Funding Rate
The implicit cost of carrying a futures position, reflecting the interest cost of financing the notional exposure of the contract, equivalent to the forward premium above spot prices that compensates the seller of futures for deferring settlement.
In financial theory, the price of a futures contract should reflect the spot price of the underlying adjusted for the cost of carry — primarily the risk-free interest rate over the contract's life. A futures buyer who does not pay the full notional price upfront (paying only margin instead) effectively has the remaining capital available for other uses. The seller, conversely, foregoes the cash proceeds that would have come from selling in the spot market. The futures price compensates for this deferral through what was conceptually a funding rate embedded in the forward premium.
In India's exchange-traded futures, there was no explicit funding rate payment between buyer and seller — the rate was implicitly embedded in the futures price. A Nifty futures contract expiring in one month was priced above the spot Nifty level by approximately the risk-free rate multiplied by the time fraction remaining. If the one-month repo rate was 6 percent per annum and thirty days remained to expiry, the fair futures premium over spot was approximately 0.5 percent. This was the annualised funding rate for one month.
In practice, futures prices deviated from theoretical fair value based on cost of carry due to supply and demand — if there was excess buying of futures (bullish sentiment), futures could trade at a premium above theoretical cost-of-carry price (super-contango). If futures were sold aggressively, they could trade below fair value (discount to spot), which implied a negative implied funding rate.
For cash-futures arbitrageurs in India, the funding rate was the central variable. An arbitrageur who bought the spot basket (replicating Nifty) and shorted Nifty futures earned the futures premium as a risk-free return if held to expiry. The annualised return from this strategy was the implied funding rate — typically comparable to or slightly above short-term money market rates. When futures premiums exceeded money market rates significantly, arbitrage activity increased, compressing the spread back toward fair value.