> Trading is only zero sum at an instant in time and space. Moving or holding commodities can change the sum of the trade.

Trading between financial participants is, cetiris paribus, always zero sum. Irrespective of the timeline.

Buyer's gains are the seller's opportunity cost; buyer's losses were avoided by the seller. (Paribus violation is when parties have different funding costs.)

Moving commodities around isn't trading per se; it's logistics. Again, value adding.

>Trading between financial participants is, cetiris paribus, always zero sum.

Only if you consider the trade in the quantity of the goods traded, and not in a prevailing unit of accounting.

> Only if you consider the trade in the quantity of the goods traded, and not in a prevailing unit of accounting

Nope, this is microeconomics. If you and I have the same funding costs and we trade a commodity derivative, any gain you have is a gain I gave up. Any loss you have is one I avoided.

This is true irrespective of the unit of account of point in time at which one measures it; it's an identity. The only

You are carefully defining the word “trading” to meet a narrow academic category which excludes many cases normal people consider integral to “trading”.

Someone who buys wheat, holds it and sells it the next day is definitely not “trading”, he merely engages in a series of discrete trades? Daft.