I have a portfolio full of long options with no margin. I see that the market value determined by IB for each position roughly matches the midpoint of the spread. But if I sum the market values of all positions, and add it with the free cash, it is roughly 5% less than net liquidity (as displayed at the top of the IBKR mobile app). Does anyone know of any reasons as to why this may be the case? Is the net liquidity calculated somewhat differently? This was outside US market hours, i.e like just now. Same applies to the % of market val column. It doesn't sum to 100% with the free cash accounted for.
afaik, In thinkorswim net liq assumes everything closed at instantanously available prices (e.g. bid for necessary sells, ask for necessary buys, iow worse prices than mid) and market values price at mid between bid and ask (iow better prices than bid and ask).
I did the calculations again after market opening, and this time there was no inconsistency. The total of market values seemed to match net liquidity. Practically speaking, for most options I trade, I find that I can sell or buy at the midpoint or slightly worse. There are a few that I can trade at the worst price only.