Negative arbitrage occurs when invested proceeds earn less than the borrowing or refunding cost, reducing financing efficiency.
Negative arbitrage occurs when the return on invested funds is lower than the cost of borrowing those funds. In public finance, it often describes the lost savings that occurs when bond proceeds or refunding escrow funds earn less than the yield or interest cost on the bonds.
The term is especially important in municipal bond issuance and refunding. An issuer may borrow before project funds are needed or before old bonds can be redeemed. If the proceeds are invested at a lower rate during that waiting period, the spread reduces net savings.
| Situation | Borrowing side | Investment side | Negative arbitrage issue |
|---|---|---|---|
| Construction proceeds | Issuer pays bond interest before spending proceeds. | Proceeds are invested short term. | Investment earnings may not cover bond interest cost. |
| Advance refunding escrow | Refunding bond yield or borrowing cost. | Escrow securities until call date. | Escrow yield may be below refunding bond cost. |
| Treasury or cash reserve | Institution funds a position or reserve. | Funds sit in lower-yielding instruments. | Carry cost reduces net return. |
A city issues $20 million of bonds for a project that will spend down over two years. The bonds carry an effective cost of 4.25%, but unspent proceeds can be invested only at about 3.25% after legal and policy constraints. The 1.00 percentage-point gap is negative arbitrage while the funds remain invested.
The actual cost depends on the spending schedule, reinvestment rates, tax rules, eligible investments, and whether the issuer could have delayed issuance or staged the borrowing.
| Evidence | Why it matters |
|---|---|
| Bond yield or borrowing cost | Establishes the cost side of the spread. |
| Investment yield on proceeds or escrow | Establishes the earnings side of the spread. |
| Spending or redemption schedule | Determines how long the negative spread lasts. |
| Present-value savings analysis | Shows whether refunding savings survive negative arbitrage. |
| Tax certificate and arbitrage rebate workpapers | Supports compliance with tax-exempt bond rules. |
| Investment policy and permitted investments | Explains why higher-yielding investments may not be available or appropriate. |