It depends. I worked on a trading platform that >1M LOC. The overall complexity was lower than another quantitative modelling engine that only had couple of ten

It depends. I worked on a trading platform that >1M LOC. The overall complexity was lower than another quantitative modelling engine that only had couple of tens of thousands LOC. Complexity, work and LOC are correlated, but the correlation is not 1. In the case of the former system, 95% of the code was connectivity, GUI, persistence, etc., the actual business logic was maybe 5%. And I'm not even talking about stuff written in kdb/q, where I produced maybe 500 LOC in a month. :)