This Week's ETF Winners & Losers

Health-care and biotechnology exchange-traded funds were among the best performers in the ETF world this week, thanks to positive action from MedImmune (MEDI Quote) and Merck (MRK Quote).

On Thursday, MedImmune jumped 15.3% after it indicated the possibility of a sale of the company. On Friday, Merck jumped 8.3% after lifting its full-year earnings-per-share forecast by 20 cents.

The Pharmaceutical HOLDRs (PPH Quote) ETF was higher for the week by 3.8%, closing at $82.71. The HealthShares Emerging Cancer (HHJ Quote) added 1.2% over the five sessions to end at $27.13.

ETFs tracking metals and mining were also among weekly winners. Gold futures gained roughly 1.5% over the five sessions to close at $689.90 an ounce, and silver futures rose 2.5% to end at $14.09 an ounce.

For the week, the iShares Silver Trust (SLV Quote) was higher by 2.4% to close at $139.90. The streetTRACKS Gold Shares (GLD Quote) ETF added 1.5% to $67.84. The iShares Comex Gold Trust (IAU Quote) tacked on 1.4% to $67.91.

The iShares Dow Jones Transportation Average (IYT Quote) ETF was another of the week's winners. On Monday, rail concern Burlington Northern Santa Fe (BNI Quote) jumped after a Securities and Exchange Commission filing stated that billionaire investor Warren Buffett's Berkshire Hathaway (BRK.A Quote) had purchased a 10.9% stake in the company, making it the largest shareholder.

The ETF, which was also aided by lower crude prices for the week, rose $2, or 2.3%, to $90.10.