What is a Basis Trade? Definition, Formula, and Example

A basis trade is a leveraged arbitrage strategy that captures the price gap between a cash Treasury bond and its corresponding futures contract, typically financed with short-term repo borrowing.

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What Is a Basis Trade?

A basis trade is a relative-value arbitrage that exploits the "basis" — the small price gap between a cash bond and its corresponding futures contract. In its most systemically important form, a hedge fund buys a cash Treasury note, simultaneously sells the equivalent Treasury futures contract, and finances the cash position in the overnight repo market, layering on 20x to 50x leverage to turn a fractional-cent gap into a meaningful return on capital. The basis converges to zero at futures expiration by construction, which is why the trade is marketed as low-risk — the risk isn't in the spread, it's in the leverage and financing that hold the position open until convergence.

How the Basis Is Calculated

Gross Basis = Cash Bond Price − (Futures Price × Conversion Factor)
Net Basis = Gross Basis − Carry
Carry = Coupon Income Earned − Repo Financing Cost (over the holding period)

The conversion factor normalizes a specific deliverable bond's price to the futures contract's notional 6% coupon standard. When net basis is positive, the cash-futures spread offers more return than the cost of holding and financing the position — the setup a basis trader is hunting for.

Worked Example

A 10-year Treasury note trades at $99.50 per $100 face. The cheapest-to-deliver futures contract trades at $118.00 with a conversion factor of 0.8420:

Futures-adjusted price = $118.00 × 0.8420 = $99.356
Gross basis = $99.50 − $99.356 = $0.144 per $100 face

On a $500 million face-value position — a typical institutional basis-trade clip — that gross basis is worth $720,000. Financed via overnight repo at roughly 20:1 leverage (about $25 million of actual margin capital against the $500 million notional), a modest basis of 14.4 basis points converts into a return in the high single digits on the capital actually deployed, before financing costs and any hedging expense.

When Traders Use It

Relative-value macro hedge funds run Treasury basis trades at massive scale to earn what amounts to a leveraged repo-financed carry spread, and in doing so provide a meaningful share of daily liquidity connecting the cash and futures Treasury markets. Similar basis logic shows up in index futures versus the underlying basket, and in ETF share price versus net asset value. The trade is a pure institutional strategy — it requires prime-broker repo access, not something available through a retail account.

Limitations and Common Misconceptions

The basis trade is not risk-free arbitrage despite the marketing. The risk is funding risk, not price risk: if repo rates spike, haircuts widen, or a prime broker raises margin requirements before the futures contract expires, a fund can be forced to unwind the position at a loss well before convergence — exactly what happened in March 2020, when a repo funding freeze forced rapid basis-trade unwinds that amplified the Treasury market sell-off and prompted direct Federal Reserve intervention. The Fed and the Office of Financial Research have repeatedly flagged record leveraged-fund short positioning in Treasury futures — the basis trade's other leg — as a standing financial-stability risk. A trade that looks "riskless" on a spreadsheet because it converges at expiration can still produce large realized losses if the position is forced to close early.