Is trading gambling?
Work out the expected value of one roulette bet. You put 10 USD on 27, a straight-up bet, on an American wheel with 38 pockets (the numbers 1 to 36, a 0 and a 00). If the ball lands on 27, the casino pays 35 to 1, so you win 350 USD; otherwise you lose your 10 USD. The ball lands on 27 with probability 1/38: Each 10 USD bet loses 0.53 USD on average, 5.26% of the stake. A legal lottery does no better: Pennsylvania’s rules for Powerball allocate 50% of gross sales to the prize pool, so the average ticket buyer loses half of what the tickets cost. At roulette or a lottery you can change neither the probability nor the payout. The house fixes both so that it always comes out ahead, and your EV is always below 0. Trading is different: no one fixes those two numbers for you. Your win rate and your RR (reward to risk, , the average win divided by the average loss) depend on the strategy you use. EV is zero when : that is the breakeven line on the chart below, and every strategy is a point on the chart. A strategy that wins 50% of its trades needs RR = 1 to break even, one that wins 40% needs RR = 1.5, and one that wins 25% needs RR = 3. So is trading gambling? It depends on where you stand on the chart. Below the breakeven line, or without knowing where you stand, you are trading no differently from gambling. Above the line, you are a profitable trader.Why do some traders still lose with a positive EV?
Say a strategy wins 35% of its trades, makes 200 USD on each winner and loses 100 USD on each loser. It sits above the breakeven line (RR = 2), and its EV is +5 USD per trade. The chart below simulates 100 people who trade this strategy, 1,000 trades each, and draws each person’s PnL (cumulative profit and loss).- Simulation
- Python code
Read next
Backtesting
Estimating a strategy’s expected value from historical data.
Portfolio and risk
How much capital to put into each trade to survive a losing streak.

