XSO is down 17 points today ( 0.6% )
WMI is up by half a cent today.
holding cash is handy when markets are tanking.
WAM and WAX have outperformed versus the index over past 5 and 10 year periods
despite holding on average over 20% cash.
the XSO has been a dog for a long time. too many small companies are just rubbish quality.
if you want ETF investing I'd use the XJO index.
good luck.