The amount of margin a trader has available to trade with.

This is account balance minus margin used on open positions.

This is a measure of price performance vs a benchmark.

If a trader makes 10% per annum and the index makes 7% the trader has an alpha of 3%.

A term used by brokers to describe a rapidly moving or thinly traded market.

Depending on the terms and conditions, this allows brokers to examine and possibly change trades placed during these conditions.