Chinese shares plunged Monday, close to their low reached during last summer’s crash, while authorities appeared to sit on the sidelines, overshadowing their recent moves to calm markets by steadying the yuan.

The Shanghai Composite Index SHCOMP, +2.06% fell 5.3% to 3,016.70, the lowest finish for the benchmark in three and a half months. It has shed 15% so far this year. Another 3% drop, or 89 points, would put the benchmark below its close of 2,927.29, reached on Aug. 26.

The smaller Shenzhen Composite Index 399106, +1.50% fell 6.6% to 1,848.10.

Meanwhile, the central bank nudged China’s yuan stronger, after the currency’s swift weakening last week triggered global selling.

Shares in Hong Kong sank to their lowest in roughly two and a half years. The Hang Seng Index HSI, +0.47% was off 2.8% at 19,888.50, closing below 20,000 for the first time since June 2013. A gauge of Chinese firms listed in the city fell 3.9%.

Australia’s benchmark S&P/ASX 200 XJO, -0.31% was down 1.2%, and South Korea’s Kospi 180721, +0.25% fell 1.2%. Japan’s market was closed for a national holiday.

China market misery deepens

State-owned funds were notably absent from the market Monday, traders said, as shares plunged in the last hour of trading. Buying by China’s so-called “National Team,” particularly in late-session spurts, had helped stabilize the market last summer and, at times, late last year.

“[All] this may have conveyed a sense of sanguinity from regulators and the government regarding recent market volatility,” said Bill Bowler, equities sales trader at Hong Kong-based research and brokerage firm Forsyth Barr Asia.

Authorities’ poorly telegraphed moves in the currency market last week sent the Shanghai Composite Index down 10% and sparked selling in the rest of the region, the U.S. and Europe. While moves to steady the currency buoyed shares on Friday, the ambiguous policy outlook has made stock-market investors pessimistic, says Jacky Zhang, an analyst at BOC International.

Traders and analysts also said that some investors — hopeful the central bank would introduce fresh easing over the weekend given the disastrous start to the year for stocks and the slowing domestic economy — were disappointed Monday. Many still expect officials to take action later this year, including further cuts to interest rates and the amount of reserves banks are required to hold, although authorities haven’t hinted at any such plans recently.

Fresh signs that China’s currency turmoil spread across the water to Hong Kong also unnerved investors. The short-term rate banks in the city charge each other to borrow Chinese yuan jumped to a record 13.4% from 4% on Friday. Traders said large Chinese banks have been buying the offshore yuan, which trades freely, in an apparent effort to close the gap with the onshore price, tightening liquidity across the border.

Earlier Monday, China’s central bank fixed the yuan CNYUSD, 0.05 at 6.5626 against the dollar, guiding the currency stronger from its 6.5636 fixing on Friday. It was the second day the bank guided the yuan stronger, after eight sessions of weaker guidance. The onshore yuan can trade up or down 2% from the fix.

The onshore yuan was last at 6.5833 against the U.S. dollar, compared with 6.5938 late Friday. It reached a five-year low of 6.5956 last Thursday.

The offshore yuan, which trades freely, was last at 6.6727 to the U.S. dollar, compared with 6.6820 late Friday. It reached a five-year low of 6.7511 on Thursday.

China’s central bank appears to have spent huge amounts of dollars to support the yuan amid decelerating economic growth and the onset of higher U.S. interest rates.

The country’s foreign-exchange regulator said over the weekend that its reserves are “relatively sufficient.” Reserves dropped by $107.9 billion in December, the biggest monthly drop ever.

Worries about slackening demand in China, one of the world’s biggest consumers of commodities from oil to copper, trammeled prices early Monday. Copper US:HGH6 fell to a six-and-a-half year low of $4,416 a ton before recovering to $4,485.

Brent crude oil UK:LCOG6 was down 2% at $33.26 a barrel. The global oil benchmark has fallen more than 13% year-to-date amid China worries and Middle East tensions.

The plethora of reasons for global unease — from China’s slowdown to tensions in the Middle East and North Korea’s nuclear test — has sent investors toward haven assets.