In the finance field, it is quite common to express some measures in relation to some grouping criteria. Some groupings can be temporal (year, month, etc.) and others like greography, asset class (e.g. a financial product), strategy (used in trading), and others.
Which one is the most appropriate preposition to apply in this kind of expression ?
- "VaR per asset" or "VaR by asset"
- "P&L per strategy" or "P&L by strategy".
Is there any well defined rule behind the most appropriate use ?