| 44° North Advertising and Design | |
| 45 Degrees North | |
| 45 RPM Software | California |
| 45/RPM | |
| 451 Degrees | California |
| 451 Research, LLC | New York |
| 45PRESS, Inc. | |
| 45th Parallel Design, LLC | |
| 465-Media.com, LLC | |
| 47 Degrees, LLC | Washington |
| 47Billion | |
| 48HoursLogo.com | Georgia |
| 49 Digital Marketing Agency | |
| 490 BioTech, Inc. | Tennessee |
| 4AllThingsWeb.com | Tennessee |
| 4Biz International, LLC | |
| 4Blind | Massachusetts |
| 4byte4 | Washington |
| 4C Medical Technologies, Inc. | Minnesota |
| 4C Pharma | |
| 4Catalyzer Corporation | Connecticut |
| 4COM, Inc. | Minnesota |
| 4Corners Creative, LLC | |
| 4D Healthware | Illinois |
| 4D Lifetec, Inc. | |
| 4D Molecular Therapeutics | |
| 4D Path, Inc. | Massachusetts |
| 4D Pipeline | |
| 4degrees Digital | |
| 4Discovery | Illinois |
| 4eGuru, Inc. | California |
| 4EVER Design Studio | Illinois |
| 4Front Technologies | California |
| 4G Capital | Maryland |
| 4G Clinical | Massachusetts |
| 4Geeks Academy, LLC | Florida |
| 4Inkjets | California |
| 4iQ.com | California |
| 4it, Inc. | Florida |
| 4M Analytics | Texas |
| 4M Consulting, LLC | Colorado |
| 4M Performance | |
| 4M Therapeutics, Inc. | |
| 4me, Inc. | California |
| 4PCTechs, Inc. | California |
| 4PointDigital | New Jersey |
| 4Pros Solutions, Inc. | New Jersey |
| 4SecureMail, LLC | Virginia |
| 4Semi Used Semiconductor Equipment | New Jersey |
| 4Service, Inc. | California |