Fidelity cuts fees to as low as 0% as mutual fund companies battle for investors

The price war among mutual fund companies is hitting a new frontier -- to the further benefit of investors: Fidelity Investments says it will soon offer a pair of mutual funds that charge zero in expenses.

That's not a typo. The new 0% index funds are part of a suite of changes Fidelity is making to lower expenses and make investing easier, even for investors with smaller amounts to put into the market.

Mutual fund companies have been battling to attract customers, who have become increasingly aware of how much high fees can limit returns.

The two zero-fee Fidelity index funds will be available Friday. One will cover the U.S. stock market, and the other will follow the international stock market. These kinds of funds often form the centerpiece of a retirement portfolio, along with bond funds.