What Is Cost Basis (Net of Fees) and Why Does It Differ From Your Broker's Number?

Cost basis (net) is the average price per share you actually paid for a position, with commission, platform fees, stamp duty and other buy-side charges folded in. It is the starting line for unrealised profit or loss: you are only genuinely ahead when the price is above this figure, not merely above the trade price.

How it is calculated

Step one is the gross cost: add up "price × shares" for every buy and divide by total shares to get a weighted average. If you sell part of the position, the remaining shares keep their cost at the average as it stood. Once a sell takes the share count to zero, that cost record ends; a later buy starts a fresh average from its own price instead of blending with a position that no longer exists.

Step two adds fees: the total charges incurred when buying those shares are divided by the share count and added to the gross cost. For HK stocks the charges usually include commission (with a minimum), a platform fee, stamp duty and small regulatory levies; for A-shares stamp duty applies on the sell side only; for US stocks commission and platform fees are charged per share. The broker preset you choose in settings sets these rates.

Selling triggers another round of charges, so real profit or loss is a little smaller than "price minus cost".

Rules of thumb

Price vs net cost	What it usually means
Below cost	Unrealised loss; the deeper it goes, the disproportionately larger the recovery needed
Within ±2% of cost	Roughly flat; the sell-side fee alone can decide the sign
5% to 10% above cost	A common take-profit reference band
20% or more above cost	Most mechanical rules consider scaling out or a trailing stop

These are not rules, only reference levels people commonly use. Useful stop and target levels are written down before the trade and tested — see take-profit and stop-loss rules.

What it does not tell you

• What the stock is worth. Cost is your personal history; the market neither knows nor cares what you paid.
• Opportunity cost. Holding a stock two years to get back to break-even can be a loss compared with what the money could have done elsewhere.
• Your tax basis. Jurisdictions define cost differently (first-in-first-out, specific lots, and so on), which may not match this weighted average.

In Stock Compass

On a holding's card, "Cost" sits beside the ticker: the total position cost first, then the share count and the net cost per share. Hovering shows the breakdown — gross cost, buy fees and estimated sell fees. When a stock was bought in several batches the lots expand below the card. The row's unrealised P&L percentage includes fees on both legs, so it reads slightly lower than the gross figure in a broker app; the portfolio-level P&L at the top of the page uses the gross formula so that it matches the asset header.

The verdict's risk dimension uses it too: when a holding is down 15% or more, it notes that the position is "past the trigger point of most stop-loss rules".

Cost itself is not a strategy-rule indicator — it is your private data. Its rule-side counterparts are the three position indicators: floating_gain_pct (e.g. floating_gain_pct > 10), floating_loss_pct (e.g. floating_loss_pct > 8) and holding_days. All are computed against the net cost and apply only to holdings. For the HK fee schedule in detail see Hong Kong stock trading fees; for a combined read on the state of a holding see position health.