Let's say you have a $10,000 portfolio. You want to buy stock A which trades at $100 and short stock B which also trades at $100, at 150%/50% respectively.
So you buy 150 shares of A and sell 50 shares of B.
Let's assume for the moment that maintenance margin requirements are 30% on both stocks. So right now your maintenance requirement is $6,000 (right?)
Can somebody help me understand what happens to your maintenance margin requirements if both stocks A and B fall in price by $X? Say they both fall from $100 to $50.