The premium is the payment for holding both legs
Positive basis exists because leveraged longs will pay to be long. Harvesting it means being the patient counterparty on both sides. Watch how the same premium shows up as a funding stream on the funding-rate arbitrage calculator, and measure the raw gap on the futures basis calculator.
Harvesting the futures premium, neutrally
Cash-and-carry: buy spot, short the dated future against it, hold to expiry. The futures premium (basis) converges to zero on settlement day, and the short captures it — direction-neutral, with the annualized yield fixed at entry. A 2.5% premium with 60 days left locks ~16% annualized, paid in the currency of convergence.
The deductions that shrink the banner number: entry and exit fees on both legs (~0.15–0.3% total), spot custody or transfer costs, and margin efficiency — the short leg needs collateral, so your capital earns the yield on less than its full weight. Realistic net on that 16% gross is nearer 12–13%, still handsome when spot rates elsewhere are low, pedestrian when they aren't.
The risks people wave away: early-exit basis risk (the premium can widen before it converges — mark-to-market pain on the short), exchange risk on both venues for the duration, and the funding-rate alternative constantly repricing the opportunity. The trade is genuinely low-risk held to term on one solvent venue; every deviation from that sentence reintroduces the market.