ETFs tracking homebuilders were the weakest performers Wednesday after the National Association of Realtors said existing homes sold at a 6.33 million annual clip last month. That was down 4.1% from 6.62 million a month earlier. Following the report, the Philadelphia Housing Sector Index was falling by 1.3%.

The iShares Dow Jones U.S. Home Construction ( ITB) ETF was losing 85 cents, or 2.4%, to $34.31. The SPDR Homebuilders ( XHB) ETF was giving back 67 cents, or 2.2%, to $30.50, and the PowerShares Dynamic Building & Construction ( PKB) ETF was recently down 26 cents, or 1.8%, to $14.46.

ETFs related to crude and energy were also among the day's biggest decliners. Crude oil for October delivery dropped after the Energy Department said U.S. crude inventories fell by a smaller-than-expected 600,000 barrels. Meanwhile, gasoline inventories unexpectedly rose by 400,000 barrels.

The Energy Select Sector SPDR ( XLE) ETF sank 1.6% to $57.34, the PowerShares Dynamic Energy Exploration ( PXE) ETF was recently lower by 1.4% to $19.27, and the iShares Dow Jones U.S. Oil Equipment Index ( IEZ) ETF slid 1.4% to $44.90.

After National Semiconductor ( NSM) cut its quarterly sales forecast late Tuesday, semiconductor-tracking ETFs fell. The PowerShares Dynamic Semiconductors ( PSI) ETF was off 10 cents, or 0.6% to $16.14, and the SPDR Semiconductor ( XSD) ETF were recently lower by 25 cents, or 0.5% to $45.44.

Meanwhile, the iShares Silver Trust ( SLV) ETF was Wednesday's biggest winner, recently gaining $2.17, or 1.8%, to $125.12, as the price of silver climbed.

The PowerShares Lux Nanotech ( PXN) ETF was another of the gainers, thanks to a 9.6% rise in major holding NVE Corp. ( NVEC). The ETF was higher by 9 cents, or 0.5%, to $17.04.