balance --gain's functionality needs to be described in detail.
Related:
https://www.reddit.com/r/plaintextaccounting/comments/141fyoq/hledger_investment_gain_calculation_problem suggests it sometimes shows realised gain, not just unrealised gain.
Some examples based on the above:
decimal-mark ,
commodity 1.000, TRY
commodity EUPWR 1.000,00
2023-04-12 * Buy stock
Assets:Bank -1015 TRY
Assets:Investment:Stock:EUPWR 25 EUPWR @ 40,6 TRY
; with just the above:
;
; $ hledger bal --gain EUPWR
; EUPWR 25,00
; -1.015,0 TRY Assets:Investment:Stock:EUPWR
; --------------------
; EUPWR 25,00
; -1.015,0 TRY
; with an inferred market price:
; $ hledger bal --gain EUPWR --infer-market-prices
; --------------------
; 0
; with a declared market price:
P 2023-05-30 EUPWR 94,65 TRY
; $ hledger bal --gain EUPWR
; 1.351,2 TRY Assets:Investment:Stock:EUPWR
; --------------------
; 1.351,2 TRY
; with the stock partly sold:
2023-05-11 * Sell part of stock
Assets:Bank 603,72 TRY
Assets:Investment:Stock:EUPWR -10 EUPWR @ 60,3728 TRY
; $ hledger bal --gain EUPWR
; 1.008,4780 TRY Assets:Investment:Stock:EUPWR
; --------------------
; 1.008,4780 TRY
; with the stock fully sold:
2023-05-12 * Sell rest of stock
Assets:Bank 905,59 TRY
Assets:Investment:Stock:EUPWR -15 EUPWR @ 60,3728 TRY = 0 TRY
; $ hledger bal --gain EUPWR
; 494,3200 TRY Assets:Investment:Stock:EUPWR
; --------------------
; 494,3200 TRY