The complete suite of technical indicators available on Yahoo! Finance can be accessed by clicking the "Technical Analysis" link under "Charts" in the left column.

Technical indicators are grouped into two sub-categories, "Indicators" and "Overlays." Overlays result in supplemental data being superimposed on a price chart, while indicators add supplemental data below the main price chart as a separate graph.

The following page describes in detail all of the indicator and overlay elements.

Indicators:

• MACD (Moving Average Convergence/Divergence): MACD is a trend-following momentum indicator that shows the relationship between two moving averages of prices. MACD is represented as the difference between a 26-day and 12-day exponential moving average (EMA). A 9-day EMA, referred to as the "signal" (or "trigger") line, is plotted on top of the MACD to indicate buy/sell opportunities.
  According to Stephen Aechlis, the MACD is most effective in wide-swinging trading markets. He also indicates the three standard ways to interprete the MACD (as quoted from his book Technical Analysis from A to Z):
  
  • Crossovers
    The basic MACD trading rule is to sell when the MACD falls below its signal line. Similarly, a buy signal occurs when the MACD rises above its signal line. It's also popular to buy/sell when the MACD goes above/below zero.
  • Overbought/Oversold Conditions
    The MACD is also useful as an overbought/oversold indicator. When the shorter moving average pulls away dramatically from the longer moving average (i.e., the MACD rises), it's likely that the security price is overextending and will soon return to more realistic levels. MACD overbought and oversold conditions exist vary from security to security.
  • Divergences
    A indication that an end to the current trend might be near occurs when the MACD diverges from the security. A bearish divergence occurs when the MACD is making new lows while prices fail to reach new lows. A bullish divergence occurs when the MACD is making new highs while prices fail to reach new highs. Both of these divergences are most significant when they occur at relatively overbought/oversold levels.
• MFI (Money Flow): Measuring the strength of money flowing in and out of a security, the Money Flow Index (MFI) is a momentum indicator related to the similar relative strength index. The primary difference being that while the RSI only incorporates prices, the MFI accounts for volume.
  According to Stephen Achelis, the points of interpretation are as follows:
  "Look for divergence between the indicator and the price action. If the price trends higher and the MFI trends lower (or vice versa), a reversal may be imminent. Look for market tops to occur when the MFI is above 80. Look for market bottoms to occur when the MFI is below 20."
• ROC (Rate of Change): The Price Rate-of-Change (ROC) indicator displays the difference between the current price and the price x-time periods ago. The difference can be displayed in either points or as a percentage.
  According to Stephen Achelis, the interpretation of ROC is as follows:
  "The 12-day ROC is an excellent short- to intermediate-term overbought/oversold indicator. The higher the ROC, the more overbought the security; the lower the ROC, the more likely a rally. However, as with all overbought/over-sold indicators, it is prudent to wait for the market to begin to correct (i.e., turn up or down) before placing your trade. A market that appears overbought may remain overbought for some time. In fact, extremely overbought/oversold readings usually imply a continuation of the current trend. The 12-day ROC tends to be very cyclical, oscillating back and forth in a fairly regular cycle. Often, price changes can be anticipated by studying the previous cycles of the ROC and relating the previous cycles to the current market."
• RSI (Relative Strength Index):
  The Relative Strength Index (RSI) measures the price of a security against its past performance to determine its internal strength (in an attempt to quantify the security's price momentum). The default trading period used to calculate RSI is set to 14.
  According to Stephen Achelis:
  "A popular method of analyzing the RSI is to look for a divergence in which the security is making a new high, but the RSI is failing to surpass its previous high. This divergence is an indication of an impending reversal. When the RSI then turns down and falls below its most recent trough, it is said to have completed a "failure swing." The failure swing is considered a confirmation of the impending reversal."
• Stochastics: The Stochastic indicator compares where a security's price closed relative to its price range over a given time period. The Stochastic indicator is displayed as two line. One line is called "%K." A second line, called "%D," is a moving average of %K. The default %K and %D values used to calculate the Slow Stochastic are set to 15 and 5, respectively. The default %K and %D values used to calculate the Fast Stochastic are set to 5 and 3, respectively.
  According to Stephen Achelis, these are the three popular ways to interpret:
  
  • Buy when the Oscillator (either %K or %D) falls below a specific level (e.g., 20) and then rises above that level. Sell when the Oscillator rises above a specific level (e.g., 80) and then falls below that level.
  • Buy when the %K line rises above the %D line and sell when the %K line falls below the %D line.
  • Look for divergences. For example, where prices are making a series of new highs and the Stochastic Oscillator is failing to surpass its previous highs.
• Volume: Represents the number of shares transacted for the price period. As there is a seller for every buyer, think of the trading volume as half of the number of shares transacted. That is, if A sells 100 shares to B, the volume is 100 shares.
• Volume +MA: Represents the number of shares transacted every day. In addition, a 13-day volume EMA overlay is used to provide additional information on the volume trend.
• Williams %R: The Williams %R indicator seeks to measure overbought/oversold levels.
  According to Stephen Achelis:
  "Readings in the range of 80 to 100% indicate that the security is oversold while readings in the 0 to 20% range suggest that it is overbought."

Overlays

• Bollinger Bands: Bollinger Bands are a type of envelope plotted at standard deviation levels above and below a moving average. Since standard deviation is a measure of volatility, the bands are self-adjusting—widening during volatile markets and contracting during calmer periods. The default trading period and standard deviations used to calculate the Bollinger Bands are set to 20 and 2, respectively.
  Stephen Aechlis, author of Technical Analysis from A to Z, has the following to say about interpreting this indicator:
  "The basic interpretation of Bollinger Bands is that prices tend to stay within the upper- and lower-band. The spacing between the bands varies based on the volatility of the prices. During periods of extreme price changes (i.e., high volatility), the bands widen to become more forgiving. During periods of stagnant pricing (i.e., low volatility), the bands narrow to contain prices."
• Parabolic SAR: Also known as the "Parabolic Time/Price System," this indicator is used to set trailing price stops and is usually referred to as the "SAR" (stop-and-reversal). The default step period used to calculate the Parabolic SAR is set to 0.02.
  On the interpretation of Parabolic SAR, Stephen Aechlis, author of Technical Analysis from A to Z, has the following to say:
  "The Parabolic SAR provides excellent exit points. You should close long positions when the price falls below the SAR and close short positions when the price rises above the SAR. If you are long (i.e., the price is above the SAR), the SAR moves up every day, regardless of the direction the price is moving. The amount the SAR moves up depends on the amount that prices move."
• Splits: Although it is not particularly associated with technical analysis, this overlay displays the date of historical splits events for a stock via gray triangle indicators. Further details on the exact date of a split and the specific split ratio is available at the bottom of the price chart.
• Volume: Represents the number of shares transacted every day. As there is a seller for every buyer, think of the trading volume as half of the number of shares transacted. That is, if A sells 100 shares to B, the volume is 100 shares.

Unlike the display settings, where only one option can be selected at a time, several moving averages, indicators, and overlays can be enabled at once. To do so, simply select the items you wish to enable by clicking the appropriate links. When a moving average, indicator, or overlay is activated, it is bolded. To toggle the selected item off, simply click the link a second time.

Please note that a maximum of four overlays and moving averages can be activated at any one time. If you have reached this limit and click a new overlay or moving average, the most recent item selected is enabled, and the oldest item selected is turned off. The same limit applies to the indicators (four-item limit at any given time).