The current month spanning tree is possibly one of the cleanest such trees I have seen, as a number of points are quite readily made about the current volatile market. 

1. Raw dollar flow and liquidity changes have resulted in the S&P and the Russell being most correlated. 
2. As the current crisis is one of a financial nature, the least secure asset, the Russell, is most correlated to XLF.
3. Healthcare (XLV), Consumer Staples (XLP), and Utilities (XLU) are on one chain of more stable asset classes.
4. Consumer Discretionary (XLY) drives factory (XLI) and resource (XLB) utilization and technology (XLK) demand and sales.
5. Energy (XLE) stands apart from other sectors of the economy in a crisis.

Week Minimum Spanning Tree

Month Minimum Spanning Tree