Because C2's Model Account lets you trade many kinds of instruments from one margin pool (stocks, options, futures, forex), we display margin availability a bit different than what you might expect. We show "Buy Power" which is a good stand-in for "margin available" but not exactly the same thing.
What you need to know is that when you buy a stock above price $5, your "Buy Power" decreases by only half the nominal value of the stock position. This simulates buying the remainder "on margin."
To take an example:
If you start with $50,000 in cash, and then you buy 1000 shares of stock XYZ for $40 per share, your "Buy Power" will show: $30,000.
1,000 shares x $40 share = 40,000 ... but your BP decreases by only half, which is $20,000.
This system allows you to also make futures and forex trades out of the same "margin pool" by applying those instruments' specific margin rules to the Buy Power pool you have available.
A bit unusual, but it allows the C2 Platform to work with multiple instrument classes, and allows strategy-buyers to make apples-to-apples comparisons between strategies and their margin requirements.