Ally bank claims to have zero-comission transaction fees accounts for trading, Robinhood does the same. Do they both actually not charge any fees/comission? My understanding was that the free fees model was only Robinhood's?
Interactive Brokers introduced IBKR LITE (no commissions) which was then followed by Schwab, Ameritrade, E*Trade and then Ally.
Be aware that free doesn't always mean best price. Robinhood makes a sizable portion of their revenue from Payment For Order Flow which is effectively routing customer orders to high-frequency traders in exchange for a fee. This can result in a delayed fill and a poorer price. Paying a few extra dollars here or there for a trade is probably meaningless to an investor but it's significant for a trader.