |
| Signalfire, LLC | Wisconsin |
| Signals Analytics | New York |
| Signals Defense | |
| Signalway Antibody, LLC | Maryland |
| SignalWire, Inc. | California |
| Signamax, Inc. | Florida |
| Signant Health | Pennsylvania |
| SignaPay | Texas |
| Signatec, Inc. | Illinois |
| Signati Medical | Rhode Island |
| Signature Biologics, LLC | Texas |
| Signature Devices, Inc. | Wyoming |
| Signature Logos | |
| Signature W Studio | |
| SignatureConfirm.com | Texas |
| Signaturely | California |
| SignChannel | Pennsylvania |
| Signeasy | Texas |
| Signerlabs, Inc. | |
| Signet Healthcare Partners | |
| Signetic | Washington |
| SignGlasses | Utah |