The Real Cost of Trading
Commission is usually the smallest cost and the only visible one. The spread, the slippage and the tax treatment are larger and mostly invisible.
MadStockAlerts Research · Updated August 28, 2026
What to take away
- Zero commission does not mean zero cost.
- The bid-ask spread is paid on every round trip whether or not it is itemised.
- Costs scale with turnover, so frequency multiplies everything.
- Tax treatment can be the largest single cost for a short-horizon approach.
- Reducing turnover is the only lever that acts on every cost at once.
MAD Academy Training Video · 0:45
The Costs That Are Not on the Statement
Commission is the smallest and most visible cost. Spread, slippage, taxes and financing are larger and mostly invisible.
This lesson is part of a Stock Alerts + Tools plan.
The full list
| Cost | Visible? | Typical size |
|---|---|---|
| Commission | Yes | Often zero on US equities |
| Bid-ask spread | No | From a fraction of a basis point to several percent |
| Slippage | No | Grows with order size and volatility |
| Borrow fee on shorts | Partly | Negligible to very large |
| Financing on margin | Yes | A rate on the borrowed balance |
| Regulatory fees | Yes | Small, on sales |
| Tax | Later | Frequently the largest cost of all |
The pattern is that the visible costs are the small ones. Commission went to zero and was widely reported as trading becoming free, which is true of the line item and not of the transaction.
Turnover multiplies everything
A cost of 0.2 percent per round trip is trivial on one trade. Repeated two hundred times a year it is forty percent of capital, which no realistic edge overcomes.
annual cost drag = round-trip cost x number of round trips per year
This is why frequency is a risk parameter rather than a style preference. The higher the turnover, the larger the edge required per trade simply to break even, and costs are certain while the edge is not.
Scroll the chart sideways to see all of it.
Tax
In the United States, gains on positions held a year or less are taxed as ordinary income, while gains on longer holdings receive preferential rates. The difference can exceed every other cost combined, and it falls entirely on short-horizon activity.
Wash sale rules further disallow a loss when a substantially identical security is repurchased within thirty days, which affects anyone trading the same names repeatedly. A loss that cannot be recognised this year is not a loss that has been avoided; it is a deferral with record-keeping attached.
This is a description of the rules and not tax advice; the specifics depend on individual circumstances, on account type, and on jurisdiction.
Reducing them
- Trade liquid securities, where the spread is a rounding error rather than a cost.
- Use limit orders where immediacy is not required, which supplies liquidity instead of paying for it.
- Avoid the first and last minutes unless the trade specifically requires them.
- Reduce turnover, which is the only lever that acts on every cost at once.
The costs that do not appear on a statement
Commission is visible, small and frequently zero, which is why it is the cost most discussed and the least important. The costs that determine outcomes are the ones no line item reports.
| Cost | Where it shows up | Rough scale |
|---|---|---|
| Spread | In the fill price, never itemised | Cents on a liquid name, percent on a thin one |
| Market impact | In the fill price, at size | Grows with order size relative to depth |
| Financing on margin | A monthly interest charge | An annual rate, on the borrowed portion |
| Borrow cost on a short | A daily fee | Trivial on most names, extreme on hard-to-borrow ones |
| Tax on short holding periods | The following April | Often the largest single item |
| Opportunity cost | Nowhere | Unmeasurable and real |
Two of these deserve particular attention because they are asymmetric. Borrow cost on a hard-to-borrow security can exceed an annualised rate that no reasonable thesis overcomes, and it is charged daily whether or not the position works. Tax on short holding periods converts a gross return into a materially smaller net one, and it is levied on the gains while the losses offset only within their own rules.
How holding period changes the tax arithmetic
In the United States, a position held for a year or less is taxed at ordinary income rates when it is closed at a gain, and one held longer than a year is taxed at long-term capital gains rates. The difference between those two rates is frequently larger than every other cost of trading combined, and it is a direct function of the holding period rather than of the quality of the decision.
The consequence is that a short-horizon method has to clear a materially higher gross return to deliver the same net return as a longer-horizon one. This is arithmetic rather than an argument for either horizon: a method that produces enough gross return can absorb it, and one that does not was never as close to the line as it looked.
Everything here describes how the rules work. It is not tax advice, individual circumstances differ enormously, and the treatment of losses, wash sales and account types changes the arithmetic in ways only a professional can apply to a particular situation.
A second point that is easy to miss: tax is levied on realised gains in the year they are realised, whether or not the proceeds are still invested. A profitable year that ends with everything reinvested still produces a bill, and the cash for it has to come from somewhere.