Here's a look at the best and worst of exchange-traded funds this week.

Winners

PowerShares DB Crude Oil Double Short ( DTO) +17.8%

I first mentioned DTO as a hedge against falling markets on Monday, when it was trading around $87. I offered it as a way to bet on falling energy prices on Wednesday (instead of shorting U.S. Natural Gas ( UNG)) when it was trading around $91.50. It turned out to be one of the best performing ETFs and ETNs this week.

Besides DTO, I also mentioned PowerShares DB U.S. Dollar Bullish ( UUP) and CurrencyShares Japanese Yen ( FXY). UUP was flat for the week and FXY gained more than 3% from last week's close.

Market Vectors Indonesia ( IDX), up 2.2% was also a winner. I mentioned it on Thursday following the re-election of President Yudhoyono and covered it in more detail previously.Investors hope that his victory will lead to a Chinese-style infrastructure build-out that can deliver accelerated GDP growth.

iShares South Korea ( EWY), +2.5%, bounced higher this week after Samsung, it's No. 1 holding at more than 16% of assets, guided analysts higher for second-quarter earnings on Monday. EWY gained for the week, but it lost the Samsung gains and closed below its Monday open. A suspected North Korean led cyberattack on South Korea and U.S. systems may have contributed to the tepid week.

Losers

PowerShares WilderHill Clean Energy ( PBW) -12.1%.

Market Vectors Solar ( KWT) -12.7%.

With the S&P 500 index down 1.9% for the week, there were a lot more losers than winners. Solar ETFs were one sector that took a beating. Solar ETFs tend to track oil, but with more volatility.

iShares FTSE NAREIT Retail ( RTL) -9.7%.

The retail sector had mixed same-store sales reports. They were mostly down, but better than expected in many cases, and PowerShares Dynamic Retail ( PMR) had a 0.5% gain for the week. Meanwhile, the extremely thinly traded iShares FTSE NAREIT Retail ( RTL), which invests in retail real estate, tanked 9.7%. This fund suffers from being in two of the weaker sectors of the economy -- retail and commercial real estate.

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