Unlike common stocks, whose dividends and earnings fluctuate with the ups and downs of the company's business, bonds pay a fixed dollar amount of interest. If the U.S. Treasury offers a $1,000 20-year, 5 percent bond, that bond will pay $50 per year until it matures, when the principal will be repaid. Corporate bonds are less safe, but widely diversified bond portfolios have provided reasonably stable interest returns over time.