The PowerShares Lux Nanotech ( PXN) exchange-traded fund was the top performer of Tuesday's winning session, thanks to gains in several of its holdings.

Among them, Elan ( ELN) and Accelrys ( ACCL) were both higher. The PowerShares Lux Nanotech was recently higher by 90 cents, or 5.5%, to $17.38.

Bundled securities tracking real estate investment trusts were also higher, thanks to a second-quarter earnings beat by Vornado Realty Trust ( VNO), which was up more than 4%. Simon Property Group ( SPG), ProLogis ( PLD) and Kimco Realty ( KIM) were adding 1.4% or more.

The Ultra Real Estate ProShares ( URE) was rising $1.32, or 3.1%, to $43.35. The Vanguard REIT Index ( VNQ) was higher by $1.17, or 1.8%, to $66.52. The iShares Dow Jones U.S. Real Estate ( IYR) climbed 99 cents, or 1.4%, to $72.34. The SPDR Dow Jones Wilshire International Real Estate ( RWX) was adding $1.39, or 2.3%, to $61.74.

ETFs related to European markets were also among the best performers. Recently, London's FTSE was gaining 2.2%, and Frankfurt's DAX climbed 1.6%.

The PowerShares Dynamic Europe ( PEH) climbed 76 cents, or 3.1%, to $25.44. The Europe 2001 HOLDRs ( EKH) was tacking on $2.50, or 3%, to $85.45. The iShares MSCI United Kingdom Index ( EWU) was adding 45 cents, or 1.8%, to $24.87.

On the flip side, the United States Natural Gas ( UNG) ETF was the biggest loser, as natural gas futures fell by 29 cents to $6.21 per million British thermal units. The ETF was falling by $1.80, or 4.3%, to $39.63.

The Broadband HOLDRs ( BDH) was down 1.9%, after holding Alcatel-Lucent ( ALU) reported an unexpected quarterly loss that sent its stock down 10.5%. The ETF was shedding 19 cents to $15.63.

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