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Rate of return

Rate of return is a mathematics topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Rate of return rather than just read about it. In short: In finance, return is a profit on an investment. It comprises any change in value of the investment, and/or cash flows (or securities, or other investments) which the investor receives from that investment over a specified time period, such as interest payments, coupons, cash dividends and stock dividends.

Key takeaways

  • Rate of return belongs to mathematics; place it in that map before memorising details.
  • Learn the definition first, then one example that makes the definition concrete.
  • Connect Rate of return to a quantity you can measure, compute or draw — that is where exam questions come from.
  • Reproduce the core statement of Rate of return from memory before moving on to harder problems.

Reference excerpt

In finance, return is a profit on an investment. It comprises any change in value of the investment, and/or cash flows (or securities, or other investments) which the investor receives from that investment over a specified time period, such as interest payments, coupons, cash dividends and stock dividends. It may be measured either in absolute terms (e.g., dollars) or as a percentage of the amount invested. The latter is also called the holding period return. A loss instead of a profit is described as a negative return, assuming the amount invested is greater than zero. To compare returns over time periods of different lengths on an equal basis, it is useful to convert each return into a return over a period of time of a standard length. The result of the conversion is called the rate of return. Typically, the period of time is a year, in which case the rate of return is also called the annualized return, and the conversion process, described below, is called annualization. The return on investment (ROI) is return per dollar invested. It is a measure of investment performance, as opposed to size (cf. return on equity, return on assets, return on capital employed).

Calculation The return, or the holding period return, can be calculated over a single period. The single period may last any length of time. The overall period may, however, instead be divided into contiguous subperiods. This means that there is more than one time period, each sub-period beginning at the point in time where the previous one ended. In such a case, where there are multiple contiguous subperiods, the return or the holding period return over the overall period can be calculated by combining the returns within each of the subperiods.

Single-period

Return The direct method to calculate the return or the holding period return R {\displaystyle R} over a single period of any length of time is:

R = V f − V i V i {\displaystyle R={\frac {V_{f}-V_{i}}{V_{i}}}}

where:

V f {\displaystyle V_{f}} = final value, including dividends and interest

V i {\displaystyle V_{i}} = initial value For example, if someone purchases 100 shares at a starting price of 10, the starting value is 100 x 10 = 1,000. If the shareholder then collects 0.50 per share in cash dividends, and the ending share price is 9.80, then at the end the shareholder has 100 x 0.50 = 50 in cash, plus 100 x 9.80 = 980 in shares, totalling a final value of 1,030. The change in value is 1,030 − 1,000 = 30, so the return is 30 1 , 000 = 3 % {\displaystyle {\frac {30}{1,000}}=3\%} .

Negative initial value Return measures the increase in size of an asset or liability or short position. A negative initial value usually occurs for a liability or short position. If the initial value is negative, and the final value is more negative, then the return will be positive. In such a case, the positive return represents a loss rather than a profit. If the initial value is zero, then no return can be calculated.

Currency of measurement The return, or rate of return, depends on the currency of measurement. For example, suppose a US$10,000 (US dollar) cash deposit earns 2% interest over a year, so its value at the end of the year is US$10,200 including interest. The return over the year is 2%, measured in USD. Let us suppose also that the exchange rate to Japanese yen at the start of the year is 120 yen per USD, and 132 yen per USD at the end of the year. The value in yen of one USD has increased by 10% over the period. The deposit is worth 1.2 million yen at the start of the year, and 10,200 x 132 = 1,346,400 yen at the end of the year. The return on the deposit over the year in yen terms is therefore:

1 , 346 , 400 − 1 , 200 , 000 1 , 200 , 000 = 12.2 % {\displaystyle {\frac {1,346,400-1,200,000}{1,200,000}}=12.2\%}

This is the rate of return experienced either by an investor who starts with yen, converts to dollars, invests in the USD deposit, and converts the eventual proceeds back to yen; or for any investor, who wishes to measure the return in Japanese yen terms, for comparison purposes.

Annualization Without any reinvestment, a return R {\displaystyle R} over a period of time t {\displaystyle t} corresponds to a rate of return r {\displaystyle r} :

r = R t {\displaystyle r={\frac {R}{t}}}

For example, let us suppose that US$20,000 is returned on an initial investment of US$100,000. This is a return of US$20,000 divided by US$100,000, which equals 20 percent. The US$20,000 is paid in 5 irregularly-timed installments of US$4,000, with no reinvestment, over a 5-year period, and with no information provided about the timing of the installments. The rate of return is 4,000 / 100,000 = 4% per year. Assuming returns are reinvested however, due to the effect of compounding, the relationship between a rate of return r {\displaystyle r} , and a return R {\displaystyle R} over a length of time t {\displaystyle t} is:

… excerpt ends here. Continue reading the full article.

Worked examples

Example 1 — a first encounter with Rate of return

Start with the simplest possible case. Write down what Rate of return claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In mathematics, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Rate of return before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Rate of return ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Rate of return

In research
Rate of return appears in mathematics research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry
Engineering practice reuses Rate of return in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom
Rate of return is common in secondary-school and first-year university syllabi. It links to neighbouring topics Factor income distribution, Finance theories, Financial markets, so understanding it makes those chapters shorter.
In everyday life
Look for Rate of return outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study Rate of return in 20 minutes

  1. Read the reference excerpt below once, without taking notes.
  2. Close the page and write down what Rate of return means in your own words.
  3. Compare your version with the excerpt and mark what you missed.
  4. Work through the three examples above with pen and paper.
  5. Explain Rate of return out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Rate of return in simple terms?

In finance, return is a profit on an investment. It comprises any change in value of the investment, and/or cash flows (or securities, or other investments) which the investor receives from that investment over a specified time period, such as interest payments, coupons, cash dividends and stock di…

Why does Rate of return matter?

Because it connects several mathematics ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Rate of return?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Rate of return.

Tags

  • Factor income distribution
  • Finance theories
  • Financial markets
  • Financial ratios
  • Investment indicators
  • Mathematical finance
  • Temporal rates

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