When to switch an index fund: 4 checks for investors

An index fund's only job is to copy its benchmark, but small differences in cost, execution and portfolio management make some funds lag more than others. Investors should check tracking difference, the gap between the index return and the fund return over a period, and tracking error, which measures day-to-day consistency of that gap. A fund that persistently trails its peers for three to five years may have a structural problem, according to Anshi Shrivastava, head of personal finance training at 1 Finance.

Switching solely for a lower expense ratio is often a mistake. The difference between two well-managed funds charging 0.10% and 0.15% annually amounts to roughly Rs 250 a year on a Rs 5 lakh investment. Expense ratio becomes meaningful only when the gap is sustained at 0.3 percentage points or more over a decade or longer. A fund with a slightly higher expense ratio may still be the better choice if it tracks the index more closely.

Asset under management size offers some advantages in trade execution, but does not guarantee good tracking. Large funds with substantial short-term institutional money risk sudden redemptions that force unfavourable sales, increasing tracking slippage. Switching is not inconsistent with passive investing if done because of persistent tracking failure or genuine long-term cost advantage, not a single weak quarter or temporary performance spike.