Building a Stock Trading Plan

Most traders have opinions about the market. Very few have a trading plan. The difference is not semantics: an opinion is a belief about where prices might go; a trading plan is a complete written specification of the decisions, rules, and processes that govern capital deployment under all foreseeable conditions. Opinions exist in the mind and shift with news flow, emotional state, and recency bias. A genuine trading plan exists on paper, is consulted before and after every session, and does not change based on the events of a single day. Professional trading desks, proprietary trading firms, and institutional portfolio managers operate from detailed written mandates for structural reasons — the same structural reasons apply at every scale.

1. What a Trading Plan Actually Contains

A genuine trading plan is operationally specific. Every section must be written so that a competent person reading it for the first time could execute every trade without asking a clarifying question. Vague language is a symptom of unclear thinking: “buy quality breakouts” is not a plan; “buy the first close above a multi-week horizontal resistance level on RVOL > 2.0 with a stop below the breakout candle’s low, sized for 1% account risk, targeting the measured move” is a plan.

The complete trading plan contains nine distinct sections:

1. Strategy and edge statement — what the strategy is, what inefficiency it exploits, and the evidence that the edge exists
2. Universe definition — which stocks or markets are eligible; filters for size, liquidity, sector
3. Setup criteria — precise technical and/or fundamental conditions required before any trade is considered
4. Entry rules — specific entry trigger, order type, and timing
5. Stop-loss rules — stop type, level determination, and conditions that change the stop
6. Profit-taking rules — first target, second target, trailing stop activation, full exit conditions
7. Position sizing rules — default size calculation, maximum single position, maximum total exposure, binary-event adjustments
8. Risk controls — daily loss limit, weekly drawdown limit, maximum consecutive losses before mandatory review
9. Performance review process — when, how, and what metrics trigger strategy modification

2. Strategy and Edge Statement

The edge statement is the most intellectually demanding section of the trading plan because it requires the trader to articulate, precisely, why the strategy should work. “Because it worked in my backtest” is not an edge statement; it is a data observation. An edge statement identifies the market inefficiency being exploited: “the strategy exploits post-earnings announcement drift (PEAD), the documented tendency of stocks that beat earnings expectations to outperform the market for 4–8 weeks, arising from investor underreaction to serial earnings correlations.”

An edge statement must also acknowledge the conditions under which the edge is likely absent. A trend-following edge disappears in choppy, low-trend markets; a mean-reversion edge disappears in strong trending markets. The plan must specify the regime conditions that activate and deactivate the strategy, and the mechanism for identifying regime transitions in real time. This connects to the backtesting standards from Course 34: the edge statement should be consistent with the out-of-sample evidence for the strategy.

3. Universe Definition and Scanning

The universe definition specifies precisely which securities are eligible for trading. A well-defined universe has the following characteristics: (1) it is large enough to provide a continuous flow of setups — at least 50–200 stocks for most strategies; (2) it excludes securities where execution quality is insufficient (e.g., stocks with average daily volume below 500,000 shares); (3) it excludes securities where the strategy has known failure modes (e.g., excluding biotech binary-event stocks from a trend-following universe); and (4) it is defined by objective, observable criteria rather than subjective selection.

The universe should be updated periodically (monthly or quarterly) to reflect changes in market capitalisation, liquidity, and sector composition. A stock that was a valid universe member six months ago due to strong liquidity may have experienced volume collapse that makes it ineligible today. Universe maintenance is a systematic process, not a one-time exercise. Using Alpaca’s API with automated universe screening, or running daily scans through a broker’s screening tool, keeps the eligible set current without requiring manual judgment at the trading decision stage.

4. Entry, Stop, and Exit Rules in Complete Specificity

The entry, stop, and exit sections must leave no room for interpretation. The test: can you write these rules into code without additional assumptions? If yes, the rules are specific. If the rules require human judgment to translate into executable instructions, they are insufficiently specified and will be applied inconsistently across emotional states.

Example entry rule (specific): “Enter a long position on the first daily close above the highest close of the prior 20 trading days, provided the day’s volume exceeds the 20-day average volume, provided the stock is in a bullish EMA stack (close > 21 EMA > 50 EMA on daily), and provided the close is more than 1 ATR above the 20-day high to filter micro-breakouts. Enter at the open of the following session at market.”

