The Hitchhiker's Guide to PM Probabilities

I've uploaded my handy excel spreadsheet that works out what the price of PM.National would be if the prices in the underlying markets are correct and if my bold simplifying assumptions aren't too bold. Though the spreadsheet contains much that is apocryphal, or at least wildly inaccurate, if the calculations show a big gap between the calculated price and the current market price, there's likely an arbitrage opportunity playing around somewhere in the prices. Either in the prices in the underlying markets, or in the PM markets themselves.

Be warned: the file is 24 MB, mostly because I cribbed somebody else's Sainte-Lague spreadsheet and because my Excel coding skills are padawan-level at best, I copied those sheets four times over to work out the seat shares in four relevant cases: Act returns (or doesn't) and NZ First returns (or doesn't).

Happy trading!