http://profitabletradingtips.com/trading-investing/stock-trading-margin-rates
Stock Trading Margin Rates
Traders will always do well to look at all costs of doing business including what margin rates they are paying. If you are posting a margin of $100,000 and borrowing to post it you will typically be paying around 9% per year. That comes out to $9,000 more that you need to make in trades before you see a profit. When a firm such as Interactive Brokers offers margin rates as low as half a percent it has to get your attention. Any cost of trading should get the serious trader’s attention. It is work to make money trading catchups, trading straddles in the recovery market, and always working to see where in the world the action will be. You don’t want to give away money needlessly when you need to work hard to earn it back.