Glossary · Investing Basics
Compound Interest
Interest calculated on both the initial principal and the accumulated interest from previous periods. The foundation of long-term wealth creation is widely regarded as one of the most powerful forces in investing.
01—What is Compound Interest?
The definition — and what it means in practice.
Compound interest is interest calculated on both the original principal and the interest already earned in earlier periods. Instead of only earning on your starting amount, each period’s interest is added to the balance, so the next period’s interest is computed on a larger base. The effect becomes stronger the longer the money stays invested and the more frequently compounding occurs.
Compound interest matters because it explains why time and consistency can be more important than trying to time markets. In practice, compounding works whenever your returns are reinvested, such as interest credited to a deposit, profit paid into a fund, or dividends that you use to buy more shares. It also works against you on borrowing, where unpaid charges can increase what you owe.
If Rs 100 earns 10% and you reinvest it, you have Rs 110, then next period you earn 10% on Rs 110 (Rs 11), not Rs 100.
Future Value = Principal × (1 + r)^n
r = periodic interest/return rate; n = number of compounding periods.
- Compounding means you earn returns on past returns, not just on the original amount.
- Time is the biggest driver: small rates can grow meaningfully over many periods.
- Reinvesting dividends or profits is how compounding shows up in many investments.
- Compounding can be positive (wealth growth) or negative (debt snowballing).
02—How compound interest works on the PSX
The Pakistan-specific rules, conventions, and numbers.
On the Pakistan Stock Exchange (PSX), returns are not labelled as “interest”, but the compounding idea still applies when gains are reinvested. If you receive a cash dividend and use it to buy additional shares (subject to board lot rules), future dividends and price moves apply to a larger holding. The same logic applies when you reinvest proceeds from a sale rather than leaving cash idle.
PSX dividends are typically announced as a percentage of face value; many listed shares have a Rs 10 face value, so a “100%” dividend equals Rs 10 per share before withholding tax. In Pakistan, withholding tax on cash dividends is 15% for income-tax filers and 30% for non-filers, so the amount you can reinvest (and compound) is the net dividend. Over time, consistent reinvestment can materially change your total shares held.
03—Common misconceptions
Where investors most often get this wrong.
Compound interest only applies to bank deposits, not shares.
Shares do not pay “interest”, but reinvested dividends and reinvested gains can create the same compounding effect over time.
Compounding guarantees profits if I wait long enough.
Compounding magnifies whatever returns you actually earn. If returns are negative or dividends are not reinvested, compounding will not deliver a guaranteed outcome.
Higher compounding frequency always means higher returns.
Frequency matters, but the rate and the time horizon matter more. Fees, taxes, and periods of low or negative returns can outweigh frequency effects.
04—Using compound interest on BSL
Where this term shows up across the platform — with live data.
- See dividend-focused opportunities on Highest Dividend Yield.
- Check important dividend timelines using Ex Dates.
- Explore listed shares you can reinvest into via Stocks.
- Compare companies by sectors on Sectors.
05—Frequently asked questions
What investors ask about compound interest on the PSX.
Frequently Asked Questions
It works whenever returns are added back to your balance so future returns are earned on a larger base. Examples include reinvested profits in funds, interest credited to savings products, or dividends reinvested into more shares.
The concept is the same, but the source differs. On the PSX, compounding typically comes from reinvesting cash dividends or reinvesting realised gains, rather than a fixed interest payment.
Yes. Cash dividends paid by listed companies are subject to withholding tax in Pakistan, so the net amount available to reinvest is lower, which can reduce long-run compounding compared with gross reinvestment.
Simple interest is calculated only on the original principal. Compound interest is calculated on the principal plus previously earned interest, so the growth rate accelerates over time if returns are reinvested.
Compounding itself is a method, not a direction. It can work against you when charges or borrowing costs are added to a balance, increasing the amount on which future charges are calculated.
06—Related terms
Keep building the picture.
The cost of borrowing money, set by the State Bank of Pakistan through the policy rate. Rising interest rates generally weigh on equity valuations by increasing the discount rate applied to future earnings.
Interest that has been earned on a bond or fixed-income security but has not yet been received or paid. When a bond is bought between coupon payment dates, the buyer typically pays the seller the accrued interest for the period already elapsed.
A portion of a company's profits distributed to shareholders. Can be in the form of cash, bonus shares, or a combination of both.
A direct payment made by a company to its shareholders, usually from profits, expressed as a rupee amount per share. Subject to withholding tax in Pakistan.
Annual dividend per share divided by the current share price, expressed as a percentage. A useful metric for income-focused investors is to compare dividend yields across different stocks.
A contract that guarantees a series of regular payments to an individual in exchange for a lump sum investment, typically used for retirement income purposes.
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