| S2 Games | video game developer | Kalamazoo | 2003 |
| Saber Interactive | video game developer | Fort Lauderdale, Minsk, Sundsvall, Porto, Millburn, Community of Madrid, Saint Petersburg, Florida | 2001 |
| SAE International | engineering society, regulatory college, standards organization, business, company, academic publisher | Warrendale | 1905 |
| Safeway | supermarket chain, business, enterprise, public company | Pleasanton | 1915 |
| Sahara Las Vegas | skyscraper, hotel, casino hotel, music venue | — | 1952 |
| Saint Anselm College | private not-for-profit educational institution, liberal arts college in the United States | Manchester | 1889 |
| Sam's Club | supermarket chain | Bentonville | 1983 |
| San Diego FC | association football club, business | San Diego | May 18, 2023 |
| San Francisco Museum of Modern Art | nonprofit organization, art museum, publishing house, museum, museum of modern art | San Francisco | 1935 |
| San Francisco Opera | nonprofit organization, opera company | San Francisco | 1923 |
| San Francisco State University | public educational institution of the United States, university | — | 1899 |
| Sandisk | technology company, brand, business, enterprise | Milpitas | June 1, 1988 |
| Santa Monica Studio | video game developer | Playa Vista | 1999 |
| Schomburg Center for Research in Black Culture | library branch, creative residency, research library, public library, library building | — | 1925 |
| School of Visual Arts | private for-profit educational institution, art academy, university | New York City | 1947 |
| Schwinn Bicycle Company | business | Chicago | 1895 |
| Scribd | online service, organization, business | San Francisco | March 2006 |
| Sealy Corporation | business, enterprise, public company | Trinity | 1881 |
| Sean Cody | pornography website, pornographic film studio | United States | 2001 |
| Sears | business, public company | Hoffman Estates | 1892 |
| Sears Holdings Corporation | business, enterprise, public company | Hoffman Estates | 2005 |
| Seattle Computer Products | business | Seattle | 1979 |
| Seattle's Best Coffee | business | Seattle | 1991 |
| SeaWorld | business, chain | Orlando | March 21, 1964 |
| Selig Polyscope Company | film production company | Los Angeles | 1896 |
| Selznick International Pictures | film production company, film studio | Los Angeles | 1935 |
| Semrush | brand, business, public company | Boston | August 3, 2008 |
| Sesame Workshop | production company, nonprofit organization | 1 Lincoln Plaza, New York City | May 20, 1968 |
| Shen Yun | nonprofit organization, business | Deerpark | 2006 |
| Sheraton Hotels and Resorts | hotel chain, business | White Plains | 1937 |
| Sherwin-Williams | business, enterprise, public company | Cleveland | 1866 |
| Shiny Entertainment | video game developer, business | Laguna Beach, Newport Beach | 1993 |
| Shippensburg University of Pennsylvania | public educational institution of the United States, university | — | 1871 |
| ShondaLand | television production company | Los Angeles | 2005 |
| Showtime | business | New York City | 1983 |
| Shrine Auditorium and Expo Hall | auditorium, function hall, theatre building, movie theater | — | 1925 |
| Shuttle America | airline | Indianapolis | 1998 |
| Sierra Nevada Brewing Company | brewery | Chico | 1980 |
| Sikorsky Aircraft Corporation | aerospace manufacturer | Stratford, Connecticut | 1923 |
| Silicon Laboratories | business, public company | Austin | 1996 |
| Silver Pictures | film production company, business | Los Angeles | 1980 |
| Silvergate Capital | savings and loan association, bank, business, public company | La Jolla | 1988 |
| Similarweb | website, business, public company | Givatayim | 2007 |
| Simon & Schuster | book publisher, publishing house | New York City | 1924 |
| Sinclair Broadcast Group | business, enterprise, public company | Hunt Valley, Cockeysville, Union Valley | 1971 |
| Sir-Tech | video game developer | Ogdensburg | 1979 |
| Sirius Satellite Radio | former entity, business, company | New York City | May 17, 1990 |
| Six Flags | business, enterprise, public company | Arlington | 1961 |
| Six Flags | business, enterprise, public company | Charlotte | July 1, 2024 |
| Six Flags Magic Mountain | amusement park | — | 1971 |
| Skechers | business, enterprise, public company | Manhattan Beach | 1992 |
| Sketchfab | 3D printing marketplace, website, business | New York City | 2012 |
| Skydance Media | production company, business | Hollywood | 2006 |
| Slack Technologies | business, public company | San Francisco | 2009 |
| SLB | business, enterprise, public company, oilfield service company | Houston | 1926 |
| Slots-A-Fun Casino | casino | — | August 5, 1971 |
| Smashburger | restaurant chain | Denver | 2007 |
| Snap-on | business, public company | Kenosha | 1920 |
| Snowflake Inc. | software company, organization, business, software, public company | San Mateo | 2012 |
| Society for Industrial and Applied Mathematics | mathematical society, nonprofit organization, publishing house, source of information, learned society | University City | 1951 |
| Soka University of America | private not-for-profit educational institution, higher education institution, school | Aliso Viejo | 2001 |
