Average cost price = total cost of shares currently held (including fees) ÷ number of shares currently held
When you buy or sell, your average cost can go up or down. With Hatch, sales are treated on a first-in first-out (FIFO) basis, meaning that the shares you bought earliest are treated as the first to be sold when calculating average cost.
Example: Jane buys 1 share of the same stock every month.
Month 1: stock price is $100, brokerage fee is $3, Jane now has 1 share
Average cost = (100+3) / 1 = $103
Month 2: stock price is $200, brokerage fee is $3, Jane now has 2 shares
Average cost = (100+3 + 200+3) / 2 = $153
Month 3: stock price is $300, brokerage fee is $3, Jane now has 3 shares
Average cost = (100+3 + 200+3 + 300+3) / 3 = $203
Month 4: Jane then sells 1 share of the stock, Jane now has 2 shares (we treat her sold share as the first one she bought)
Average cost = (200+3 + 300+3) / 2 = $253
Fees-inclusive calculation update
From February 20th 2026 our average cost price calculation was updated to include brokerage fees paid. This was backdated for buys as far back as 1st January 2024, but no further, so the cost calculation for your holdings may differ depending on when you bought your shares:
Our fees are the same, you haven’t been charged anything extra. The only change is to reflect the fees you paid when buying. For new buys, the cost will update to reflect fees after the trade settles (generally 1 business day after your order completes).
💡 Note: There are some exceptions (like transfers) which mean the cost price may or may not include fees. If you have questions about your specific situation, you can reach out to our friendly team.