RSI stands for the relative strength index. It is a key tool used in technical analysis, assessing the momentum of assets to gauge whether they are in overbought or oversold territory.

In trading, a rollover is a process of keeping a position open beyond its expiry.

Return on capital employed, or ROCE is a long-term profitability ratio that measures how effectively a company uses its capital. The metric tells you the profit generated by each dollar (or other units of currency) employed.

The Regulatory News Service, or RNS, is responsible for disseminating regulatory and non-regulatory information on behalf of UK businesses and publicly listed companies. Operating as part of the London Stock Exchange (LSE), the RNS provides businesses with information that can help them to comply with their disclosure obligations.

A ratio spread is a strategy used in options trading, in which a trader will hold an unequal number of buy and sell options positions on a single underlying asset at once.

Rate of return (ROR) is the loss or gain of an investment over a certain period, expressed as a percentage of the initial cost of the investment. A positive ROR means the position has made a profit, while a negative ROR means a loss. You will have a rate of return on any investment you make.

Random walk theory is a financial model that assumes that the stock market moves in a completely unpredictable way. The hypothesis suggests that the future price of each stock is independent of its own historical movement and the price of other securities.

A rally is a period in which the price of an asset, market or index sees sustained upward momentum. Typically, a rally will arrive after a period in which prices have been flat or in a decline.

Revaluation reserve is when a company creates an item on its balance sheet for maintaining a reserve account tied to particular assets. 

A revenue deficit is when the realized net income is less than the projected net income.

Realized yield is the real return gained during the holding period for an investment. It includes dividends, interest payments, and so on.

The ratchet effect is a theory that once prices rise as an answer to a very high demand, they do not necessarily fall when that demand declines.

Rebate is the portion of interest or dividends gained by the owner of a stock paid by a short seller of the stock. 

Rho is the rate at which the price of a derivative shifts relative to a change in the risk-free rate of interest. 

A retainer fee is an amount paid upfront to secure the services of financial professional. 

A ring-fence is a virtual barrier that separates individual's or company's financial assets from the rest.

Repatriable is the ability to move liquid financial assets from a foreign country to investor's country.

Revolving door is the movement of high-level employees from public sector to private sector jobs, and vice versa. 

Real option is a choice available to the managers of a company regarding business investment opportunities.

Real rate of return is the annual percentage return on an investment. It is adjusted for changes due to inflation or other factors.