Even if the stocks are similar, ETFs can behave differently. In funds weighted by market cap, bigger companies have more sway. In equal-weighted funds, all companies have the same impact. They'll do better when the smaller ones shine.
SPDR S&P Biotech (XBI)
Powershares Dynamic Biotech & Genome Portfolio (PBE)
First Trust Amex Biotechnology (FBT)
iShares Nasdaq Biotechnology (IBB)
Biotech HOLDRs (BBH)
Year-to-Date Return (%)
Number of Stocks
How Stocks are Weighted
Top Three Holdings
Myriad Genetics, Cepheid, Pharmion
Imclone Systems, Gilead Sciences, Amgen
Vertex Pharmaceuticals, Biogen, Celgene
Amgen, Gilead Sciences, Celgene
Genentech, Amgen, Gilead Sciences
Top Three as a %
Avg. Market Cap ($billions)
This index starts with every biotech in the S&P universe, then trims the list based on market cap and trading volume.
Powershares uses its own "Intellidex," choosing stocks by such criteria as growth rate, risk, and valuation.
With FBT, you know what you're getting: 20 top biotech stocks with very little turnover.
The clear leader in trading volume, iShares contains nearly every biotech-related stock in the NASDAQ.
This portfolio is never reweighted, and its stock holdings rarely change.
All data Oct. 1 Data: ETF sponsors, businessweek.com
By Ben Levisohn