Will IB double the portfolio margin requirement at 3:50PM?

[GoogTgt]

I currently have RegT with IB. It seems to apply 50% RegT margin at 3:50pm ET and liquidate if I am below that. This was a surprise for me since it kept saying 25% initial margin through out the day.

Now I am thinking of switching to portfolio margin. Does IB suddenly double the portfolio margin requirement at 3:50pm as well like regT?

 

[1245]

They did that to you to stop margin calls. Pm is the same at night as DT. Reg-t is not.