Short answers, pulled from the story.
Jack L. Warner was a Canadian-born American film executive who served as president and the driving force behind Warner Bros. Studios in Burbank, California. His career spanned over 55 years, surpassing that of any other pioneering Hollywood studio mogul. He is known for helping introduce talking pictures with The Jazz Singer in 1927 and for producing socially driven films throughout the studio's golden era.
Jack L. Warner was born Jacob Warner on the 2nd of August 1892, in London, Ontario, Canada, to Polish-Jewish immigrant parents. He spent much of his youth in Youngstown, Ohio, after his family relocated there in 1896 to join his eldest brother Harry, who had opened a shoe repair shop in the steel town.
In July 1956, Jack, Harry, and Albert Warner announced they were putting the studio up for sale. Jack secretly organized a syndicate to purchase controlling interest before his brothers realized what was happening. By the time Harry and Albert understood the situation, it was too late; Jack, now the company's largest stockholder, appointed himself president. Harry never spoke to Jack again.
Jack Warner worked with his brother Sam to procure the Vitaphone sound technology that made The Jazz Singer possible. Sam died of pneumonia the day before the film's premiere, and Jack became sole head of production. From an investment of $500,000, the film yielded $3 million in profits and established Warner Bros. as a major studio.
Jack Warner appeared as a friendly witness before the HUAC on the 27th of October 1947, voluntarily naming a dozen screenwriters he had dismissed for suspected communist sympathies. He believed communists were responsible for a month-long studio strike in the fall of 1946. Those named included Ring Lardner Jr., Dalton Trumbo, Alvah Bessie, and others, and the testimony effectively destroyed their careers.
On the 14th of November 1966, Warner sold a substantial portion of his 1.6 million shares of studio stock to Seven Arts Productions. After capital gains taxes, the sale yielded approximately $24 million. He had produced the film adaptation of Camelot shortly before completing the transaction and officially retired from the studio in 1969.