So for quite a long time now, I have been using the "Non-margin Buying Power" (on Fidelity) or "Non-Marginable Purchasing Power" (on Etrade) to decide how much margin was left for doing BPS. And I always try to keep it at a high level. Last week when the SP was pretty low I was checking Fidelity and while my Non-Margin BP was about $350K, I noticed in the margin balance details page that my "House Surplus" was down to about $70K. And this got me quite concerned as it is hidden away from normal view.
To fix some of this, I did a few BPS to CC conversions this morning and freed up another $20K of margin.
Its unclear to me how Fidelity calculates this House Surplus, wondering if people have got margin called on that?
Also, I can't find any similar number on Etrade. Do they have something like that I need to be concerned about?