How variation in interest rates alters the returns in debt funds

Every time there is a fall in the net asset value (NAV) of debt funds, there is renewed panic. The simple question in the investor's mind is: if there is no default and the fund is receiving its interest income, how and why should the NAV fall? A drop in the NAV of a debt fund can trigger alarm and lead to a precipitous closure for some, as happened in 2008. The market risks in mutual funds are not widely understood, leading to accusations that these should have been avoided somehow.

Investing in a debt fund is quite different from doing so in a bond or fixed deposit. In the case of a fixed deposit, the investor agrees to an unrealistic freeze in rupee return, in exchange for convenience and simplicity. The government no longer determines interest rates in our economy, nor are they dictated by powerful institutions. We have transitioned to a market for interest rates, and this market enables money to be lent and borrowed based on the needs and views of a large number of participants.

In such a market place, there are only prices and clearing. There is no right and wrong. If a borrower is willing to pay 8% for a year, and a lender agrees to it, the exchange of money is cleared at the agreed rate. The borrower needs the money; the lender has the money. The market just brings them together and enables the clearing. Alternatively, the borrower might be in the market today believing that the rates are set to rise and, therefore, wanting to borrow today; the lender might be in the market with a view that rates are set to fall and, therefore, eager to lend. We will never know the motivations, nor will we be able to identify why rates move up or down. At the end of the day, as long as everyone keeps their promise, we have a market where rates are determined efficiently and fairly.

When an investor chooses a bank deposit, he does not select the market. This is the reason he settles for a 4% rate on his savings bank account, while the bank itself would be lending its surplus balance for 8% in the call market. The bank is in the market for overnight funds, lending and borrowing as needed, while the saving bank depositor is standing out, content with a fixed rate. The market does not matter to this simple investor. He may get a lower or a higher rate. He is happy with a fixed rate and unwilling to look beyond.

What happens when such an investor chooses a debt fund? He simply steps into the market place for borrowing and lending. In this market, the rates change dynamically based on demand and supply and the views of various players. What is in the market is what he gets. This investor makes 9% on his liquid fund, when the money market rates are high; he makes 4% on his gilt funds, when the interest rates have risen; he makes 12% on his income fund, when credit spreads fall; and he makes 16% on his short-term fund, when rates correct sharply. Mutual funds are subject to market risk.

A debt fund also pools in money and creates a portfolio much like an equity fund, except that it buys debt securities issued by governments, banks and companies. If a five-year bond is issued at an interest of 10%, and the fund buys it, it earns this interest just like any other investor. However, since a debt fund is an open-ended product in which investors can come and go as they please, it accounts for the interest income on a daily basis. Therefore, the NAV of all debt funds will hold a component that represents this steady accrual income.