Stochastic K

Stochastic %K is a momentum oscillator that compares a security's closing price to its price range over a specified period, typically 14 days. Developed by George Lane, %K shows where the current close falls within the recent high-low range. The theory is that prices tend to close near highs in uptrends and near lows in downtrends, so %K helps identify momentum and potential reversals.

The %K calculation:

%K = ((Current Close - Lowest Low) / (Highest High - Lowest Low)) × 100

Where:
Lowest Low = Lowest price over lookback period (14 days)
Highest High = Highest price over lookback period (14 days)

Example:

14-day High: $55
14-day Low: $45
Current Close: $52
%K = (($52 - $45) / ($55 - $45)) × 100 = 70%

Interpreting %K levels:

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%K > 80: Overbought; price near top of recent range

%K 50-80: Bullish momentum; price in upper half of range

%K = 50: Neutral; price at midpoint of range

%K 20-50: Bearish momentum; price in lower half of range

%K < 20: Oversold; price near bottom of recent range

Why %K matters:

• Momentum indicator: Shows buying/selling pressure
• Range context: Places price within recent trading range
• Reversal signals: Extremes may indicate exhaustion
• Paired with %D: Crossovers generate trading signals

%K types:

• Fast %K: Raw calculation; very sensitive
• Slow %K: Smoothed version (3-period SMA of Fast %K)

Trading signals:

• %K crosses above %D: Bullish signal
• %K crosses below %D: Bearish signal
• Oversold cross up: Buy signal when %K crosses %D below 20
• Overbought cross down: Sell signal when %K crosses %D above 80

Limitations:

• Can stay extreme: Strong trends keep %K overbought/oversold
• False signals: Frequent crosses in choppy markets
• Lagging component: Smoothed versions delay signals

%K is most useful when combined with %D and used in conjunction with trend analysis. The Stochastic oscillator provides early momentum signals but requires context to avoid acting on false readings in trending markets.