The battle to offer retail ETF investors more cost-free choices continues to heat up.

Just last week, Fidelity took the wraps off its revised and enlarged commission-free ETF offerings. This increase now gives retail investors over 500 choices.

Fidelity already offered commission-free trading on its own ETFs and on iShares products through a deal with BlackRock.

According to Fidelity, the expansion to its ETF family of funds adds almost 150 ETFs from 11 different ETF issuers: American Century, First Trust, Franklin Templeton, Goldman Sachs Asset Management, Invesco, Janus Henderson, John Hancock Investments, J.P. Morgan Asset Management, Legg Mason Global Asset Management, PIMCO and State Street Global Advisors SPDR ETFs.

A full list of the ETFs on which Fidelity offers commission-free trading is available on its website.

For comparison, Charles Schwab and TD Ameritrade each currently also offer more than 500 commission-free ETFs on their platforms. However, Vanguard remains the champion of the freebie – offering about 1,800 commission-free ETFs on its platform.