Aggregate of Multiple columns IF a condition is met

I have a formula that gets the overall median of four ranges:
Aggregate(12,6,A2:A1000,B2:B1000,C2:C1000,D2:D1000).
I'm trying to modify this formula to get the aggregate median for ONLY the values below zero.
Note that some of the cells will be empty.
Any suggestions?

I simplified things too much in my original post. My columns are not adjacent to each other. A better example would be:
Aggregate(12,6,a2:A1000,G2:G1000, R2:R1000,Z2:Z1000)
There is other data between these columns, and some cells are blank.

other option , pls try

Formula:

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Thanks.
I used:
=LET(t,HSTACK(A2:A1000,G2:G1000,R2:R1000,Z2:Z1000),MEDIAN(IF(t<0,t)))
and it appears to work. I'll have to figure out how it works.

I've been using Excel (and VBA) for about 35 years and know a lot, but there are still things I don't know!