Common trading mistakes are repeatable errors that cost money whether or not the method itself has an edge: no written plan, moved stops, uneven size, trades to win back a loss, no review. Most share one kind of fix: a rule written in advance and a record that shows whether it was kept.
Below are twelve, in four groups. Each gives what the mistake looks like, why it costs, the fixing rule and how to spot it in a trading journal. The biases behind many of them are covered in trading psychology.
Planning mistakes
1. Trading without a written plan
Entries are decided on the chart in the moment; stop, size and exit come later, if at all. Each trade becomes a new decision under pressure, with no standard to review against. Fix: a written trading plan and a pre-trade checklist before every order. Spot it: trades with no plan saved before entry.
2. Holding through earnings by accident
A swing trade is still open on the report date because nobody checked it. A report can gap the price past the stop, so the loss is no longer limited to the plan (see stop vs stop-limit orders for gaps). Fix: check the date before entry and let the plan decide: exit, reduce size, or hold by choice. Spot it: tag trades held through a report and compare their realized R with the planned risk.
Risk and sizing mistakes
3. No stop, or a stop that moves
The stop is never placed, or is pushed away as the price nears it. A loss meant to be one unit of risk becomes two or three, and a few of those erase many ordinary wins. Fix: place the stop where the idea is wrong (stop-loss placement), enter it as an order with the trade, and move it only in the trade's favor. Spot it: any loss beyond 1R that was not a gap.
4. Risk per trade too large or uneven
One trade risks 0.5% of the account, the next 3% because it "looks better". Large risk turns a normal losing streak into a deep drawdown; uneven risk makes results reflect sizing more than the method. Fix: a fixed risk percentage, shares = risk ÷ (entry − stop), from the position size calculator; models are compared in position sizing methods, and the losing streak calculator shows how long losing runs last. Spot it: risk % values outside the plan's range.
5. Averaging down a loser
Buying more as the price falls to lower the average cost. Each addition enlarges a position that is already proving the idea wrong, and the stop usually moves lower with it. Fix: add only to positions that are working, under a written rule, never below the original stop. Spot it: several entry fills at falling prices (example below).
6. One bet placed several times
Five positions, all chip stocks. Each risks 1% on paper, but in a sector sell-off they fall together, so the real risk is closer to 5% on one idea. Fix: count one sector or theme as one bet and cap total open risk. Spot it: tag trades by sector or theme and look for days when several hit their stops together.
Execution mistakes
7. Revenge trading after a loss
An unplanned, often larger trade taken soon after a loss to win it back. It follows the last result, not a setup, so it carries the cost of a trade without the reason for one. Fix: a daily loss limit after which no new trades open, and normal or smaller size next session. Spot it: tag same-day trades after a loss and compare their expectancy with the rest.
8. Overtrading
Marginal setups and boredom trades, far more entries in a choppy week than the system signaled. Each extra trade adds costs and dilutes the trades that meet the rules. Fix: only setups that pass the checklist, with a cap on new positions per day or week. Spot it: setups or tags with negative results over a fair sample, and weeks where the trade count jumps while the plan did not change.
9. Ignoring costs and slippage
Commissions, spreads and slippage on stops are left out of the plan. They are small but charged on every trade, win or lose, and weigh most on short holds with small targets. Fix: estimate a setup's round-trip cost with the trading cost calculator and express it as a fraction of R. Spot it: record fees on every fill and compare results before and after fees by holding period.
10. Exits without rules
Winners are sold at the first small profit; losers are held until they "come back". The result is small wins and full losses, the reverse of what most methods need. Fix: write the exit before the entry: a target, a trailing stop or a time rule. Spot it: average win in R versus the planned target, and MAE and MFE for how much of each move was left behind.
Review mistakes
11. Changing the rules after a few losses
Three losses, and the stop is widened or the system dropped. A handful of trades says almost nothing about an edge, so new rules get fitted to noise, the same error as overfitting a backtest. Fix: change rules only at a scheduled review on a sample large enough to judge; fix execution errors at once. Spot it: trades since the last rule change; trading performance metrics explains why small samples mislead.
12. Not reviewing, or reviewing only the P&L
Trades are logged and never read again, or judged by profit alone. The same mistake returns, and lucky rule breaks get rewarded while good losses get punished. Fix: a weekly trade review that grades process apart from outcome and ends with one focus point. Spot it: the date of the last written review, and whether its focus point was checked.
Worked example: averaging down (illustrative numbers)
A $20,000 account risks 1% per trade, or $200. A stock is bought at $50 with a stop at $48: 100 shares, so 1R is $200. At $48, instead of exiting, another 100 shares are bought; the average cost drops to $49 and the stop moves to $46.
- If the new stop is hit: 200 shares × ($49 − $46) = $600, a 3R loss, or 3% of the account instead of the planned 1%.
- With 2:1 reward-to-risk, a full winner makes 2R, so making back this one trade takes one and a half winners.
- The journal shows two entry fills at falling prices, a stop below the planned one and a realized R of −3: three flags for one mistake.
In Clear Tape
The free trade journal holds most of these signals. A plan can be saved before entry with the planned entry, stop, targets, system, setup and thesis, so trades without one stand out. Each trade shows the planned R:R, risk in dollars and as a percentage of the account, and the realized R multiple, with P&L after fees. Trades can be tagged, for example "after loss" or "earnings", and statistics break results down by system or setup, tag, long or short, weekday and holding period. MAE and MFE are estimated from daily bars, so they are approximate. The AI trade score grades one closed trade's process (plan before entry, setup fit, entry, risk, management, discipline), never its P&L; limits per day are Free 1, Tools 10 and Pro 30. The AI period review on Tools (2 a week) and Pro (7 a week) summarizes recurring patterns and rule-following, and never recommends buying or selling. Details are on the trade journal page.
Two of these habits, holding losers longer than winners and trading right after a loss, already show in a broker's own records: the free trade history analyzer checks a CSV export for them.
For educational purposes only. Not investment advice.