Banks will list all of the different maturities of their certificates with the current yields, so you can pick the CD with the highest yield and maturity appropriate for your needs.

Banks will also automatically update the value of your securities portfolio, usually every night after the stock market has closed. In addition, the bank will keep track of reinvesting stock dividends and mutual fund capital gains distributions and will adjust for stock splits and bond redemptions. The bank also should keep track of your cost basis so that you can calculate your capital gains liability when you sell an investment. All of these recordkeeping chores would be a tremendous burden for you to track on your own.

Ever since the banking industry was fully deregulated in the early 1980s, banks and savings and loans have been free to pay as much as they choose on checking and savings accounts. A bank that wants to generate a large amount of deposits to make loans will offer higher interest rates than a bank that does not anticipate much loan demand.

Though there are variations from bank to bank, the yields you earn on your cash are affected more by the general movement in interest rates than by individual banks themselves. If inflation is high and rising and the Federal Reserve pushes up interest rates to try to cool off the economy, cash instruments will pay rates from 8 percent to as much as 20 percent, as they did in the early 1980s. Under these circumstances, which persisted in the 1990s and 2000s, yields on cash can fall dramatically to as low as 2 percent.