The yuan spiked in opening trading Monday, in a hint that authorities may have taken another tool back out of the box to help stabilize the under-pressure currency.

The onshore yuan jumped as much as 0.5% to trade exactly at 7.2157 — the day’s reference rate for the managed currency — before falling back, according to official pricing data. Banks including state-owned ones sold dollars in thin liquidity resulting in the rapid rise and that selling ended after it reached the fixing level, according to two traders who asked not to be named as they are not authorized to speak publicly.

The move echoed opening trading at times last fall, when the currency showed a pattern of similar early gains, after regulators urged banks to respect “the authority of the fixing.” Setting the daily reference rate limits the onshore yuan’s moves by 2% either side of it.

Authorities have been signaling their discomfort with yuan weakness by setting the fixing at noticeably stronger-than-expected levels since last week. Late Friday, the People’s Bank of China said at a quarterly meeting of the monetary policy committee it will adopt “comprehensive measures and stabilize expectations” about the currency and will “resolutely prevent risks of big fluctuations.”

“The PBOC may have to unleash similar measures like last year if the yuan continues to weaken in the third quarter,” said Stephen Chiu, chief Asia FX and rates strategist at Bloomberg Intelligence.

The yuan had fallen more than 5% last quarter against the dollar, dragged down by China growth concerns as well as its widening monetary policy divergence with the US.