ETFs related to oil services were among the strongest performers Thursday, as crude rebounded from six-month lows. Oil was recently up 44 cents to $61.18 a barrel, having reached an intraday low of under $60 a barrel on Wednesday. The Oil Service HOLDRs ( OIH ETF was adding 1.7% to $124.56. The iShares Dow Jones U.S. Oil Equipment Index ( IEZ ETF was gaining 1.5% to $40.48. The Energy Select Sector SPDR ( XLE ETF was higher by 1.3% to $51.55. In addition, other commodities were moving to the upside. The iShares Silver Trust ( SLV - Get Report) ETF was recently up $2.62, or 2.4%, to $111.48, and the iShares Comex Gold Trust ( IAU ETF was tacking on 68 cents, or 1.2% to $57.98. The PowerShares Lux Nanotech ( PXN ETF was one of the worst losers Thursday, due to a 24% plunge in holding Nucryst Pharmaceuticals ( NCST. Shares fell after the company announced a trial for its eczema cream failed. The ETF was lower by 36 cents, or 2.1%, to $17.18. The Internet Infrastructure HOLDRs ( IIH ETF was also trading lower. Late Wednesday, holding InfoSpace ( INSP warned about revenue, dropping the shares by nearly 21%. The ETF was down 13 cents, or 2.4%, to $5.36. Retail ETFs followed CVS ( CVS - Get Report), Walgreen ( WAG and Rite Aid ( RAD - Get Report) lower after Wal-Mart ( WMT - Get Report) introduced a pricing plan for substantial discounts to generic drugs. CVS dropped 8.7%, Walgreen fell 6.7%, and Rite Aid lost 6.3%. The Retail HOLDRs ( RTH ETF was falling by $1.86, or 1.9%, to $96.88. The PowerShares Dynamic Retail ( PMR ETF was recently lower by 26 cents, or 1.4%, to $17.82.