I am working on a financial software system that deals with crypto currencies. This system has a model called 'Currency' that describes for example 'BTC' and market for which there is a 'base' and 'quote' currency.

This system is now being expanded for other types of markets, such as bitcoin futures. These products tend to have their own symbols.

I'm wondering that if I were to refactor my system to use better naming convention, what would be the most recognizable / obvious way to describe the following concepts:

  • Currency (or other financial product)
  • Base currency (or underlying? if I got that correctly?)
  • Quote currency
  • $\begingroup$ @Emma I guess my problem is that futures aren't really currencies? Or would you still call them currencies? $\endgroup$ – Evert Feb 20 '19 at 18:16
  • $\begingroup$ @Emma thank you, those links definitely help! $\endgroup$ – Evert Feb 20 '19 at 18:37
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    $\begingroup$ A future of something is just a derivative of that same something. When you click on (for example) Btc, you should then be able to see the spot price, futures, forwards, options, and any other Btc derivatives, all in the same place. $\endgroup$ – will Feb 21 '19 at 7:13

The most universal name that any "currency (pair)", "equities" or "futures" falls under is either a product or an instrument.

In some ways I prefer product because you can have 2 exchanges allowing you to trade BTC-USD or AAPL, these are fundamentally the same fungible instrument, but these are 2 different products because they have different trading fees.

Base and quote currency are constructs specific to currency pairs. They don't exist in other markets. A generalization of this is a spread, where you'd simply call them leg1 or leg2 and have some notation for quantities in either leg. This generalizes to currency pairs since for example, the constituent legs of EUR/USD are EUR and USD respectively, and your quantities in leg1 and leg2 are +1 and -1.13 respectively for an exchange rate of 1.13.

See also my answer here which may be relevant.

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    $\begingroup$ You can extend the concept to other markets, you could say that for apple stock, apple is the base currency and usd is the quote currency. $\endgroup$ – will Feb 21 '19 at 7:15

I like asset. Its price (rate) would then be quoted in terms of a numeraire. In FX markets, EURUSD rate represents the number of shares (units) of numeraire USD needed to buy one share (unit) of asset EUR (note the asset goes first). In equity markets, well, the stock is literally an asset. It’s numeraire is the currency in which it is quoted.

It gets tricky with futures, because it can be both asset and liability (it’s technically a derivative). Instrument makes more sense (as said in the other answer). Perhaps instrument is the most generic. You can then subclass it to get more precise naming and features.

  • $\begingroup$ Thank you! this is very helpful. I think Instrument sounds right to me based on your and madilyn's answer $\endgroup$ – Evert Feb 21 '19 at 4:19

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