Example entry rule (not specific): “Buy when price breaks out to new highs with good volume and positive momentum.” This is unexecutable; every criterion is subjective.

Stop rules should specify: the stop level calculation method (ATR multiple, percentage from entry, structural level), the stop order type (market stop vs stop-limit), conditions under which the stop is adjusted (trailing stop activation criteria), and the response to gap-through events (e.g., “if price opens below the stop level, exit at market on the open regardless of gap size”). Use our stock position size calculator to mechanically derive share count from the entry, stop, and account risk percentage specified in the plan.

5. Position Sizing Framework

The position sizing section specifies the default risk per trade (typically 1% of account equity for active traders, 2% maximum), the maximum single position as a percentage of account (typically 10–25%), the maximum gross exposure across all open positions (typically 80–150% for long-only, less if short positions are included), and any event-specific adjustments (e.g., “reduce to 0.25% risk per trade for any position held through an earnings announcement”).

The framework must also specify the response to account equity changes. As account equity grows through profitable trading, positions sized at 1% of equity grow proportionally — which is correct and captures the compounding benefit of successful trading. As account equity falls through losses, positions size down proportionally — which provides automatic loss limitation during drawdowns. This geometric sizing approach is the standard professional method and differs critically from fixed-share-count sizing, which does not adapt to equity changes.

Worked example. Account equity: $30,000. Risk per trade: 1% = $300. Entry at $85.00, stop at $81.50, risk per share = $3.50. Shares = $300 ÷ $3.50 = 85 shares. Position value = 85 × $85 = $7,225 (24% of account). If this exceeds the single-position maximum (e.g., 25% of account), size down to 25% maximum: $7,500 ÷ $85 = 88 shares, but the dollar risk increases slightly to 88 × $3.50 = $308 (1.03% of account — acceptable rounding). All of this arithmetic is handled instantly by our stock position size calculator.

6. Risk Controls: Daily Loss Limits and Drawdown Protocols

Risk controls are the most important and least followed section of most trading plans. Their purpose is to prevent the loss-aversion and revenge trading dynamics documented in Course 33 from converting a manageable drawdown into an account-threatening one. They must be written as inviolable rules, not guidelines.

• Daily loss limit: “If realised + unrealised losses reach 2% of account equity at any point during the session, close all positions immediately and end the trading session for the day. No exceptions.” The daily limit should be 2–3 times the average losing trade size, providing enough buffer to absorb 2–3 normal losing trades before triggering, but small enough to prevent a single catastrophic day.
• Weekly drawdown review trigger: “If account equity falls 5% from the weekly starting value, reduce all new position sizes by 50% for the remainder of the week and conduct a mandatory strategy review before returning to full size.” This automatic size reduction during drawdowns reduces the magnitude of potential further losses while the trader investigates whether the drawdown reflects normal variance or a strategy breakdown.
• Maximum drawdown reset trigger: “If account equity falls 10% from its all-time high, cease all trading, review all open positions, and do not resume live trading until the strategy has been reviewed against backtesting standards and approved for continuation or modified.” A 10% maximum drawdown trigger from all-time high is a conservative professional standard; some traders use 15–20%, but lower thresholds protect capital during strategy failures.

7. Performance Review Process

The performance review process specifies how, when, and based on what data the strategy is evaluated and potentially modified. Without a defined review process, strategy changes are made impulsively in response to recent performance — abandoning strategies after drawdowns (right before they recover) or adding leverage after winning streaks (right before they correct).

The minimum review framework: (1) weekly review — basic performance check, journal review for execution errors, no strategy parameter changes; (2) monthly review — full performance metrics analysis (win rate, average win/loss, expectancy, Sharpe, maximum drawdown), comparison against historical baseline; (3) quarterly review — strategy regime analysis (are the conditions the strategy was designed for present in the current market?), parameter robustness check, potential strategy modifications with backtesting validation. The key rule: no strategy modification without completing at minimum 50 out-of-sample trades on the modified version before committing full capital. The trading journal from Course 39 provides the data infrastructure for these reviews.

Key Takeaways

• Stock Position Size Calculator — the mechanical implementation of the position sizing section of your trading plan for every trade.
• Stock P&L Calculator — model entry/target/stop scenarios before each trade to ensure the R:R is consistent with the plan’s requirements.