Overnight borrowing by Hong Kong banks jumped to the highest in almost five months, a sign that a series of interventions to bolster the local currency may be having a desired effect on the money market.

The Hong Kong Monetary Authority (HKMA) loaned out HK$4.67 billion ($595 million) through its so-called discount window on Tuesday, the most since February, according to data compiled by Bloomberg. While the overnight interbank offered rate has remained close to zero, the one-month equivalent has doubled from a mid-June low.

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The spike in overnight borrowing may reflect banks turning to central bank liquidity as the interventions drain cash from the system, a move aimed at easing pressure on the currency. Low funding costs have allowed traders to borrow the Hong Kong dollar cheaply and use it to buy the higher-yielding greenback.

However, the move may also be down to technical factors such as a one-off need for liquidity from an institution.

The HKMA bought the local dollar for a third time in a week in July to prevent the currency from falling below the weak end of its permitted trading band.

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Stephen Chiu, chief Asia FX and rates strategist at Bloomberg Intelligence, is watching the city’s aggregate balance — a component of its monetary base — for signs that borrowing costs may rise. That currently stands at just under HK$120 billion and is depleted every time the HKMA intervenes and buys Hong Kong dollars.

“I think once the aggregate balance shrinks below the HK$70 billion to HK$80 billion mark toward earlier lows near HK$50 billion, then it’s hard for rates not to respond,” he said.