What the Smallcap to Sensex Ratio Does Not Tell You

How often does a doctor tell you that he gets half his surgeries wrong?

How many pilots claim to go wrong with their flight take-offs 50% of the time?

How often do sportsmen claim to lose 50% of their matches?

They don't. They can't afford to.

But an investor can.

One of the most peculiar things about investing is that you can be wrong half the time and still do well.

Legendary fund manager, Peter Lynch, famously said...

• In this business, if you're good, you're right six times out of ten. You're never going to be right nine times out of ten.

Investors keen to precisely judge the direction of the markets, assess potential smallcap outperformance versus bluechips or identify stocks that meet quarterly earnings estimates need to understand this.

There is only so much you can get right. The appetite for risk is cyclical and transitory in the stock markets.

It's intuitive to seek high returns from high-risk investments like smallcap stocks. It seems logical to expect volatile stocks to fetch better returns.

But over a period, such strategies prove to be futile. Especially, when the bulk of the returns are lost in a sudden market crash. Investors often get swayed by the greed that smallcap stocks offer.

In a prolonged bull market, smallcap stocks across the board tend to soar. Most well beyond their fundamentals.

The smallcap valuations get frothy over time. Yet, investors pile on to the stocks in the hope that markets will continue to go higher.

Eventually, investors go wrong, markets crash and many lose their shirts.

Now, what draws investors to smallcaps is the idea of fetching bigger returns from relatively smaller amounts of capital. And that is a perfectly good idea when the smallcap valuations are cheap.

But when the stocks of high-risk businesses are valued at a premium, with the assumption of steep earnings growth, they become double edged swords.

A majority of smallcap business lack fortitude, sustainability, and good governance. Hence, they tend to falter on investor expectations. And that is when their valuations come crashing like nine pins.

For instance, consider the smallcap rallies over past two decades...

From 2005 to 2007...

From 2009 to 2010...

From 2015 to 2017...

And from 2022 to 2025.

In each of these cases, the smallcap index outperformed Sensex for few quarters.

But eventually, after every market crash, every Rs 100 invested in the benchmark Sensex offered more returns than every Rs 100 invested in BSE Smallcap index.

The smallcap-to-Sensex ratio is a crucial indicator for Indian investors, acting as a barometer for market sentiment and a guide for portfolio diversification.

This ratio compares the performance of smallcap stocks, which have high growth potential but are also highly volatile, to the stable, large-cap stocks that make up the Sensex.

A rising ratio signals a bull market, where investors are more willing to take on risk and seek higher returns from smaller companies. Conversely, a falling ratio suggests a move to safety, with investors retreating to the relatively low risk large-cap stocks.

This ratio is an essential tool for investors to safely diversify their stock market exposure across market cycles. By monitoring the ratio, investors can make informed decisions about their asset allocation.

When the ratio is low, it may indicate that smallcaps are undervalued, presenting an opportunity for aggressive investors to increase their exposure for potential long-term growth.

When the ratio is high and smallcap valuations seem stretched, it can be a warning sign to rebalance the portfolio by trimming smallcap holdings and increasing exposure to large-caps.

Smallcaps tend to be safer when the smallcap to Sensex ratio goes below the long-term average of 0.46. This is a yardstick we consider safe for recommending smallcaps, even to relatively risk averse investors.

Now, refer to the chart below. Simply plotting the Smallcap to Sensex ratio can give investors a sense of whether the smallcap category is in the buy phase or not.

In the following chart the term 'buy phase' depicts the periods during which good quality smallcap stocks could have been bought at attractive valuations.

Time for Bluechip Revival?

This disciplined approach helps manage risk, as the stability of large-caps can provide a buffer during market downturns, while small-caps offer the potential for disproportionate returns during upcycles.

But there is something that the smallcap to Sensex ratio in India is not telling us.

As few bluechips in India grow significantly larger in size and gain global dominance, the smallcap to Sensex ratio could remain skewed in their favour for years.

For instance the market capitalisation of top 5 stocks in the US was 1.5 times the market capitalisation of US smallcaps way back in the year 2000.

Marketcap of America's Top 5 Stocks to Marketcap of Smallcaps in 2000

In 20 years i.e. in 2025, market capitalisation of top 5 stocks in the US is 4.9 times the market capitalisation of US smallcaps.

Little companies are supposed to earn higher returns over time than bigger entities. But that hasn't been the case in the US for more than two decades.

Since the beginning of 2014, the S&P 500 has grown at an average of 13.2% annually, while the Russell 2000 index of small stocks has gained just 7.2%.

Much of that underperformance comes from underexposure of the Russel index to the market's hottest sector. Technology firms constitute nearly 34% of the total capitalization of the S&P 500, versus less than 13% of total value in the Russell 2000.

Big stocks like Alphabet, Meta, Nvidia and Apple have all the momentum of the artificial-intelligence boom.

Their global dominance has kept the stock prices soaring.

Marketcap of America's Top 5 Stocks to Marketcap of Smallcaps in 2025

So, an investor in the US, waiting for the smallcap to bluechip ratio to turn in former's favour, has waited disproportionately long.

History suggests that if the market's biggest companies do stumble, the little guys might do reasonably well. But here the global weightage of the handful bluechip stocks have made the ratio redundant.

Do you think India's smallcap to Sensex indicator will follow suit?

Let us know your thoughts in the comments.

Warm regards,


Tanushree Banerjee
Editor, StockSelect
Equitymaster Research Private Limited (formerly Equitymaster Agora Research Private Limited) (Research Analyst)