Hollywood was one of several players in the world film market until the outbreak of the First World War, when indigenous film production in Europe came almost to a standstill. Rushing to fill the void, Hollywood underwent a period of rapid expansion, and film-making became a major industry. Producers sought market security by acquiring large chains of theatres; large chains of theatres sought a steady supply of films by acquiring studios. To finance these mergers, companies turned to Wall Street. The advent of the talkies in 1926 created even closer bonds with banking interests. Only the strongest film companies had the financial resources or connections to make the conversion to sound, with the result that by 1930 Hollywood emerged as a virtual oligopoly consisting of eight companies, most of which continue to dominate the business to this day.