Final answer:
Black Thursday refers to October 24, 1929, the day when the stock market crash began and marked the start of the Great Depression.
Step-by-step explanation:
October 24, 1929 became known as Black Thursday because it was the day when the stock market crash began. The Dow Jones Industrial Average had fallen nearly 5% the day before, and on Black Thursday, the market took another sharp downward turn. Financial losses were in the billions of dollars, and small investors were wiped out. This event marked the start of the Great Depression, a period of severe economic decline in the United States. Prior to these events, signs of an overextended market were apparent, with banks providing too many loans for stock purchases and speculation running rampant, despite warnings from financial experts. These practices, combined with failing efforts by the Federal Reserve to control the situation and the misguided optimism of investors, set the stage for disaster.