Fidelity Investments is stepping up its rivalry with Vanguard Group by launching five new index mutual funds with expense ratios it says are lower than the equivalent products at its competitor.

Fidelity, which has $2.8 trillion under management, on Tuesday announced the addition of four index funds with expense ratios of 0.05% that invest in either mid-cap or small-cap growth or value stocks, as well as a municipal bond vehicle charging 0.07%. Expense ratios on equivalent funds at Vanguard range from 0.06% to 0.19% depending on the class of investor, according to data compiled by Bloomberg.

Fidelity has been engaging in a price war with competitors as investors flock to the cheapest products. Last year, it offered the first zero-fee index mutual funds. Across U.S. stock and bond mutual funds and ETFs, passively managed products attracted net deposits of about $252.9 billion in the first half of this year, while the active side of the industry saw $28.5 billion flee, according to data from research firm Morningstar Inc.

In addition to the new mutual funds, Fidelity’s 53 existing stock and bond index funds and 11 sector exchange-traded funds carry lower expense ratios than Vanguard, the Boston-based firm said in a news release. Fidelity last month cut fees on target-date mutual funds and expanded its commission-free ETF platform.

Fidelity has almost $500 billion in assets in index mutual funds.

In an interview with Bloomberg Markets magazine in November, Chief Executive Officer Abigail Johnson said offering a series of zero-fee funds and eliminating investment minimums were aimed at allowing the firm to “find other ways for people to give us a try.”