Another weird thing I noticed is that sometimes my account Net Liquidity and daily P&L will go up, but excess liquidity will go down.
I imagine that this is because I hold some long positions that require 100% maintenance margin, and as the price for those stocks increases, so does the maintenance requirement.
I am really not sure about this though.
Actually that does not make any sense, it is probably due to the value of some other positions (that don't drive the P&L) moving against me.
I wish there was a way to look up maintenance margin for individual positions, so it would be easier to track what is going on.