Exchange-traded funds tracking homebuilders, financials and REITs were all falling hard Friday, as investors fretted about the health of credit markets. Shares of American Home Mortgage ( AHM) slid nearly 50% after it said it is slashing roughly 90% of its workforce, and published reports now say the company will shut down after failing to find a buyer for its operations. Among REIT-related ETFs, the iShares FTSE NAREIT Mortgage REITs ( REM) was dropping $1.63, or 4.8%, to $32.59. The Ultra Real Estate ProShares ( URE) ETF gave back $1.37, or 3.2%, to $41.50. The Vanguard REIT Index ( VNQ) ETF was tumbling $1.46, or 2.2%, to $65.58. In the financial sector, Bear Stearns ( BSC) was getting crushed after Standard & Poor's cut its rating outlook for the broker to negative, from stable. Earlier this week, the company said it is facing losses in a third mortgage-related fund. The stock was recently down 2.2%. Other lenders and finance names were losing ground. Countrywide ( CFC), Lehman Brothers ( LEH) and Merrill Lynch ( MER) slid 2% or more. The Rydex S&P Equal Weight Financials ( RYF) was dropping $1.40, or 3%, to $45.76. The First Trust Financials AlphaDex ( FXO) ETF was down 39 cents, or 2.2%, to $17.71. The PowerShares Dynamic Financials ( PFI) was giving back 42 cents, or 1.7%, to $24.32. Homebuilders were feeling the crunch as well. Beazer Homes ( BZH), D.R. Horton ( DHI), Hovnanian ( HOV) and Meritage Homes ( MTH) were losing 4% or more. The iShares Dow Jones U.S. Home Construction ( ITB) was shedding $1.13, or 4.2%, to $25.70. The SPDR S&P Homebuilders ( XHB) was lower by $1.10, or 4.1%, to $25.93. ETFs tracking precious metals were among few winners of a losing session, as gold and silver prices were on the rise. Recently, gold futures were adding $1.10 to $668.80 an ounce, and silver was higher by 12 cents to $13.11 an ounce. The PowerShares DB Silver ( DBS) was adding 26 cents, or 1%, to $25.71. The PowerShares DB Gold ( DGL) gained 29 cents, or 1.1%, to $26.49. The iShares Comex Gold Trust ( IAU) was climbing by 51 cents, or 0.8%, to $66.43. The iShares Silver Trust ( SLV) was up $1.03, or 0.8%, to $130.06.