Comparative Volatility Dynamics of Indian SME and ESG Indices: Persistence, Asymmetry, and Investment Implications

In the world of investing, money moves through markets much like water flows through rivers, sometimes calm and predictable, other times turbulent and unpredictable. For decades, investors have relied on broad measures to gauge the health of the economy, but a newer trend has emerged where people look at specific themes, such as companies that prioritize environmental and social responsibility, or small businesses that drive local employment. A central question in finance is how these different types of investments behave when the market gets rough. Do they calm down together, or does one panic while the other stays steady? To answer this, researchers look at volatility, a term that simply describes how wildly prices swing up and down. They also examine whether bad news causes a bigger shock than good news, and whether a sudden jolt in the market fades away quickly or lingers for a long time. Understanding these patterns helps investors decide where to put their money, especially during uncertain times like a global pandemic.

A team of researchers from Dr. Bhim Rao Ambedkar College in New Delhi set out to compare two very different investment themes in India: the NSE ESG Index, which tracks large, reputable companies known for strong environmental and governance practices, and the NSE SME Emerge Index, which follows small and medium-sized businesses aiming for rapid growth. The study covered eight years of daily market data, splitting the timeline into three distinct eras: the years before the global pandemic, the years during and after the pandemic, and the entire period combined. The goal was to see if the common belief that small businesses are inherently riskier and more volatile than large, responsible companies held true, and to determine how these two groups reacted to the massive economic shock of the pandemic.

The researchers began by looking at the basic performance of these indices. They found that over the entire eight-year period, the average daily returns for both the small business index and the ESG index were surprisingly similar. However, a closer look at the post-pandemic years revealed a shift: the small business index actually delivered higher average returns than its counterpart during that specific recovery period. When measuring risk by looking at how much the prices fluctuated, the study found no major difference between the two groups over the long term. This finding challenges the widespread perception that investing in small companies is significantly more dangerous than investing in large, established ones. In fact, the data suggested that the risk profiles of these two very different types of companies were quite comparable.

To understand how these markets behaved when things went wrong, the team used advanced statistical tools to model the "memory" of the market. They were looking for a specific pattern: if the market had a bad day, would that fear linger into the next day, or would it disappear quickly? The analysis showed that for both the small business index and the ESG index, volatility has a long memory. When a shock occurs, the market does not calm down immediately; instead, the effects of that shock fade away very slowly. This means that once volatility starts, it tends to stick around for a while before returning to normal. The researchers also tested whether the market reacted differently to bad news compared to good news, a phenomenon known as asymmetry. Here, the two indices behaved very differently. The ESG index showed no such difference; it reacted to positive and negative news in the same way. The small business index, however, reacted much more strongly to bad news than to good news, showing a clear asymmetry in its behavior.

Another key discovery was how these indices were connected to the broader Indian stock market. The returns of the ESG index were closely tied to the movements of the larger market, meaning if the big market moved, the ESG index moved with it. In contrast, the small business index seemed to move on its own, largely ignoring the ups and downs of the broader market and instead following its own internal rhythm. This independence suggests that small businesses could be a valuable addition to an investment portfolio, as they do not necessarily rise and fall in lockstep with the rest of the economy. The study also confirmed that the pandemic period was unique, with a distinct change in volatility patterns that could not be explained by normal market fluctuations alone.

The implications of these findings are significant for anyone managing a portfolio. The idea that small businesses are automatically a riskier bet appears to be an exaggeration, as their long-term risk levels are similar to those of large, sustainable companies. Furthermore, the ESG index appears to be a stable choice during times of crisis because it does not overreact to bad news, making it a potentially strong alternative when markets are turbulent. On the other hand, the small business index, while offering higher returns in the post-pandemic era, is more sensitive to negative shocks and moves independently of the broader market. This independence makes it a useful tool for diversification, allowing investors to spread their risk across different types of assets that do not all react the same way to the same events. Ultimately, the study suggests that the landscape of investing is more nuanced than simple labels of "safe" or "risky," with both small enterprises and sustainable giants offering unique and valuable characteristics depending on the market conditions.