Much effort has gone into the study of financial markets and how prices vary with time. Charles Dow, one of the founders of Dow Jones & Company and The Wall Street Journal, enunciated a set of ideas on the subject which are now called Dow Theory. Modigiliani's books: https://www.amazon.com/gp/search?ie=UTF8&tag=tra0c7-20&linkCode=ur2&linkId=a3df9c167e859249c471fa08d652e1d7&camp=1789&creative=9325&index=books&keywords=franco%20modigliani
This is the basis of the so-called technical analysis method of attempting to predict future changes. One of the tenets of "technical analysis" is that market trends give an indication of the future, at least in the short term. The claims of the technical analysts are disputed by many academics, who claim that the evidence points rather to the random walk hypothesis, which states that the next change is not correlated to the last change. The role of human psychology in price variations also plays a significant factor. Large amounts of volatility often indicate the presence of strong emotional factors playing into the price. Fear can cause excessive drops in price and greed can create bubbles. In recent years the rise of algorithmic and high-frequency program trading has seen the adoption of momentum, ultra-short term moving average and other similar strategies which are based on technical as opposed to fundamental or theoretical concepts of market Behaviour.
The scale of changes in price over some unit of time is called the volatility. It was discovered by Benoît Mandelbrot that changes in prices do not follow a Gaussian distribution, but are rather modeled better by Lévy stable distributions. The scale of change, or volatility, depends on the length of the time unit to a power a bit more than 1/2. Large changes up or down are more likely than what one would calculate using a Gaussian distribution with an estimated standard deviation.
The bond market (also debt market or credit market) is a financial market where participants can issue new debt, known as the primary market, or buy and sell debt securities, known as the secondary market. This is usually in the form of bonds, but it may include notes, bills, and so on. The primary goal of the bond market is to provide a mechanism for long term funding of public and private expenditures. Traditionally, the bond market was largely dominated by the United States, but today the US is about 44% of the market. As of 2009, the size of the worldwide bond market (total debt outstanding) is an estimated $82.2 trillion, of which the size of the outstanding U.S. bond market debt was $31.2 trillion according to Bank for International Settlements (BIS), or alternatively $35.2 trillion as of Q2 2011 according to Securities Industry and Financial Markets Association (SIFMA).
Nearly all of the $822 billion average daily trading volume in the U.S. bond market takes place between broker-dealers and large institutions in a decentralized, over-the-counter (OTC) market. However, a small number of bonds, primarily corporate, are listed on exchanges.
References to the "bond market" usually refer to the government bond market, because of its size, liquidity, relative lack of credit risk and, therefore, sensitivity to interest rates. Because of the inverse relationship between bond valuation and interest rates, the bond market is often used to indicate changes in interest rates or the shape of the yield curve. The yield curve is the measure of "cost of funding".