Monetary Policy & Stock Prices in Sri Lanka

Part 1: The Mechanics of Monetary Policy and Interest Rates

While fiscal policy is the government's domain, monetary policy is managed by a country's central bank. The CBSL's mandate is to maintain economic and price stability. One of its most powerful tools for achieving this is adjusting key policy interest rates. These are the rates at which commercial banks can borrow from or deposit money with the central bank, which in turn influences the interest rates that banks offer to all of us—on loans, mortgages, and savings accounts.

But how does a change in interest rates affect the stock market? There are several interconnected effects.

To get a comprehensive overview of these mechanisms, please watch the following video. It breaks down the impact from three different perspectives: the consumer, the company, and the investor.

Let's summarize and build on the crucial points from the video.

The Ripple Effect of an Interest Rate Hike

When the CBSL raises interest rates, it sets off a chain reaction:

1. For Consumers: Borrowing becomes more expensive (e.g., higher interest on vehicle leases, personal loans). This reduces disposable income, leading to less consumer spending. Lower spending means lower revenues for many companies, from retailers to manufacturers.

2. For Companies: Businesses that rely on debt to fund operations or expansion face higher interest expenses. This directly reduces their net income. As the video noted, if a company's Price-to-Earnings (P/E) ratio is to stay the same, a lower 'E' (Earnings) must result in a lower 'P' (Price).

3. For Investors (Valuation): This is perhaps the most direct theoretical link. The value of any financial asset, including a stock, is theoretically the present value of all its expected future cash flows. To calculate this "present value," we "discount" those future cash flows using a discount rate. This rate reflects the risk of the investment and the prevailing interest rates.

   When the central bank raises interest rates, the discount rate used to value stocks also goes up. A higher discount rate means future cash flows are worth less in today's terms, thus reducing the stock's calculated intrinsic value.

   Your background in IT might help you think of this as a simple function: Stock_Value = f(Cash_Flows, Discount_Rate). The discount rate is in the denominator of the valuation formula, so increasing it reduces the output (the stock's value).

4. For Investors (Opportunity Cost): When interest rates rise, safer investments like government Treasury bills or bank fixed deposits offer higher returns. This makes them more attractive relative to riskier stocks. An investor might ask, "Why take the risk of stocks for a potential 8% return when I can get a guaranteed 6% from a bond?" This can lead to a shift of capital out of the stock market and into fixed-income assets, putting downward pressure on stock prices.

(This is a good point to take a break. The concepts above cover the fundamental theory of how monetary policy affects the market and should take about 30 minutes to absorb.)

Part 2: Monetary Policy and the Colombo Stock Exchange

The theory we've just discussed is not merely academic; it is observable in the real world, including in Sri Lanka. Let's look at some research specific to the CSE to see how these principles apply locally.

First, let's revisit the research paper from our last lesson, which examined the impact of both fiscal and monetary policy on CSE investors.

The paper confirms that for the CSE:

• An expansionary monetary policy (lower interest rates, more money in circulation) is seen as positive for stock market performance.
• It explicitly mentions the mechanisms: lower interest rates reduce borrowing costs for firms (increasing profits) and also cause a "substitution effect" where investors shift funds from less profitable assets (like low-yield savings accounts) into the stock market.

To see this relationship with more data, let's look at another study that quantifies the impact of several macroeconomic variables on the CSE.

This paper provides clear, quantitative evidence. The correlation analysis shows a significant negative correlation between interest rates and the ASPI. The conclusion reinforces the opportunity cost argument perfectly: when returns on government securities rise, investors shift away from the stock market, causing stock prices to decrease.

A Final Nuance: Theory vs. Reality

It seems straightforward: rate hikes are bad for stocks. However, the real world is more complex. Let's watch the final segment of the first video, which introduces an important counterpoint.

The key insight here is that context is crucial. Central banks don't raise interest rates in a vacuum. They typically do so when the economy is "hot"—meaning economic growth is strong, and inflation is becoming a concern. In such an environment, many companies are experiencing strong revenue and profit growth. This strong business performance can, at least for a time, outweigh the negative mechanical effects of higher interest rates.

Conclusion

In this lesson, we have explored the critical relationship between monetary policy and the stock market, with a specific focus on Sri Lanka.

Key Takeaways:

• Monetary policy, enacted by the Central Bank of Sri Lanka (CBSL), uses tools like interest rates to manage the economy.
• Theoretically, higher interest rates negatively impact stock prices by reducing consumer spending, increasing company borrowing costs, lowering stock valuations (via a higher discount rate), and increasing the opportunity cost of investing in stocks.
• Research on the Colombo Stock Exchange (CSE) confirms this negative relationship, showing that rising interest rates are associated with lower stock returns.
• The economic context matters. Rate hikes often occur during periods of strong economic growth, and the resulting corporate profit growth can sometimes offset the negative pressure from the rate hikes themselves.

Preview of the Next Lesson:

We have now covered the two major domestic policy levers: fiscal and monetary. Next, we will turn our attention to an external factor that is heavily influenced by these policies and global events: the currency exchange rate. Our next lesson will explain how the currency exchange rate (e.g., USD/LKR) impacts the Sri Lankan economy and the stock market.