Investors have been hearing for years that interest rates are headed up, even as they have watched them fall to record lows. David Mazza, head of ETF and mutual fund research at SSGA (STT) , said perplexed savers should consider owning the SPDR DoubleLine Total Return Tactical ETF (TOTL) because it looks to balance interest rate risk, credit risk and yield. Oh yeah, it is also managed by the new so-called 'bond king' Jeff Gundlach. 'Jeff Gundlach and his team have proven over the years to have the ability to navigate difficult fixed income markets,' said Mazza. 'And this one that we are experiencing now is probably one of the worst that investors have faced.'