Housing-related exchange-traded funds were among the worst decliners of Wednesday's session, after more bad news about the housing market.

The National Association of Realtors said its pending home sales index dropped 12.2% in July to a reading of 89.9, providing the latest evidence that the slowdown in housing is continuing. Over the last year, the index has fallen 16.1%.

Following the release, the Philadelphia Housing Sector Index slid 1.7%. D.R. Horton ( DHI), Hovnanian ( HOV), Lennar ( LEN) and Pulte Homes ( PHM) were all down 3.1% or more.

The iShares Dow Jones U.S. Home Construction ( ITB) was losing 87 cents, or 3.6%, to $23.28. The SPDR S&P Homebuilders ( XHB) was down 93 cents, or 3.7%, to $24.38.

Bundled securities tracking real estate were also losing ground following the report on pending home sales. Vornado Realty Trust ( VNO), Simon Property Group ( SPG) and Kimco Realty ( KIM) were all lower by 2% or more.

The Ultra Real Estate ProShares ( URE) was falling $2.19, or 4.8%, to $43.50. The SPDR Dow Jones Wilshire International Real Estate ( RWX) was down $1.54, or 2.5%, to $61.04. The WisdomTree International Real Estate ( DRW) ETF was off by $1, or 2%, to $48.70.

Retail ETFs also were tumbling on the backs of several holdings. Costco ( COST), which missed analysts expectations for August same-store sales, dropped 5%. Target ( TGT), Lowe's ( LOW), Macy's ( M) and Kroger ( KR) were all down 2% or more.

The PowerShares Dynamic Retail ( PMR) was shedding 42 cents, or 2.3%, to $17.84. The Retail HOLDRS ( RTH) was lower by $2.11, or 2.1%, to $98.84. The SPDR S&P Retail ( XRT) was down 89 cents, or 2.3%, to $38.73.

On the other hand, Treasury-related ETFs were among few winners of the day. Recently, the 10-year note was up 16/32 in price, cutting the yield to 4.48%. The 30-year bond was adding 26/32 in price, yielding 4.78%.

The Vanguard Long-Term Bond ( BLV) was up 59 cents, or 0.8%, to $74.93. The iShares Lehman 20+ Year Treasury Bond ( TLT) was gaining 62 cents, or 0.7%, to $89.18. The iShares Lehman 10-20 Year Treasury Bond ( TLH) was adding 63 cents, or 0.6%, to $101.46.