I estimate a single factor model of Swiss exchange rates during World War I for five of the primary belligerents: Britain, France, Italy, Germany, and Austria-Hungary. At the outbreak of the war these nations suspended convertibility of their currencies into gold with the promise that after the...

All costs generated by broker’s commission are included in portfolio optimization. The value of indicated broker’s commission is given as a constant point of some simple iteration process. The switching process is described as a closed transportation problem. It is proved that for a fixed...