Historical FX (on cost basis)
Applying the exchange rate that prevailed on the day of each transaction, not today's rate retroactively.
When you hold a foreign-currency position and report performance in your home currency, two different conventions exist:
**Today's-rate-retroactive (the bad way)** — take today's FX rate and apply it to every historical transaction. Easy. Wrong. Inflates or deflates historical performance depending on which way the currency moved since you bought.
**Historical FX on cost basis (the honest way)** — for each transaction, lock in the FX rate of the trade date. Cost basis in your home currency is the sum of those locked-in costs. Performance figures reflect the *actual* currency journey of the position, not a retroactive rewrite.
A concrete example: a European investor who bought Apple at $200 in 2019 (EUR/USD = 1.13) had a cost basis of €177. Today AAPL is at $250 and EUR/USD = 1.08. Today's-rate-retroactive says: cost was $200 × 1/1.08 = €185, return = €231 − €185 = +25%. Historical FX says: cost was €177, return = €231 − €177 = +30%. Same euros in the bank — but only the second number is what actually happened.
Evibe tracks 70+ currency pairs continuously, applies historical FX to every transaction, and reports in your portfolio's reference currency without rewriting history.