SIPs, Lumpsum and Market Falls
Why SIPs help your behaviour more than your returns, when a lumpsum makes sense, and why a falling market is not automatically bad news for a long-term investor.
- ·How an SIP controls behaviour
- ·Rupee-cost averaging, honestly
- ·When lumpsum makes sense
- ·Why falls help accumulators
- ·Staying invested through crashes
- ·Real NIFTY fall examples
In March 2020, the market fell off a cliff. NIFTY dropped roughly 38% in a few weeks as the COVID fear spread. Meera, 31, had a SIP of Rs 10,000 a month going into an index fund. Her friend Ravi had the very same SIP. When the screen turned deep red, Ravi panicked, cancelled his SIP, and pulled his money out to "wait for things to settle". Meera did nothing. Her SIP kept buying, automatically, every month, right through the worst of it. A year later the market had recovered and pushed higher. Meera's boring, automatic buying through the fall had quietly scooped up units at prices Ravi was too scared to touch. Same fund, same start, very different ending. The difference was not skill. It was behaviour.
A SIP, a systematic investment plan, is simply a standing instruction to invest a fixed amount every month into a fund, automatically. Most beginners think its magic is about returns. It is not, really. Its biggest gift is what it does to you.
What a SIP actually does for you
Every month, on the same date, the same rupees go in, whether the market is cheerful or terrifying. You never have to ask "is now a good time?" The machine answers for you. That one feature removes the single decision that wrecks most investors: timing.
Timing feels clever and is mostly a trap. Wait for a dip and you often watch prices run away. Buy when you feel brave and you usually feel brave near the top. A SIP sidesteps all of it. It keeps you buying in fear, in boredom, in greed, all the same. You are not smarter than the market with a SIP. You are just more consistent than your own moods.
A SIP's real value is behavioural, not magical. It removes the timing decision and keeps you buying through fear, when most people freeze or flee. It manages your behaviour; it does not promise better returns.
Rupee-cost averaging, honestly
Here is the part that gets oversold, so let us be straight about it. Because you invest a fixed rupee amount and the price per unit moves around, you automatically buy more units when prices are low and fewer when prices are high. Over a bumpy ride, your average cost per unit ends up a little below the simple average price. That is rupee-cost averaging. It is real, but it is a side effect, not a money machine.
The honest catch: this only helps if the market is bumpy and then recovers. If prices simply rise in a straight line, a single lumpsum at the start would have beaten the SIP, because your money would have been working sooner. Averaging shines in exactly the kind of scary, falling-then-rising market that frightens people out. It is a tool for managing timing risk and your nerves, not for maximising returns.
A SIP through a dip: the numbers
Say you put in Rs 10,000 every month for six months while the price per unit (the NAV) dips and then climbs back to where it began.
| Month | Price per unit | Amount invested | Units bought |
|---|---|---|---|
| 1 | Rs 100 | Rs 10,000 | 100.00 |
| 2 | Rs 90 | Rs 10,000 | 111.11 |
| 3 | Rs 70 | Rs 10,000 | 142.86 |
| 4 | Rs 60 | Rs 10,000 | 166.67 |
| 5 | Rs 75 | Rs 10,000 | 133.33 |
| 6 | Rs 100 | Rs 10,000 | 100.00 |
| Total | - | Rs 60,000 | 753.97 |
Your average cost works out to Rs 60,000 / 753.97, about Rs 79.58 per unit, well below the Rs 100 you started and ended at. With the price back at Rs 100, your 753.97 units are worth about Rs 75,397, a gain of roughly Rs 15,397, even though the price finished exactly where it began. The dip did that. The cheap units in months 3 and 4 carried the result. A lumpsum of Rs 60,000 at the start, at Rs 100, would have bought 600 units and ended flat at Rs 60,000. This is an illustration, not a forecast.
When a lumpsum makes sense
A lumpsum is putting a large amount in at one go. It is the right tool in a specific situation: money you already have (a bonus, a maturity, the sale of a property), a long horizon of many years, and a temperament that can sit still if the market drops the very next week.
