S.I. Newhouse Jr., who as the owner of The New Yorker, Vogue, Vanity Fair, Architectural Digest and other magazines wielded vast influence over American culture, fashion and social taste, died on Sunday October 1 2017 at his home in New York. He was 89. Mr. Newhouse, known as Si, and his younger brother, Donald, inherited an impressive publishing empire from their father, Solomon I. (“Sam”) Newhouse, and built it into one of the largest privately held fortunes in the United States, with estimates of the family wealth running over $12 billion at the turn of the 21st century. While Donald led the more profitable newspaper and cable television operations, Si took charge of the more glamorous magazine division. Mr. Newhouse hired some of the most charismatic magazine editors of the late 20th century, among them Tina Brown at Vanity Fair and Diana Vreeland and Anna Wintour at Vogue, and encouraged them to behave like the celebrities they extolled in his publications.T wo Hollywood movies, “The Devil Wears Prada” and “How to Lose Friends and Alienate People,” were made based on accounts of life at two of Mr. Newhouse’s flagship publications, Vogue and Vanity Fair. Because his publications were privately held, he did not disclose their finances. But according to a 1996 Wall Street Journal article, Condé Nast lost up to $20 million in 1994 as nine of its 14 publications ran deficits. Unprofitable magazines like Mademoiselle and Gourmet were shut down. Random House was sold to Bertelsmann, the German publishing giant, for $1.4 billion in 1998, two decades after Mr. Newhouse had paid $60 million for it. During the period of retrenching, Mr. Newhouse sold most of his art collection and moved out of his large townhouse into a smaller apartment. While his publishing ventures were in no danger of foundering, he dedicated himself to making certain that they would prosper after his retirement. Mr. Newhouse began to step back from the business in the late 2000s. Solomon Isidore Newhouse Jr. was born on Nov. 8, 1927, and was known from childhood as Samuel. His father, Sam Newhouse, the son of an impoverished Russian immigrant, was a lawyer who in 1922 invested his earnings in a failing newspaper, The Staten Island Advance. Under the name Advance Publications, Sam Newhouse and his brothers slowly built up one of the largest newspaper chains in the country, including, among more than a score of others, The Long Island Daily Press, The Star-Ledger, The Cleveland Plain-Dealer, and The St. Louis Globe-Democrat. To please his wife, Mitzi, who loved Vogue, Sam Newhouse in 1959 bought Condé Nast, a company that published the magazine along with Glamour, House & Garden and Young Brides. Si Newhouse, by his own admission, had been at loose ends. He dropped out of Syracuse University and worked halfheartedly at Newhouse headquarters. His first marriage, to Jane Franke, with whom he had three children, Sam, Wynn and Pamela, ended in divorce in 1959 after eight years. Mr. Newhouse is survived by his wife, Victoria, his brother, Donald, two children, Sam and Pamela Mensch, five grandchildren and three great-grandchildren. His son Wynn died in 2010.