Time to reform the Ghana Reference Rate: From Treasury Bill Yields to Banks’ Deposit Costs

The Ghana Reference Rate (GRR) is a crucial benchmark for businesses seeking credit to purchase equipment, restock shops or meet payroll expenses. However, its usefulness is dependent on how accurately it reflects financing conditions and whether borrowers can comprehend its impact on the interest rates they pay. The central weakness of the GRR lies in its composition, which blends policy signals, interbank borrowing, and government investment returns without directly measuring banks' deposit costs.

Additionally, the reserve adjustment grants Treasury bill movements greater influence than the initially intended 40% weight suggests.

The article raises two main questions: whose cost is the GRR measuring, and why should bank deposit costs replace government borrowing rates in the GRR formula? To address these questions, it is essential to examine the formula for the GRR, which includes the annualised 91-day Treasury bill rate (T₉₁), the cash reserve ratio (CRR), and the cash-in-vault ratio (CIV). The denominator, representing the share remaining after deducting CRR and CIV, currently sums to 100%, with the three stated weights also adding up to 100%.

A 5.38% Treasury bill rate, for instance, enters the formula as 6.90% before the 40% weight is applied. This demonstrates that the Treasury bill component carries more weight in the GRR calculation than initially apparent. Specifically, a one percentage-point rise in the Treasury bill rate increases the formula-based GRR by 0.513 percentage points, while the same rise in the policy rate adds 0.400 percentage points, and an interbank increase adds 0.200 points. These comparisons remain constant when other inputs are held constant.