Margin

When you buy a stock on margin, you pay for part of the purchase and borrow the rest from your brokerage firm. For example, you may buy $5,000 worth of stock in a margin account by paying for $2,500 and borrowing $2,500 from your firm. To learn how margin trading works, the upsides and downsides, and the risks involved, read Margin: Borrowing Money To Pay for Stocks.