When you sell a position you only partially own — say you bought 30 shares of VWCE at €100, another 30 at €110, and now you're selling 40 — the gain you "realize" depends entirely on which lots you match.
There are three common rules:
- FIFO (first-in, first-out): match against your oldest buys first.
- LIFO (last-in, first-out): match against your most recent buys.
- Average cost: blend every lot together into one weighted price.
FolioView uses FIFO, the same convention most European brokers and tax authorities default to. It's also the most defensible — every realized gain points to a specific historical buy you can audit.
Multi-currency wrinkle
For a USD stock bought on a EUR portfolio, FolioView tracks cost basis in both currencies. So the realized P/L line on your dashboard separates the price return (what the stock actually did) from the FX return (what the currency move did to your euro-denominated wealth). Both matter; conflating them hides whether your gain is real or just dollar weakness.
What this looks like in practice
Open the Trades page in the app. Every realized line shows: which buy lot it matched against, the cost basis at the time, the proceeds, and the gain in your home currency. No black boxes — every number traces back to a row in your CSV.
