Common Investing Mistakes: What Should Every Investor Watch Out For?

Should you sell when the market drops fast and your gains start evaporating in real time? The honest answer is almost always no, but I didn’t follow that answer myself the one time it actually mattered.

My portfolio was sitting on gains of nearly ₹1.1 lakh at market open one day. By late morning, more than half of that had disappeared, and I was staring at my Groww app trying to decide whether to sell everything before it got worse. I sold. Not all of it, but enough. I exited my Nifty 50 index fund and a mid-cap fund I’d been holding for about 14 months, booking a loss I didn’t need to book. Within seven weeks, both funds had recovered past the price I’d sold at. That one afternoon taught me more about investing mistakes than three years of reading finance blogs had.

I’m not writing this as someone who’s never messed up. I’m writing it because I have, more than once. HMA Wealth exists precisely to walk Indian investors through moments like that in plain language, without pretending anyone gets it right every single time.

Why Do Almost All New Investors Make the Same Investing Mistakes?

Here’s the pattern I’ve noticed after tracking my own trades for a few years and comparing notes with friends who invest: the mistakes aren’t really about lack of knowledge. Most people know, in theory, that markets go up and down. The mistakes happen because knowing something and behaving calmly about it in the moment are two completely different skills.

A few investing mistakes show up again and again, regardless of income level or education:

• Reacting to short-term price movement instead of sticking to a plan
• Investing without an emergency fund as a cushion
• Picking funds based on last year’s returns
• Ignoring costs like expense ratio and exit load
• Treating insurance policies as investments
• Never reviewing a portfolio once it’s set up
• Not accounting for tax on gains until it’s time to file returns

Each of these looks small on its own. Together, they’re usually the difference between someone who builds real wealth over 15–20 years and someone who stays anxious and mediocre the whole time.

What’s the More Expensive Investing Mistake: Panic-Selling or Never Selling?

Panic-selling gets more attention, but I’d argue the quieter mistake never reviewing or rebalancing often costs more over a decade.

On the panic-selling side: markets correct. That’s not pessimism, it’s just how equity works. The Nifty 50 has been through several sharp drawdowns in the last few years the COVID crash of March 2020, the 2022 correction tied to inflation and rate hikes, and single-session swings like the one I described above. If you sell during the drop and buy back after it recovers, you’ve turned a temporary paper loss into a real, permanent one.

The quieter mistake is what I did for almost two years before that: I set up SIPs systematic investment plans, where a fixed amount is auto-invested into a mutual fund on a set date every month and just never looked again. Two of my four SIPs were running into funds that had changed fund managers and drifted from their original strategy. I only caught it because a friend asked why I was still holding a fund that had underperformed its category average for six straight quarters.

Neither extreme works. You need to look at your portfolio maybe twice a year not daily, not never.

Is Skipping an Emergency Fund the Investing Mistake Behind Every Other Investing Mistake?

I genuinely think it is. Almost every panic-sell I’ve made or watched a friend make traces back to the same root cause: needing cash for something urgent and having nowhere else to pull it from.

A former colleague I’ll call her Priya, since she’d rather not have her name on this had her entire savings in equity mutual funds when her father was hospitalised in late 2022. She had to redeem close to ₹2.4 lakh from funds that were down roughly 9% from her purchase NAV at the time, purely because there was no separate emergency fund to draw on instead. It looked like an investing mistake from the outside, but it wasn’t really about the market at all it was a planning gap wearing a market costume.

If you’re building one, here’s roughly how I’d approach it:

1. Calculate 6 months of essential expenses rent, EMIs, groceries, utilities, insurance premiums. Not lifestyle spending.
2. Keep it separate from your investing account so you’re not mentally tempted to “borrow” from it.
3. Split it between a savings account and a liquid fund or short-term FD, so part of it earns a little more than a plain savings account while staying accessible within a day or two.
4. Top it up before you increase your SIP amounts this order matters more than people think.

Only once that’s actually sitting there, untouched, does the rest of the investing conversation start to make sense.

Why Does Chasing Last Year’s Top Fund Turn Into a Common Investing Mistake?

I did this in 2023. A small-cap fund had returned over 40% the previous year, showed up on every “best funds to invest in” list, and I put a lump sum into it without checking much beyond the one-year return chart.

What I didn’t check properly: how it compared to its category average, its portfolio concentration, and how many of its top holdings overlapped with each other. When small-caps went through a sharp, extended correction starting in the latter part of 2024, that fund fell harder than the broader small-cap category, because it was more concentrated than I’d realised going in.

This is one of the most common investing mistakes because past performance is the easiest number to find and the least useful one to act on alone. A more useful checklist before buying any fund based on its returns:

As always: Mutual Fund investments are subject to market risks; read all scheme-related documents carefully. We’ve gone deeper into comparing mutual fund categories in HMA Wealth’s guide to the different types of mutual funds, which is worth reading before you shortlist anything off a returns chart alone.

Is Ignoring the Expense Ratio a Small Investing Mistake or a Compounding One?

It looks like a small investing mistake. It isn’t.

Expense ratio is the annual fee a mutual fund charges to manage your money, shown as a percentage of your investment. It’s deducted from the fund’s NAV daily, so you never see it as a separate line item which is exactly why it’s easy to ignore.

Here’s a rough comparison that made it click for me:

Illustrative only, assuming identical fund performance before fees actual returns will vary and are never guaranteed.

