## 2 Technical Analysis Indicators  
Technical analysis indicators are very useful tools for evaluating market trends, predicting price changes, and assessing the strength of a market. They can take different graphical or analytical forms. Specific values or combinations of values can be interpreted by a technical analyst, as indications to sell, buy, or hold an asset [27]. A detailed list and description of TA indicators can be found in Reference [41]. Here, only the most important TA indicators are presented, such as the selected moving averages and oscillators used in our work. These are as follows:  
1. Moving averages: * The simple moving average (SMA) for 5, 10, or 20 days: \[\text{SMA}_{N,C}(k)=\frac{1}{N}[C(k)+C(k-1)+\ldots+C(k-N+1)],\] (1) where \(C(k)\) is the closing price on the \(k\)-th day, \(N\) is the number of days, and \(N\) = 5, 10, or 20. * The exponential moving average (EMA) for 5, 10, or 20 days: \[\text{EMA}_{N,C}(k)=\frac{C(k)+aC(k-1){+}a^{2}C(k-2){+}\ldots+a^{N-1}C(k-N+1)} {1+a+a^{2}+\ldots+a^{N-1}},\] (2) where \(N\) and \(C(k)\) are the same as in Equation (1) and \(a\) is a constant coefficient. 2. Oscillators * The rate of change (ROC) characterizes the rate of price changes over 5, 10, or 20 days: \[\text{ROC}_{N,C}(k)=C(k)/C(k-N).\] (3)
* The relative strength index (RSI) is used to identify whether the market is overbought or oversold. The values are always in the range from 0 to 100. If the RSI is smaller than 30, it is assumed that the market is sold out, while a value larger than 70 means that the market is bought out. However, in the case of strong trends, RSI < 20 signifies a sold-out market (during a bear market) and RSI > 80 indicates a buyout market (during a bull market). The RSI is a measure of the strength of growth movements in relation to downward movements. \[\text{RSI}(k)=100-\left[\frac{100}{1+\frac{\text{EMA}_{N,L}(k)}{\text{EMA}_{N,D}(k)}}\right],\] (4) where: \(U(k)\)--average increase on the \(k\)-th day, and for \(C(k)>C(k-1)\), \(U(k)=C(k)-C(k-1)\), \(D(k)\)--average decrease on the \(k\)-th day, and for \(C(k)<C(k-1)\), \(D(k)=1\,C(k)\)\(-\)\(C(k-1)\), EMA\({}_{N,U}\), EMA\({}_{N,D}\)--exponential moving averages for \(N\) days and for \(U(k)\) or \(D(k)\), respectively. * The stochastic oscillator (\(K\%D\)) determines the relative value of the last closing price in relation to the considered range of price changes in a given period. Oscillator values cover a range from 0 to 100. If \(K\%D\) is over 70, that the closing price is considered to be near the top end of the range of its fluctuations. A \(K\%D\) below 30 indicates that it is close to the lower end of that range. \[K\%D(k)=100\left[\frac{C(k)-L(14)}{H(14)-L(14)}\right],\] (5) where \(L(14)\) and \(H(14)\) are the lowest and highest prices, respectively, over the last 14 days. * The moving average convergence/divergence (MACD) is defined as the difference between the long-term and short-term values of exponential moving averages. This oscillator is used to study buy and sell signals. It is usually compared with its 9-day exponential moving average, which is called the signal line (SL). The intersection of these two signals indicates a buying signal if the MACD line comes from the bottom, and a selling signal if this line is from the top. \[\text{MACD}(k)=\text{EMA}_{12,\text{ }C}\ (k)-\text{EMA}_{26,\text{}C}(k)\] (6) \[\text{SL}(k)=\text{EMA}_{9}(\text{MACD}(k))\] (7)
* Accumulation/distribution (AD) relates to the price and volume and indicates whether the price changes in the stock market appear together with increased accumulation and distribution movements. \[AD(k)=V(k)\frac{C(k)-L(k)-[H(k)-C(k)]}{H(k)-L(k)}\] (8) where \(V(k)\) is a volume, e.g., the total number of shares traded on \(k\)-th day, and \(L(k)\) and \(H(k)\) are the lowest and the highest prices on \(k\)-th day. * The Bollinger oscillator (BOS) informs whether the market is overbought or oversold. It is derived from the Bollinger bands.