- What Actually Happens When You Buy Each One
- What the Expense Ratio Doesn't Tell You
- The Premium/Discount Problem
- SIP Reality: The Factor Most Comparisons Skip
- Who Should Pick What
- The Bottom Line
ETFs tracking the Nifty 50 can have an expense ratio as low as 0.02%. Index Funds in direct plans charge 0.10–0.30%. On paper, ETFs look cheaper. In practice, that gap can disappear or reverse. This blog covers every real difference between ETFs and Index Funds, including the ones most comparisons skip.
What Actually Happens When You Buy Each One
Both instruments track the same index. The difference is in how you access them.
An ETF (Exchange Traded Fund) trades on the stock exchange like a share. For a retail investor, that usually means a demat and trading account. The price moves throughout the day, and you can buy or sell at the market price or with a limit order.
An Index Fund is a mutual fund. In regular folio mode, no demat account is needed. You invest through an AMC or mutual fund platform, and units are allotted at the applicable end-of-day NAV, subject to cut-off-time and money-realisation rules.
| ETF | Index Fund | |
| Account needed | Demat + Trading | No demat/trading account needed in folio mode |
| Pricing | Live changes every second | End-of-day NAV |
| Minimum investment | 1 unit (varies by ETF) | ₹100 on most platforms |
| Who manages it | AMC, listed on NSE/BSE | AMC, direct with the fund house |
Passive investing now commands approximately 17% of total mutual fund AUM in India, ₹13.67 lakh crore as of October 2025. Both ETFs and Index Funds are driving that growth.
What the Expense Ratio Doesn't Tell You
Three factors determine your actual cost of owning either instrument.
1. ETF expense ratio is usually lower. The gap between 0.02% (ETF) and 0.10–0.30% (Index Fund direct plan) is real. Over a large corpus and long holding period, this compounds meaningfully in the ETF's favour.
2. But ETFs carry trading costs the expense ratio doesn't capture. Every time you buy or sell an ETF, you pay brokerage, Securities Transaction Tax (STT), and the bid-ask spread. The bid-ask spread is the gap between what a buyer is willing to pay and what a seller is willing to accept. In real terms: you might buy an ETF unit at ₹198 and, if you sell immediately, only receive ₹196, even if the Nifty 50 value hasn't moved. This spread is tight in high-volume ETFs but can be noticeably wider in low-volume ones.
3. The Regular Plan trap. Many investors unknowingly invest in a Regular Plan Index Fund through a distributor and pay an expense ratio of 0.40–0.60%. For example, ICICI Prudential Nifty 50 Index Fund shows 0.41% for the Regular plan versus 0.20% for the Direct plan.
The Premium/Discount Problem
An ETF has two prices at any moment: its NAV (what the underlying stocks are actually worth) and its market price (what people are trading it at on the exchange). These are not always the same.
When market price > NAV → ETF is trading at a premium. You are overpaying. When market price < NAV → ETF is trading at a discount. You are getting it cheaper than its actual value.
To check fair value in real time, look at the iNAV (Indicative NAV), updated throughout the trading day on NSE and AMC websites. If the ETF market price is significantly above iNAV, wait or use a limit order.
This gap matters more for smaller or sectoral ETFs with thin trading volumes. For large, liquid ETFs like Nippon Nifty BeES or SBI Nifty 50 ETF, the premium/discount is usually negligible.
SIP Reality: The Factor Most Comparisons Skip
For a salaried investor doing a monthly SIP of ₹5,000, the operational difference matters more than the 0.08% expense ratio gap.
Index Fund SIP is fully automated, set the date, set the amount, done. Executed at end-of-day NAV with no action required.
ETF investing can also be made regular, but automation is broker-dependent and execution still happens on the exchange at the prevailing market price or your limit price.
For most retail investors building wealth through monthly contributions, Index Fund wins on simplicity alone.
Who Should Pick What
| Choose ETF if… | Choose Index Fund if… |
| You already have a Demat account | You don't have a Demat account |
| You are investing a lump sum | You are doing a monthly SIP |
| You are comfortable with limit orders | You want fully automated investing |
| You want the lowest possible expense ratio | You want simplicity and zero execution friction |
| Your corpus is large enough for spread costs to matter less | You are starting small (₹500–₹5,000/month) |
The Bottom Line
Both ETFs and Index Funds track the same index and carry the same tax treatment. The difference is entirely in execution. For a first-time investor building wealth through monthly SIPs, a Direct Plan Index Fund is simpler and harder to get wrong. For an investor with a Demat account, a large lump sum, and comfort placing limit orders, a liquid Nifty ETF can be marginally cheaper.
The two mistakes worth avoiding: buying an ETF without checking its daily volume and iNAV, and buying an Index Fund on a Regular Plan. Both cost you more than they should.