How Arbitrage Funds Actually Generate Returns — The Cash-Futures Spread Explained
Arbitrage funds occupy an unusual position in the mutual fund universe: they are classified as equity-oriented funds for taxation purposes (making them attractive from a tax standpoint relative to debt funds), yet their actual investment strategy has almost nothing to do with directional equity market views. Understanding how they actually make money clears up a lot of the confusion around this category.
The Core Strategy: Buying Cash, Selling Futures
An arbitrage fund's central strategy is to simultaneously:
- Buy a stock in the cash (spot) market, and
- Sell an equal quantity of that same stock's futures contract on the derivatives market. This creates a fully hedged position — the fund is long the stock in cash and short an equivalent position in futures at the same time. Because the position is hedged, the fund is not exposed to whether the stock's price goes up or down; both the cash holding and the futures position move in opposite directions and largely offset each other.
Where the Actual Profit Comes From
The profit doesn't come from the stock's price movement — it comes from the spread between the futures price and the spot price, known as the cash-futures spread or the "cost of carry." A stock's futures price is normally higher than its spot price, reflecting the cost of carrying that position forward to the futures contract's expiry (interest cost, adjusted for expected dividends). This spread exists because market participants are willing to pay a small premium to take a leveraged, forward-dated equity position rather than paying for the stock outright today.
Here's the mechanism in a simplified illustration:
- Suppose a stock trades at ₹1,000 in the cash market, and its one-month futures contract trades at ₹1,008 — a ₹8 premium.
- The arbitrage fund buys the stock at ₹1,000 and simultaneously sells the futures contract at ₹1,008.
- At expiry, regardless of where the stock's actual price ends up — say it rises to ₹1,050, or falls to ₹950 — the fund settles its futures position and unwinds the cash position, and the net outcome is the same: it locks in the ₹8 spread it captured at initiation, because the loss (or gain) on one leg is offset almost exactly by the opposite gain (or loss) on the other. The fund essentially earns this spread as a return, annualised, which historically has tended to track short-term money market rates fairly closely, since the spread itself is largely a function of prevailing interest rates and dividend expectations.
Why the Spread Exists and When It Widens or Narrows
The cash-futures spread isn't random — it's driven primarily by prevailing short-term interest rates (a higher rate environment typically supports a wider spread) and by expected dividends on the underlying stock (an anticipated dividend payment before expiry tends to compress the spread, since holders of the futures contract don't receive that dividend the way a cash-market holder does). The spread also tends to widen during periods of higher market volatility or strong bullish sentiment, when there's more demand to take leveraged long positions via futures rather than buying stock outright — which is why arbitrage fund returns, while generally stable, do fluctuate somewhat with market conditions rather than being perfectly fixed.
Why Arbitrage Isn't "Free Money"
While the strategy is genuinely market-neutral in the sense that it doesn't depend on stock prices going up, it isn't risk-free in an absolute sense:
- Spread compression risk — in periods of low volatility or bearish sentiment, cash-futures spreads can shrink, sometimes close to zero, meaning arbitrage funds can deliver very low returns during such stretches.
- Execution and liquidity risk — the strategy depends on being able to simultaneously execute both legs (cash purchase and futures sale) efficiently; in illiquid stocks or during volatile sessions, execution slippage can eat into the theoretical spread.
- Rollover risk — as futures contracts approach expiry, funds must "roll" positions into the next month's contract, and the spread available at rollover isn't guaranteed to match the previous contract's spread.
- Idle cash allocation — arbitrage funds don't always find enough attractive spread opportunities across the market to deploy their entire corpus, and unutilised cash may sit in lower-yielding instruments, slightly diluting overall returns.
Why Arbitrage Funds Are Popular Despite Modest Returns
Arbitrage funds have carved out a specific niche primarily because of their tax treatment: since they are classified as equity-oriented funds (holding at least the SEBI-prescribed minimum equity-related exposure, achieved through the combination of cash-market stock plus hedged futures exposure), gains are taxed under equity capital gains rules rather than debt fund taxation — which, for investors in higher tax brackets with a holding period exceeding one year, can be meaningfully more tax-efficient than a comparable-return debt or liquid fund, despite arbitrage funds delivering returns broadly comparable to short-term debt instruments before tax.
Why This Matters
Arbitrage funds are often mis-sold or misunderstood as "equity funds with equity-like return potential" — they are not. Their return profile is fundamentally closer to a low-risk, money-market-like instrument, generated through a fully hedged spread capture strategy rather than any directional market view, and their real appeal lies in the tax-efficient wrapper this equity-oriented classification provides for money that would otherwise sit in a comparable-duration debt instrument.