This is because, if investors had forgotten the fact that recovery into 2010 is not going to be a sprint, then this week may have been a healthy reminder, preventing exuberance that may have led to an even larger market letdown later in the year. As I have said in my outlook for 2010, the year will test the market's stamina. I think this week was the first but probably not the last example of why this will be true.

With that in mind, here are this week's ETF winners and losers:

Winners

ProShares UltraShort China ( FXP) +11.4%

There were plenty of inverse and inverse leveraged ETFs dominating the winners this week, but it was China's tightening of monetary policy (and fears of further tightening) that triggered much of the week's global selloff, earning FXP a well deserved spot as a winner this week.

PowerShares DB U.S. Dollar Bullish Fund ( UUP) +1.4%

The U.S. dollar index snapped higher after the euro sold off. A stronger yen tempered the gains, however, and while the U.S. dollar has appreciated vs. the euro, UUP did not break its December highs.

iShares Barclays 20+ Year Treasury ( TLT) +1.1%

SPDR Barclays Long Term Treasury ( TLO) +1.0%

Investors sought shelter from the storm last week and they gravitated to U.S. Treasuries. A stronger U.S. dollar didn't hurt either, as it made dollar-denominated assets more attractive to own.

Losers

Market Vectors Coal ( KOL) -10.6%

The most favored ETFs of the previous few weeks and months became the most sold this week. There wasn't any other reason for the selloff in KOL, for instance, although it was hurt a bit by exposure to China. Investors are worried that monetary tightening will crimp economic growth, and that could lead to lower than expected coal demand.

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