The logic is simple. Markets rise more often than they fall, so money invested earlier usually spends more time compounding. On average, putting it all in tends to beat dribbling it in, but only if you can hold through an early fall. That "if" is the whole problem. A lumpsum invested just before a 2020-style crash feels awful, and many people sell at the bottom and never come back. So a lumpsum suits money that is genuinely long-term and a person who can stomach a fall right after investing. If either of those is shaky, spreading it into a SIP is the kinder, safer choice.
Two classic errors. The first is stopping your SIP in a crash, which cancels your buying at the exact moment units are cheapest, the opposite of what you would do on purpose. The second is lump-summing scared money, money you cannot bear to watch fall or might need soon. If a fall the next morning would force you to sell or rob your sleep, that money should not go in all at once, and arguably should not go into the market yet at all.
Why a falling market is not the enemy
If you are still buying for years to come, you are a net buyer. And a net buyer should want low prices. A fall is a discount on the units you were going to buy anyway. The accumulator who panics in a crash is like a shopper who runs out of the store the moment everything goes on sale.
The only investors who should truly fear a fall are those who need to sell soon, a retiree drawing down, or someone whose goal is months away. For everyone with a long runway ahead, a deep, scary fall that later recovers is one of the best things that can happen during the buying years. The 2020 fall proved it: the SIPs that kept running through March 2020 bought their cheapest units of the decade, and those units did the heavy lifting in the recovery.
How the four user types read this
A SIP is mostly an investor's tool. It does not translate cleanly to the faster corners of the market.
| User type | Does a SIP fit? | Why |
|---|---|---|
| Long-term investor | Yes, a core habit | Fixed monthly buying suits a multi-year accumulate-and-hold plan |
| Active trader | No, a different game | Trading lives on entries, exits and stops, not steady monthly buying |
| F&O beginner | No | Derivatives expire and use leverage; you cannot safely "average into" a wasting, leveraged bet |
| Option seller | No | A margin-and-rules income strategy, not a buy-and-hold accumulation |
When this fails
A SIP is a behaviour tool, not a shield. It has clear limits.
It assumes the thing you are buying recovers. A SIP into a broad index has history on its side; over long periods it has come back and gone higher. A SIP into a single falling stock has no such guarantee. If that one company keeps sinking, you are simply averaging down towards zero, buying more of a losing story. Rupee-cost averaging rescues a diversified basket far more reliably than it rescues one bad pick.
It also fails if you need the money during the fall. The whole benefit assumes you can keep holding and keep buying. If your horizon is short, or you have no emergency fund and are forced to sell in the crash to pay bills, the discount turns into a real, locked-in loss. A SIP does not prevent losses; it only helps if you stay invested. The moment you sell in fear, every behavioural advantage is gone. And it quietly depends on your cash flow: a SIP you cannot afford to keep funding through a downturn is the one most likely to be cancelled at the worst time. None of this is personalised advice; it is an education example, and your own numbers and goals decide what fits you.
Quick self-check
1. What is the main benefit of a SIP, returns or behaviour?
Behaviour. A SIP removes the timing decision and keeps you buying automatically through fear and boredom. It manages your moods; it does not promise higher returns.
2. In rupee-cost averaging, why do you end up buying more units when prices are low?
Because you invest a fixed rupee amount each month while the price per unit moves. The same Rs 10,000 buys more units at a low price and fewer at a high price, so your average cost lands a little below the average price.
3. When does a lumpsum make more sense than a SIP?
When the money is already in hand, the horizon is long, and you can sit still if the market falls right after you invest. Markets rise more often than they fall, so investing earlier tends to win, but only if you can hold through an early drop.
4. Why is a falling market not automatically bad for a long-term accumulator?
Because someone still buying for years ahead is a net buyer, and a fall is a discount on the units they were going to buy anyway. Only investors who must sell soon should fear a fall.
5. Give one situation where a SIP does not protect you.
A SIP into a single stock that keeps falling and never recovers, or any case where you need the money during the crash and are forced to sell at the bottom. A SIP manages behaviour; it does not prevent losses once you sell in fear.