What trading actually costs

Every real trade pays two costs most beginners never see itemized: a fee and the spread. Both are small on any single trade, which is exactly why they matter — they compound with every round trip.

The fee is what the exchange charges to execute. At major US crypto exchanges, entry-level “taker” fees run around 0.4% to 0.6% of the trade's value. Aureus charges a 0.40% practice fee on crypto trades, taken from your practice cash as its own labeled line — modeled on the real thing so the arithmetic you practice is the arithmetic you'd meet.

The spread is the gap between the highest price buyers are offering and the lowest price sellers are asking. A real buy fills at the higher side; a real sell at the lower. Crossing it costs money even when no fee is charged — it's how “zero-commission” trading is never quite free.

Aureus deliberately does not model the spread, because we have no honest bid-and-ask source to model it from — and the trade ticket says so. That makes practice results flatter than real ones in a second way, beyond the fee: a strategy that only just breaks even here would lose money crossing real spreads.

Why this is worth knowing: frequent trading multiplies both costs. Ten round trips pay the friction twenty times. Nothing here says how often you should trade — but the costs of trading often are worth seeing clearly, and a practice account that hid them would be teaching the wrong arithmetic.