Commission rounding on micro lots can quietly change the cost
Posted: Sat Oct 31, 2026 10:20 am
A broker charges 3.50 dollars per lot per side. On 0.01 lots, that's 3.5 cents, which has to be rounded to a whole cent. Depending on the system, it may round up to 4 cents, down to 3, or to the nearest.
Over thousands of trades, the difference is large. Rounding up on every trade raises the effective commission by around fifteen percent. Rounding down lowers it by the same amount.
Some brokers apply a minimum commission per ticket, which makes small trades far more expensive in proportion. Checking is simple: open and close a few trades at the smallest size and compare the charged amount with the stated rate. Five or six round trips are enough to see the pattern, and the statement shows the exact charge for each one.
Has the charged commission on small lots ever differed from the advertised rate?
Over thousands of trades, the difference is large. Rounding up on every trade raises the effective commission by around fifteen percent. Rounding down lowers it by the same amount.
Some brokers apply a minimum commission per ticket, which makes small trades far more expensive in proportion. Checking is simple: open and close a few trades at the smallest size and compare the charged amount with the stated rate. Five or six round trips are enough to see the pattern, and the statement shows the exact charge for each one.
Has the charged commission on small lots ever differed from the advertised rate?