New Delhi, June 11 -- The term "fixed income" sounds reassuring-evoking stability, predictable returns, and minimal risk. But in today's market, this label can be misleading. From wild price swings to rate-driven gains and losses, fixed income is no longer as 'fixed' as it once was.

The roots of what we now call fixed income go back at least 250 years, when the British government issued "Consols"-a type of perpetual bond used to finance wars. These bonds had no maturity date and paid fixed coupons indefinitely, until redeemed by the government.

The term gained prominence with the advent of modern portfolio theory in the 1950s, when economists like Harry Markowitz developed frameworks around diversification and risk. These theories clear...