| 3Spine, Inc. | |
| 3Squared Technology Group | |
| 3T Pro, Inc. | Texas |
| 3TBiosciences, Inc. | California |
| 3Tech Group | Texas |
| 3techagency | |
| 3thirds, Inc. | |
| 3twenty9 Design | |
| 3Victors | Texas |
| 3W Studios | Florida |
| 3wCommunications, Inc. | |
| 3Wire Systems, Inc. | California |
| 3wPlanet Studio | California |
| 3z.net | Kentucky |
| 4 Best Business Corporation | Florida |
| 4 Elbows, LLC | New Jersey |
| 4 Less Communications, Inc. | California |
| 4 Sight Design | Florida |
| 4 Star Electronics, Inc. | California |
| 4 Step Studio, Inc. | |
| 4 Walls, Inc. | |
| 4 Way Technologies | California |
| 400 School, Inc. | Missouri |
| 401GO | Utah |
| 405 Ads Online Marketing | |
| 405 Ads, Inc. | California |
| 405 Group | California |
| 406 Ventures | Massachusetts |
| 40Billion.com, Inc. | Georgia |
| 410 Labs | Maryland |
| 410 Medical | North Carolina |
| 411 Locals | |
| 412 Venture Fund, L.P. | Pennsylvania |
| 41Labs | Wyoming |
| 42 Technologies, Inc. | California |
| 42, Inc. | California |
| 42.Ventures | Utah |
| 420 Web Pros | California |
| 425 Consulting Group, LLC | |
| 428 Designs, Inc. | |
| 42Chat | Utah |
| 42connect | |
| 42DM | New Jersey |
| 42U.com | Colorado |
| 42uHosting, LLC | Wyoming |
| 43North | New York |
| 44 Degrees North, LLC | Vermont |
| 44 Interactive | South Dakota |
| 4490 Ventures | Wisconsin |
| 44i Digital | |