A Tiny STT Change Can Quietly Affect Your Mutual Fund Returns. Here’s how

Published on: February 13, 2026

Securities Transaction Tax (STT) is a small tax charged by the government every time you buy or sell shares or derivatives on the stock exchange. It is applied on the value of the transaction, not on the profit you make.

The Securities Transaction Tax (STT) on futures trades was recently increased from 0.02% to 0.05%. At first glance, it doesn’t look like much. It’s just three basis points.

No dramatic headlines. No market panic. No visible price shock.

So, most investors might naturally wonder: Does this even matter?

The answer is: yes, more than it appears.

Because this isn’t the kind of change that shakes markets immediately. It’s the kind that quietly reshapes return expectations over time.

The Real Impact Lies Beneath the Surface

The key thing to understand is this:

STT on futures is charged on the notional value of the contract, not on profits. That means it applies every time a futures position is entered or rolled, regardless of whether a trade makes or loses money.

This matters because futures aren’t just speculative tools. They form the backbone of arbitrage strategies, especially within certain mutual fund categories.

And when strategies operate on thin margins, even small cost changes can have a meaningful effect.

Why Arbitrage Funds Feel the Impact the Most

Among all mutual fund categories, arbitrage funds are the most directly affected. Their core strategy is simple in concept:

They buy stocks in the cash market and simultaneously sell futures contracts to lock in a small price difference between the two. These spreads are usually modest, often around 4-6% annualised before costs.

That means profitability depends heavily on efficiency and cost control. With the increase in STT on futures:

Transaction costs rise immediately
Arbitrage spreads effectively compress
Net post-expense returns decline

And because arbitrage funds roll futures positions every month, this isn’t a one-time cost. It becomes a recurring structural expense.

Over time, this can lead to:

Lower yields compared to previous years
Returns drifting closer to liquid fund levels
Reduced attractiveness when market volatility is low

Importantly, tax treatment for investors does not change. If held for more than one year, arbitrage funds continue to enjoy equity-style taxation.

But the engine that generates returns becomes slightly weaker.

What About Other Mutual Fund Categories?

The impact is not uniform across the industry.

Index Funds and ETFs: Minimal effect.

These funds typically do not rely on futures roll-down strategies to generate returns.

Active Equity Funds: Indirect and limited impact.

Some funds use futures for hedging or tactical positioning, but this is not their primary return driver.

Costs may rise marginally, but not meaningfully.

Debt Funds: No impact at all.

Futures STT is irrelevant to their investment process.

How Fund Managers Are Likely to Respond?

When costs rise structurally, strategies tend to adapt. Fund managers are likely to:

Be more selective in choosing arbitrage opportunities
Reduce unnecessary churn in futures positions
Roll positions only when spreads justify costs
Accept lower steady-state return expectations

As a result, arbitrage funds may become more sensitive to market conditions than before.

What This Means for Investors?

Arbitrage funds were never designed to be high-return products. They were designed to be consistent, tax-efficient parking tools.

With the increase in STT on futures, investors should adjust expectations accordingly.

It is reasonable to expect:

Slightly lower and more variable returns
A narrower gap between arbitrage and liquid fund yields
Greater dependence on market spreads for performance

This change does not make arbitrage funds irrelevant. It simply means they should be used for what they were always meant for:

Stability, liquidity, and tax efficiency, not return chasing.

The Larger Lesson

Not every market change arrives with loud signals. Some arrive quietly, buried inside cost structures rather than price charts. And over time, those are often the changes that matter the most.

The increase in futures STT does not disrupt markets. But it does subtly shift how certain strategies perform.

For investors, the takeaway is simple: Understanding where returns come from is just as important as tracking where markets are headed.

To stay connected and updated with more such educational, data-driven content:

Consistent learning is the most underrated edge in long-term investing.

Prasiddh Shroff