What does "at south of $100 million" mean?

From this article:

Judge Alsup did take the unusual step of appointing his own damages expert. That independent expert valued the patent case at south of $5 million, and valued the copyright case at south of $100 million.

It sounds like it means either:

the minimum value is $100 million

or:

the maximum value is $100 million

Solution 1:

"South" here means less than, a meaning derived from the fact that south is down on most maps, and that smaller numbers are often conceptualized as physically "lower" than larger ones.

Therefore, to select one of your alternatives, the maximum value is $100 million.

(Although this usage of south feels colloquial, it isn't particularly common - I wouldn't advise using it either in everyday speech or in formal writing. The author is presumably using it here because he's aiming for a casual, light-feeling journalistic style.)

Solution 2:

It means "a little bit less than". So "south of $100 million" might turn out to be, say, $96 million or $98 million.