Compare Online Brokers; How We Scored Discount Brokers. To find the best online discount brokers for stock trading, we considered all the possible scenarios. Whether the trades involved 100 shares or 5,000 shares, $5,000 in equity or $1 million in equity, margin or no margin, we assessed it all. Investors searching for a new broker should compare online brokers to find the best solution that suits their needs. Below we have a breakdown of nine stock brokers sorted by overall rating: TD Ameritrade, ETRADE, Fidelity, Charles Schwab, Merrill Edge, Ally Invest, TradeStation, Interactive Brokers, and Just2Trade. Firstrade is a discount broker that provides self-directed investors with brokerage services, and does not make recommendations or offer investment, financial, legal or tax advice. Options trading involves risk and is not suitable for all investors. Options trading privileges are subject to Firstrade review and approval.