 Complete the following phrase:  Margin lending became popular in the late 1800s as a means to fice railroads. In the 1920s, margin requirements were loose. In other words, brokers required investors to put in very little of their own money, whereas today, the Federal Reserves margin requirement under Regulation T limits debt to 50 percent. During the 1920s leverage rates of up to 90 percent debt were not uncommon. When the stock market started to contract, many individuals received margin calls. They had to deliver more money to their brokers or their shares would be sold. Since many individuals did not have the equity to cover their margin positions, their shares were sold, causing further market declines and further margin calls. This was one of the major contributing factors which led to the 