Market liquidityIn business, economics or investment, market liquidity is a market's feature whereby an individual or firm can quickly purchase or sell an asset without causing a drastic change in the asset's price. Liquidity involves the trade-off between the price at which an asset can be sold, and how quickly it can be sold. In a liquid market, the trade-off is mild: one can sell quickly without having to accept a significantly lower price. In a relatively illiquid market, an asset must be discounted in order to sell quickly.
Stock market indexIn finance, a stock index, or stock market index, is an index that measures the performance of a stock market, or of a subset of a stock market. It helps investors compare current stock price levels with past prices to calculate market performance. Two of the primary criteria of an index are that it is investable and transparent: The methods of its construction are specified. Investors may be able to invest in a stock market index by buying an index fund, which is structured as either a mutual fund or an exchange-traded fund, and "track" an index.
Insider tradingInsider trading is the trading of a public company's stock or other securities (such as bonds or stock options) based on material, nonpublic information about the company. In various countries, some kinds of trading based on insider information are illegal. This is because it is seen as unfair to other investors who do not have access to the information, as the investor with insider information could potentially make larger profits than a typical investor could make.
High-frequency tradingHigh-frequency trading (HFT) is a type of algorithmic trading in finance characterized by high speeds, high turnover rates, and high order-to-trade ratios that leverages high-frequency financial data and electronic trading tools. While there is no single definition of HFT, among its key attributes are highly sophisticated algorithms, co-location, and very short-term investment horizons in trading securities. HFT uses proprietary trading strategies carried out by computers to move in and out of positions in seconds or fractions of a second.
Adverse selectionIn economics, insurance, and risk management, adverse selection is a market situation where buyers and sellers have different information. The result is the unequal distribution of benefits to both parties, with the party having the key information benefiting more. In an ideal world, buyers should pay a price which reflects their willingness to pay and the value to them of the product or service, and sellers should sell at a price which reflects the quality of their goods and services.
Liquidity trapA liquidity trap is a situation, described in Keynesian economics, in which, "after the rate of interest has fallen to a certain level, liquidity preference may become virtually absolute in the sense that almost everyone prefers holding cash rather than holding a debt (financial instrument) which yields so low a rate of interest." A liquidity trap is caused when people hold cash because they expect an adverse event such as deflation, insufficient aggregate demand, or war.
Dark poolIn finance, a dark pool (also black pool) is a private forum (alternative trading system or ATS) for trading securities, derivatives, and other financial instruments. Liquidity on these markets is called dark pool liquidity. The bulk of dark pool trades represent large trades by financial institutions that are offered away from public exchanges like the New York Stock Exchange and the NASDAQ, so that such trades remain confidential and outside the purview of the general investing public.
Measure (mathematics)In mathematics, the concept of a measure is a generalization and formalization of geometrical measures (length, area, volume) and other common notions, such as magnitude, mass, and probability of events. These seemingly distinct concepts have many similarities and can often be treated together in a single mathematical context. Measures are foundational in probability theory, integration theory, and can be generalized to assume negative values, as with electrical charge.
High frequencyHigh frequency (HF) is the ITU designation for the range of radio frequency electromagnetic waves (radio waves) between 3 and 30 megahertz (MHz). It is also known as the decameter band or decameter wave as its wavelengths range from one to ten decameters (ten to one hundred meters). Frequencies immediately below HF are denoted medium frequency (MF), while the next band of higher frequencies is known as the very high frequency (VHF) band. The HF band is a major part of the shortwave band of frequencies, so communication at these frequencies is often called shortwave radio.
Outer measureIn the mathematical field of measure theory, an outer measure or exterior measure is a function defined on all subsets of a given set with values in the extended real numbers satisfying some additional technical conditions. The theory of outer measures was first introduced by Constantin Carathéodory to provide an abstract basis for the theory of measurable sets and countably additive measures.