| SolarCity | organization, business, subsidiary company, public company | San Mateo, California | 2006 |
| Sonoma State University | public educational institution of the United States, university, census-designated place in the United States | — | 1960 |
| Sons of the American Revolution | research library, nonprofit organization, patriotic society, museum, men's organization, charitable organization, lineage society | Louisville | April 30, 1889 |
| Sony Corporation of America | business, subsidiary company | 550 Madison Avenue, New York City | 1960 |
| Sony Entertainment | entertainment company, business | New York City | 2012 |
| Sony Imagesoft | business | Los Angeles | 1989 |
| Sony Music | major label, record company, business | New York City | January 1, 2009 |
| Sony Pictures Animation | animation studio | Culver City | 2002 |
| Sony Pictures Classics | film production company, film distributor | New York City, Los Angeles | January 1992 |
| Sony Pictures Motion Picture Group | business | Culver City | 1998 |
| SoundHound | music recognition software, enterprise, public company | Santa Clara | September 2005 |
| South Dakota State University | public educational institution of the United States, land-grant university, public research university, sun grant institution | — | 1881 |
| Southeastern Louisiana University | public educational institution of the United States, university | — | 1925 |
| Southern California Institute of Architecture | architecture school, private not-for-profit educational institution, university | — | 1972 |
| Southern Illinois University Carbondale | public educational institution of the United States, public university | — | 1869 |
| Soylent | brand, business, drink mix, meal replacement | Los Angeles | 2013 |
| SpaceX | launch service provider, business, public company, aerospace manufacturer | Starbase | March 14, 2002 |
| Spansion | business, enterprise, public company | Sunnyvale | 2003 |
| Specialized Bicycle Components | bicycle manufacturer, business, enterprise | Morgan Hill | 1974 |
| Spector | business | Saugerties | 1976 |
| Spectrum Brands | business, enterprise, public company | Middleton | 1906 |
| Sports Reference | business | Philadelphia | December 3, 2007 |
| Springfield Armory | business | Geneseo | 1974 |
| Sprint Corporation | mobile network operator, business, enterprise, public company | Overland Park | 1899 |
| Squarespace | commercial organization, public company | New York City | 2003 |
| St. Edward's University | private not-for-profit educational institution, university | — | 1873 |
| St. Thomas University | private not-for-profit educational institution, university, open-access publisher | — | 1961 |
| Standard Oil | holding company, business, enterprise | Ohio, Cleveland, New York City | 1890 |
| Stanford University | research university, private not-for-profit educational institution, open-access publisher, private university | Stanford | 1885 |
| Stanley Black & Decker | business, public company | New Britain | 1843 |
| Staples Inc. | business, retail chain, enterprise, public company | Framingham | 1986 |
| Starbucks | café chain | Seattle | March 30, 1971 |
| Starwood | business, enterprise, public company | White Plains | 1930 |
| State Farm Insurance | business, car insurance company, life insurance company, property insurance company | Bloomington | 1922 |
| State University of New York at Albany | public educational institution of the United States, public university | Albany | 1844 |
| State University of New York at Purchase | public educational institution of the United States, university | — | 1967 |
| Steak 'n Shake | restaurant chain, business, enterprise | Indianapolis | 1934 |
| Steinway Musical Instruments | business, musical instrument manufacturing company, enterprise | Waltham | 1995 |
| Sterling Memorial Library | academic library, library building | — | 1930 |
| Sterling Trucks | truck manufacturer, commercial vehicle manufacturer | Redford | 1997 |
| Stevens Institute of Technology | private not-for-profit educational institution, university | — | 1870 |
| Strand Bookstore | book vendor | — | 1927 |
| Stratfor | think tank, business, secret service | Austin | 1996 |
| Stratolaunch Systems | business, enterprise | Montgomery, Seattle | 2011 |
| Stripe | payment processor, business | San Francisco, South San Francisco | 2010 |
| Studebaker | business, automobile manufacturer | South Bend | 1852 |
| Stuyvesant High School | school, specialized high school in New York City, high school | New York City | 1904 |
| STX Entertainment | film production company, film distributor, public company | Burbank | March 10, 2014 |
| Stüssy, Inc. | business, enterprise | Irvine | 1980 |
| Sullivan & Cromwell | law firm | New York City | 1879 |
| Sumisho Air Lease | business, enterprise, public company | Los Angeles | 2010 |
| Sunkist Growers | business, enterprise | Los Angeles | August 29, 1893 |
| Supergiant Games | video game publisher, video game developer | San Jose | 2009 |
| 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 |
| Synopsys | business, enterprise, public company | Mountain View | 1986 |
| Sysco | business, public company | Houston | 1969 |
| System76 | brand, business | Denver | November 7, 2005 |