But with the rise of ETFs in the s, investors were given a rapidly expanding choice of diversified investments. Why Fidelity. In an expanding economy, riskier sectors may tend to rise while more conservative sectors lag; conversely, in economic contractions or recessions, riskier sectors may struggle while more conservative sectors make gains. Research Sector and Industry Performance Get the latest news and analysis for sectors and industries. Brandt, and Kenneth A. ETF shares are bought and sold through exchange trading at market price not NAV , and are not individually redeemed from the fund.