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After the recent big rally for commodities, analysts are buzzing about a possible break in the buying — and blaming China.

Exchange authorities in China have increased transaction costs for commodities traders amid fears about a speculative bubble, according to multiple media reports.

“This, together with China’s upcoming Labor Day holiday, should see a short-term pullback in trade activity and commodities prices,” said Morgan Stanley analysts in a note dated Monday, according to a Bloomberg report.

The upcoming holiday is also called May Day or International Workers’ Day, and it’s aimed at honoring the blue-collar crowd and even desk jockeys, similar to the U.S. Labor Day holiday in September. The May 1 holiday falls on Sunday and is celebrated around the world, sometimes with Soviet-era touches.

Exchanges in Shanghai and Hong Kong are slated to be closed this coming Monday in observance of the holiday. U.K. traders also will have the day off thanks to an early May bank holiday. That’s all likely to weigh on global trading activity.

Meanwhile, the crackdown by exchanges in Dalian, Shanghai and Zhengzho means higher trading margins and fees, a Reuters report said. The moves by authorities come after speculative trading soared following a credit surge engineered by Chinese policy makers, a Financial Times report said.

In China, “full-on speculative fever seems to have taken hold,” a Wall Street Journal column said. Turnover in Shanghai was higher last week for a previously obscure futures contract for steel reinforcing bars, or rebar, than it was for that city’s entire stock market, the column said.

Perhaps “rebar” could even start trending on Twitter thanks to posts like this:

Amazing measure of trading in Chinese commod futures. Avge tenure of rebar & iron ore posns < 4hrs vs 70 for Nat Gas

— Robert Rennie (@R0bertRennie) April 26, 2016

In commodities trading on Tuesday, June gold futures

GCM6, +0.27%

 have been lower, but June West Texas Intermediate crude

CLM6, +3.17%

has been trading higher, helped by a weakening dollar

DXY, -0.23%

Read more: 4 things Saudi Arabia’s reform plan says about the oil market

“Positioning could easily become far more positive yet on U.S. futures exchanges before it begins to look stretched, although perhaps not in China,” the Journal column said.