If the stocks you already own drop in value, your equity decreases. Because your borrowing limit is tied to your equity, your buying power drops too.
Buying power is a tool for . It can amplify your gains, but in a margin account, it can also amplify your losses beyond your initial investment. Always keep an eye on your "Maintenance Margin" to ensure your buying power doesn't suddenly evaporate during a market dip. stock buying power
If you have $5,000 in your account, your buying power is $5,000. If the stocks you already own drop in