"Just buy an index fund" and "just buy a Nifty ETF" get thrown around as if they're the same advice. They're close cousins, not twins. If you've ever wondered why your ETF units aren't exactly matching the index price you saw on Google, or why your SIP into an ETF keeps failing, this is the article for you.
| Index Fund | ETF | |
|---|---|---|
| Where you buy it | Directly from AMC / distributor / app | Stock exchange, via demat + trading account |
| SIP friendly | Yes — auto-debit monthly, no manual action | Manual buying each time (some brokers offer ETF SIPs, with limits) |
| Price you get | End-of-day NAV, always accurate | Live market price — can trade at a premium/discount to NAV |
| Expense ratio | Slightly higher, still low | Usually marginally lower |
| Minimum investment | As low as ₹100–500 | Cost of 1 unit (varies, often ₹200–3,000+) |
| Extra accounts needed | None | Demat + trading account (with charges) |
| Liquidity risk | None — redeem at NAV any working day | Depends on trading volume of that ETF |
An index fund always transacts at its actual NAV — no ambiguity. An ETF trades on the exchange like a stock, so its price depends on who's buying and selling right now. For popular, high-volume ETFs this gap (called the bid-ask spread) is tiny. But for lower-volume ETFs, you can end up buying above NAV or selling below it — a real cost that doesn't show up in the expense ratio and is easy to miss if you're not watching closely.
The single biggest reason index funds dominate for retail SIP investors in India is convenience. You set up an auto-debit once, and money leaves your bank account and buys units automatically every month — no logging in, no checking prices, no manual clicks. With an ETF, unless your broker specifically supports ETF SIPs (and many have quantity or timing limits), you're placing a trade yourself each time. Miss a month because you forgot to log in, and your compounding quietly takes a hit.
| Check | Why it matters |
|---|---|
| Tracking error | Lower means the fund/ETF is closely following its index — check the fact sheet |
| Expense ratio | Compare like-for-like on the same index, not across different indices |
| Trading volume (for ETFs) | Low volume = wider spread = hidden cost |
| AUM size | Larger, well-established funds tend to track more efficiently |
For most Indian investors building long-term wealth through disciplined monthly SIPs, the index fund wins on pure convenience — the marginal cost saving of an ETF rarely offsets the friction of manual buying, demat charges, and spread risk. ETFs earn their place for lump-sum investors and those already comfortable trading on an exchange. Either way, the index you choose to track matters more than the wrapper — that decision deserves as much thought as the fund-vs-ETF question itself. For the bigger-picture question of stepping beyond safety-first instruments, our FD vs mutual fund comparison covers why passive equity exposure matters at all.