Standard economic theory (i.e., the Heckscher-Ohlin model) provides the sharp prediction that with perfect factor mobility, gains to trade flow to the abundant factors, such as unskilled labor in developing countries. (source: a paper by economist Petia Topalova)
I am having a hard time parsing this sentence. It seems to me it should be a clause after "with perfect factor mobility". Is "gain" a noun here? And is "gains to trade" the subject of that clause? If so, why is the preposition "to" used instead of "of" or "in"? I have looked at dictionaries and found sentences that use "gain in" and "gain of" but not "gains to".