I have a quick accounting question relating to the Average-Cost-basis method for my tax-return. If I sell a partial amount of shares does that affect my cost base later on?
e.g.,
Day 1) I buy 2 shares at $5
Day 2) I buy 2 shares at $10
Day 3) I sell 3 shares at $15
Day 4) I buy 2 shares at $20
When calculating my Average cost-basis at day 3 I understand that it'd be $7.5 per share = ($5x2)+($10x2) / 4
But how would I calculate my Average cost-basis per share on day 4? Is it just ($5x2)+($10x2)+($20x2) / 6 = $11.67 per share or is the fact that I sold 3 of my shares relevant?
Alternatively would the average cost basis be the 1 unit of $7.50 left and the 2 units of $20 so ($7.50 + $20x2)/3 = $15.83 per share?
Any help would be appreciated, thanks.