That gap between direct and regular plans compounds every year you stay invested. I moved my SIPs from regular to direct plans through Groww in 2022, and the process took about 20 minutes check your unit and NAV history for a day or two to confirm the switch went through cleanly. We’ve broken down exactly how expense ratios eat into long-term returns if you want the maths laid out properly.

Why Do So Many Investors Confuse Insurance With Investing?

This is probably the investing mistake I see most often among people in their late 20s and 30s, usually because a relative or agent convinced them a ULIP or endowment plan was “investment plus protection in one.”

The problem is combining the two usually gives you a mediocre version of both. A pure term insurance plan gives you far more life cover per rupee of premium than a ULIP or endowment plan ever will, since none of that premium is quietly diverted into investment components with their own charges. Mixing insurance and investment products tends to mean higher costs, lower liquidity, and lock-in periods running ten years or more.

I bought an endowment policy in 2019 before I understood any of this premium of about ₹22,000 a year, sold to me as “guaranteed returns plus life cover.” Six years in, the actual maturity value works out close to what a savings account would have given me, and I’m still locked in, since surrendering early means losing a chunk of what I’ve already paid. We’ve laid out more of these patterns in HMA Wealth’s piece on common insurance mistakes people make, if any of this sounds familiar.

What Happens When You Skip Diversification Entirely?

Skipping diversification is one of the quieter investing mistakes, because nothing visibly goes wrong until the one stock or sector you’re overweight in has a bad year. Diversification gets treated like a buzzword, but the mechanics are simple: don’t let any single stock, sector, or fund house decide your entire financial outcome.

The version of this mistake I see most often in India isn’t “too few funds” it’s the opposite. People hold 8–10 mutual funds thinking that’s diversification, when half of them are large-cap funds tracking nearly identical index compositions. That’s not diversification. That’s paying multiple expense ratios for the same underlying exposure.

A cleaner approach, and roughly what I run now:

• One core large-cap or index fund as the base
• One flexi-cap or mid-cap fund for a growth tilt
• One small-cap fund, capped at a smaller allocation the volatility here is real, not theoretical
• Debt exposure PPF, EPF, or debt funds sized to your age and how far you are from needing the money
• A small gold allocation, since it often moves differently from equity during stress periods

There’s no single correct number of funds. But if you can’t explain in one sentence why each fund is in your portfolio, that’s usually a sign you added it because of a tip or recommendation, not a strategy.

Which Tax Mistake Catches Almost Every Equity Investor Off Guard?

This is technically a tax question, but it’s also one of the more common investing mistakes I see, simply because people plan the investment and never plan the exit. It isn’t really about the market at all it’s about what happens after you sell, and it surprises people every single tax filing season.

Following changes announced in the Union Budget in July 2024, long-term capital gains (LTCG) on equity mutual funds and stocks held over 12 months are taxed at 12.5%, with gains up to ₹1.25 lakh in a financial year exempt. Short-term gains, on units held under 12 months, are taxed at 20%. These rates have changed before and can change again in a future budget, so check the Income Tax Department’s website for whatever applies in the year you’re actually filing, rather than relying on a number you read somewhere online this article included.

There’s a related trap specifically with debt mutual funds: units purchased on or after 1 April 2023 lost eligibility for long-term capital gains treatment altogether. Gains on those are taxed at your regular income tax slab rate no matter how long you hold them. A lot of people investing in debt funds for “tax efficiency” through 2024 were still working off the older rules without realising they’d changed.

None of this is a reason to avoid equity or debt funds. It’s a reason to actually run the tax math before assuming your “20% return” is what lands in your bank account.

Is “Set It and Forget It” a Smart Strategy or Its Own Investing Mistake?

SIPs are genuinely one of the better habits an Indian retail investor can build. AMFI’s own industry data has shown SIP contributions trending steadily upward over the past several years, which says something about how many people have made this their default approach. But “automate it” and “ignore it forever” aren’t the same instruction, and treating them as identical is its own investing mistake probably the most avoidable one on this list, since it takes no new skill, just a recurring calendar reminder.

What I actually do now, roughly every six months:

1. Check whether each fund is still beating its category average over a rolling 3-year window
2. Confirm my asset allocation equity vs debt vs gold hasn’t drifted too far from what I intended, since a strong equity run can quietly push your risk higher than you meant it to
3. Increase SIP amounts when income goes up, instead of letting the same ₹5,000 SIP run for six years while my salary doubled
4. Re-check that my nominee details are actually correct this one’s boring, and I skipped it for three years without noticing

None of this needs to be complicated. It just needs to actually happen, on a calendar, rather than living as a vague intention.

So What’s the One Investing Mistake I’d Actually Fix First?

Of all the investing mistakes above, if I had to pick one thing to tell a friend who’s just starting out, it wouldn’t be about fund selection or expense ratios, even though both matter. It would be this: build the emergency fund before you build the portfolio, and decide in advance on a calm day, not a red one what you’ll actually do the next time the market drops sharply in an afternoon.

Every other investing mistake on this list gets easier to avoid once that foundation and that decision already exist. The market will hand you another day like 4 June 2024 at some point. The only real question is whether you’ll have already decided how to handle it, or be figuring it out live with your thumb hovering over the sell button.

This article is meant for general education on common investing mistakes and reflects personal experience alongside publicly available information it isn’t personalised financial advice, and HMA Wealth is not a SEBI-registered investment adviser. For decisions specific to your own income, goals, and risk appetite, it’s worth talking to a certified financial planner or a SEBI-registered investment adviser.

FAQs – Common Investing Mistakes