@Jack100000
Thanks for the detailed explanation! Luckily I used TD ameritrade, so the 1099 B does come with cost factors, though it is probably not perfect. Can you please help me to check whether what I am thinking below is correct?
Assume I bought 100 shares in 02/2021, I paid my first expense on 3/3/2021. The CBF is 0.three zeros and 339295, the proceed for selling the underlying gold is $5.4, the cost basis I calculated using CBF*(my cost) is close to $5.59, so I actually should report a loss of -$0.19 here.
On 4/7 I paid my second expense. The CBF is 0.three zeros and 344745, so the cost is $5.68, while the reported proceed is $5.6, so again, I claim a loss of -$0.08 here.
Then when I sold these 100 shares in 04/2021, I should deduct that $5.59+$5.68 from the money I paid to make the real cost basis.
Technically, it is a moot action for short term trade, isn't it?
The SPDR spec says I need to pro-rate to date, the above calculation did not. The error margin is quite small based on the calculation.
