If this month has felt like a wild ride for stock investors, it has been positively hair-raising for those in the commodities market

Price swings for raw materials reached the highest levels in more than a year as investors initially celebrated the prospect of U.S. monetary easing and then panicked at the possibility China would be too severe in its attempts to cool its economy.

Prices of everything from gold to copper and cotton leapt to new highs, only to be slapped down just as quickly. Trading volume in many commodities roared to records, including for silver, cotton and corn.

Since the beginning of October, the Dow Jones-UBS Commodity Index's 30-day realized volatility has doubled to 25%, the highest since September 2009.

The moves were particularly striking because stock-market volatility has been relatively benign, even with triple-digit moves in the past few sessions. The same measure of 30-day volatility in the Standard & Poor's 500-stock index is near six-month lows.

For commodities, the overarching reason for the volatility is the outsize reaction to new signs that China has stepped up its moves to tighten credit and contain inflation. But the huge amount of money flooding into commodities markets appears to be helping exaggerate those moves.

With that money has come a new breed of investors more focused on trading in and out of commodities to profit from price moves rather than the standard producers and consumers relying on the market to manage their risks.

Since August, money managers, such as hedge funds, have raised their bullish bets on oil, copper, soybeans and many other markets. These funds' total net-long positions all peaked in the week ended Nov. 9, before being cut in the past week, according to the Commodity Futures Trading Commission.

All this suggests volatility will at least be around, if not increase, in the short term, even if many people believe commodities overall have a lot further to rally.

'When you have this large [speculative] exposure built up, you do run a risk,' said Tim Evans, a commodity analyst at Citi Futures Perspective, a commodity-research arm of Citigroup. Because 'you've used up your potential to draw in more new money -- that's the time when you are vulnerable to a reversal.'

That may have started.

Since Nov. 9, the Dow Jones-UBS Commodity Index has declined 7%, amid waves of selling triggered by China's moves to tackle inflation.

Of all the commodities that were whipped around, those directly affected by demand from China suffered most. Zinc sank 16%, cotton shed 15%, and crude oil fell 7%.

Investors 'are getting more and more nervous as we get close to year end,' said Andy Smith, senior commodity strategist at Bache Commodities. They are 'not sure whether they should take the money off the table and run for the year or stay in the game.'

Commodity consumers around the world are making real-time assessments about whether they should jump in and buy now or wait for better prices.

Many are balancing not just fundamental supply-and-demand data but also macro forces such as monetary policy in China and the U.S.

The debate over how fast China's economy may expand and whether other emerging markets will step down hard on their economies also is driving some of the price swings.

The current volatility is a 'fundamental manifestation of uncertainty about the pace of rising demand,' said Colin P. Fenton, head of global commodities research and strategy at J.P. Morgan Chase.

Consumer prices in China rose 4.4% in October from a year earlier, a 25-month high, setting off a slew of anti-inflation moves, including an increase in bank reserve requirements and talk of possible price controls.

China has been the main source of demand growth for many commodities.

This year, the country's oil consumption is expected to increase 820,000 barrels a day, or 35% of the world's total oil consumption growth, according to the International Energy Agency.

The country has an even bigger influence in other markets, accounting for 70%, 57% and 46% of this year's global consumption rise for cotton, copper and soybeans, respectively.

'If you think China will grow less as a result of these policies, the next logical conclusion will be commodity demand from that country will also moderate given its importance' in terms of generating demand growth, said Harry Tchilinguirian, head of commodity markets strategy at BNP Paribas.

Some expect China's measures will only temporarily damp price increases for raw materials and won't hurt the nation's real appetite for commodities. Even if China's economy expands at a slightly slower rate, it will be a huge force in the commodities market.

'The steps that they're taking so far will have only a marginal impact,' said Dwight Anderson, managing partner at Ospraie Management LLC, a hedge fund specializing in commodities.

Soon, the markets will come to 'conclude that the global economic recovery is intact and there will be sustained growth, especially in the emerging markets, for commodity imports,' Mr. Fenton said.

Other analysts even see a silver lining to China's cooling moves.

China is taking pre-emptive measures to tackle inflation. In 1994, when inflation ran up to 27.7%, the country's central bank didn't increase interest rates but waited until a year later when the economy lost steam.