==Modern Stock Markets==
Throughout the late 19th century and early 20th century, stock markets became more directly linked with the major companies in countries, which were often rail, coal, and steel industries. Financing came from stock exchanges and company success began to depend on increasing growth of stock values. This increasingly also made the economy vulnerable to panic selling and there was no regulation to stop runaway selling. The Black Thursday and Black Tuesday crashes of October 24 and 29, 1929 are widely seen as the triggers for the Great Depression of the 1930s. These were examples of panic selling that greatly reduced financial flows to major companies. To prevent panics such as these major crashes, new rules were introduced in the 1930s and the creation of the U.S. Securities and Exchange Commission in 1934 helped regulate financial markets around the country, in particular the New York Stock Exchange. The Great Depression also demonstrated that the global economy, and not just the economy of the United States, began to become more linked so that panic selling in one stock market began to affect other stock markets and economies .