| Springfield College | private not-for-profit educational institution | Springfield | 1885 |
| Sprint Corporation | mobile network operator, business, enterprise, public company | Overland Park | 1899 |
| Sprouts Farmers Market | supermarket chain, business, health food store chain, public company | Phoenix | July 2002 |
| Spyglass Media Group | film production company | Los Angeles | 1998 |
| SRI International | nonprofit organization, research institute, business | Menlo Park | 1946 |
| St. Lawrence University | private not-for-profit educational institution, liberal arts college in the United States, private university | Canton | 1856 |
| Stage 6 Films | business | Culver City | 2007 |
| Standard Oil of Ohio | business, gas station chain | Cleveland | 1911 |
| Stanford University Press | book publisher, publishing house, university press | Redwood City | 1892 |
| Stanley Motor Carriage Company | automobile manufacturer | Newton | 1902 |
| Staples Inc. | business, retail chain, enterprise, public company | Framingham | 1986 |
| Starbucks | café chain | Seattle | March 30, 1971 |
| Stellantis North America | business, enterprise, automobile manufacturer | Chrysler Headquarters and Technology Center | April 28, 2009 |
| Stony Brook University | research university, public educational institution of the United States, public university | Stony Brook University | September 16, 1957 |
| Strand Bookstore | book vendor | — | 1927 |
| Strategic Simulations | video game publisher, video game developer, business, enterprise | Sunnyvale | 1979 |
| Strategy | software company, business, public company | Tysons | 1989 |
| Stratton Oakmont | brokerage firm | Lake Success | 1988 |
| Studebaker | business, automobile manufacturer | South Bend | 1852 |
| Studebaker-Packard Corporation | automobile manufacturer | Detroit | 1954 |
| StumbleUpon | website, business | San Francisco | 2001 |
| STX Entertainment | film production company, film distributor, public company | Burbank | March 10, 2014 |
| Substack | website, publishing platform, business, podcast hosting service, enterprise, service | — | November 29, 2017 |
| Sucker Punch Productions | video game developer | Bellevue | October 1997 |
| Suffolk University | private not-for-profit educational institution, private university | Boston | 1906 |
| SugarCRM | free software, business | Cupertino | 2004 |
| Summit Entertainment | film production company | Universal City | July 26, 1991 |
| Sun Microsystems | software company, academic spin-off, business, public company | Santa Clara | February 24, 1982 |
| Supreme | apparel brand, business, enterprise | New York City | April 1994 |
| SureFire | business, enterprise | Fountain Valley | 1979 |
| SurveyMonkey | customer experience management, software as a service, service on Internet, trademark, enterprise feedback management, online survey service, market research and public opinion polling, business, Customer experience systems, public company, market research | San Mateo | 1999 |
| Swarthmore College | liberal arts college, private not-for-profit educational institution | — | 1864 |
| Swift Engineering | business, enterprise, aerospace manufacturer | San Clemente | 1983 |
| Sylvania Electric Products | organization, enterprise | — | 1942 |
| T. Rowe Price | business, enterprise, public company | Baltimore | 1937 |
| Tablet | podcast production company, online magazine | Manhattan | June 2009 |
| Tandem Computers | manufacturing company, business | Cupertino | 1974 |
| Tarleton State University | public educational institution of the United States, university | — | 1896 |
| TASCAM | business | Tokyo | 1971 |
| Taylorcraft Aircraft | aerospace manufacturer | Brownsville | 1935 |
| TaylorMade Golf Company | business | Carlsbad | 1979 |
| Tazo | business | Portland | 1994 |
| TBWA Worldwide | business | New York City | 1970 |
| TD Ameritrade | business, enterprise, public company | Omaha | 1971 |
| Teledyne Technologies | business, conglomerate, public company | Thousand Oaks | 1960 |
| Temple Hill Entertainment | film production company | Los Angeles | 2002 |
| Tennessee State University | historically black college or university, public educational institution of the United States, school, land-grant university, public university | — | 1912 |
| Tennessee Technological University | public educational institution of the United States, public university | — | 1915 |