Track investments

A simple example using prices:

2017/1/1 opening balances
  (assets:depot)  $3000

2017/1/2 buy shares at $200
  ; let's assume no fees
  assets:shares   10 TSLA @ $200  ; transaction/purchase price
  assets:depot

; market price, has jumped since yesterday's purchase!
P 2017/1/3 TSLA $250

Some reports. We start with $3000. After the 1/2 purchase, we have $1000 remaining and 10 TSLA shares:

$ hledger -f t.j bal assets --flat -HD
Ending balances (historical) in 2017/01/01-2017/01/02:

               ||  2017/01/01     2017/01/02 
===============++============================
 assets:depot  ||       $3000          $1000 
 assets:shares ||           0        10 TSLA 
---------------++----------------------------
               ||       $3000 $1000, 10 TSLA 

Show the shares's value at cost, with -B/--cost:

$ hledger -f t.j bal assets --flat -HD -B
Ending balances (historical) in 2017/01/01-2017/01/02:

               ||  2017/01/01  2017/01/02 
===============++=========================
 assets:depot  ||       $3000       $1000 
 assets:shares ||           0       $2000 
---------------++-------------------------
               ||       $3000       $3000 

Show the shares's value using the latest applicable market price, with -V/--value. A $500 capital gain is apparent in the totals:

$ hledger -f t.j bal assets --flat -HD -V
Ending balances (historical) in 2017/01/01-2017/01/02:

               ||  2017/01/01  2017/01/02 
===============++=========================
 assets:depot  ||       $3000       $1000 
 assets:shares ||           0       $2500 
---------------++-------------------------
               ||       $3000       $3500 

This is about the limit of hledger's value-reporting abilities, currently.