Bundled securities tracking utilities were among the best performers of Wednesday's wild session.

Among individual names, Exelon ( EXC), American Electric Power ( AEP), Edison International ( EIX) and FirstEnergy ( FE) were all rising by 2.6% or more.

The Ultra Utilities ProShares ( UPW) was adding $1.74, or 2.4%, to $74.73. The PowerShares FTSE RAFI Utilities ( PRFU) gained $1.24, or 2.3%, to $56.30. The Utility HOLDRs ( UTH) was higher by $2.22, or 1.6%, to $138.73. The PowerShares Dynamic Utilities ( PUI) was up 29 cents, or 1.6%, to $18.57.

The United States Natural Gas ( UNG) ETF was also climbing, as natural gas was gaining 21 cents to $6.40 per million British thermal units. The ETF added $1.33, or 3.4%, to $40.69.

A ramp up in shares of Merck ( MRK) boosted several pharmaceutical ETFs. On Tuesday, a New Jersey court ruled that English and Welsh patients cannot sue the company over health problems emanating from the use of the painkiller Vioxx. Shares of Merck were up 2.3%.

The SPDR S&P Pharmaceuticals ( XPH) rose 31 cents, or 0.9%, to $33.30. The Pharmaceutical HOLDRs ( PPH) was gaining 81 cents, or 1.1%, to $77.70. The iShares Dow Jones U.S. Pharmaceuticals ( IHE) was up 5 cents, or 0.1%, to $52.54.

On the other hand, ETFs tracking REITs and the housing sector were lower on fears of spreading credit problems. First, Bear Stearns ( BSC) said that it is facing losses in a third mortgage-related fund. Additionally, rumors abounded that Beazer Homes ( BZH) had a liquidity problem that could lead to a bankruptcy filing. The company later denied the rumor, but not before it took down the rest of the homebuilder stocks.

The iShares FTSE NAREIT Retail ( RTL) was losing $2.50, or 6.2%, to $38.18. The iShares FTSE NAREIT Mortgage REITs ( REM) was lower by $2.35, or 6.7%, to $32.50. The Ultra Real Estate ProShares ( URE) slumped $1.19, or 2.9%, to $40.06.

Elsewhere, the iShares Dow Jones U.S. Home Construction ( ITB) was losing 96 cents, or 3.6%, to $25.60. The SPDR S&P Homebuilders ( XHB) was down 59 cents, or 2.2%, to $25.87.

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