Market sentiment, also known as investor attention, is the general prevailing attitude of investors as to anticipated price development in a market. This attitude is the accumulation of a variety of fundamental and technical factors, including price history, economic reports, seasonal factors, and national and world events. If investors expect upward price movement in the stock market, the sentiment is said to be bullish. On the contrary, if the market sentiment is bearish, most investors expect downward price movement. Market participants who maintain a static sentiment, regardless of market conditions, are described as permabulls and permabears respectively. Market sentiment is usually considered as a contrarian indicator: what most people expect is a good thing to bet against. Market sentiment is used because it is believed to be a good predictor of market moves, especially when it is more extreme. Very bearish sentiment is usually followed by the market going up more than normal, and vice versa. A bull market refers to a sustained period of either realized or expected price rises, whereas a bear market is used to describe when an index or stock has fallen 20% or more from a recent high for a sustained length of time.
Market sentiment is monitored with a variety of technical and statistical methods such as the number of advancing versus declining stocks and new highs versus new lows comparisons. A large share of the overall movement of an individual stock has been attributed to market sentiment. The stock market's demonstration of the situation is often described as all boats float or sink with the tide, in the popular Wall Street phrase "the trend is your friend". In the last decade, investors are also known to measure market sentiment through the use of news analytics, which include sentiment analysis on textual stories about companies and sectors.
Theory of investor attention
A particular thread of scientific literature connects results from behavioural finance, changes of investor attention on financial markets, and fundamental principles of asset pricing: Barberis et al. (1998), Barberis & Thaler (2003), and Baker & Wurgler (2007). The authors argue that behavioural patterns of retail investors have a significant impact on market returns. At least five main approaches to measuring investor attention are known today in scientific literature: financial market-based measures, survey-based sentiment indexes, textual sentiment data from specialized on-line resources, Internet search behavior, and non-economic factors.
First approach
According to the first approach, investor attention can be approximated with particular financial market-based measures. According to Gervais et al. (2001) and Hou et al. (2009), trading volume is a good proxy for investor sentiment. High (low) trading volume on a particular stock leads to appreciating (depreciating) of its price. Extreme one-day returns are also reported to draw investors’ attention (Barber & Odean (2008)). Noise traders tend to buy (sell) stocks with high (low) returns. Whaley (2001) and Baker & Wurgler (2007) suggest Chicago Board Options Exchange (CBOE) Volatility Index (VIX) as an alternative market sentiment measure. Credit Suisse Fear Barometer (CSFB) is based on prices of zero-premium collars that expire in three months. This index is sometimes used as an alternative to VIX index. The Acertus Market Sentiment Indicator (AMSI) incorporates five variables (in descending order of weight in the indicator): Price/Earnings Ratio (a measure of stock market valuations); price momentum (a measure of market psychology); Realized Volatility (a measure of recent historical risk); High Yield Bond Returns (a measure of credit risk); and the TED spread (a measure of systemic financial risk). Each of these factors provides a measure of market sentiment through a unique lens, and together they may offer a more robust indicator of market sentiment. Closed-end fund discount (the case when net asset value of a mutual fund does not equal to its market price) reported to be possible measure of investor attention (Zweig (1973) and Lee et al. (1991)).