| Sierra Telephone Company, Inc. | California |
| Sierra Telephone Systems | Nevada |
| Sierra Ventures | California |
| Sierra Workforce Solutions | California |
| Sierra-Cedar, LLC | Georgia |
| SiFive | California |
| Sifo Corporation | |
| Sift | California |
| Sift Healthcare | |
| Sift Science, Inc. | California |
| Sifter, LLC | Tennessee |
| SiftHub | |
| Siftia | |
| Siftwell Analytics, Inc. | |
| SIG Digital | |
| SiGa Systems, Inc. | |
| SIGA Technologies | New York |
| Sigao Studios, LLC | |
| Sigercon, Inc. | Texas |
| SigFig | California |
| Sight Machine | California |
| Sight Machine, Inc. | |
| Sight Sciences | California |
| Sightbox | California |
| Sightech Corporation | California |
| Sighten, Inc. | California |
| Sightglass, Inc. | |
| SightLine Applications, Inc. | Oregon |
| Sightline Climate | |
| Sightline Payments | Nevada |
| Sightline Security | Massachusetts |
| Sightly Enterprises, Inc. | New York |
| SightSpan, Inc. | North Carolina |
| SightWorks | Oregon |
| SigLens | |
| SIGMA Actuary | Tennessee |
| Sigma Computing | California |
| Sigma Data Systems, Inc. | Delaware |
| Sigma Defense Systems, LLC | Georgia |
| Sigma Genetics | |
| Sigma Infosolutions | California |
| Sigma One Group, LLC | Wisconsin |
| Sigma Partners | California |
| Sigma Pharmaceuticals, LLC | |
| Sigma Prime Ventures | Massachusetts |
| Sigma Solve, LLC | Florida |
| SigmaLabs | |
| Sigmapharm Laboratories, LLC | Pennsylvania |
| Sigmatech, Inc. | Alabama |
| Sigmaways, Inc. | |