The following commentary comes from an independent investor or market observer as part of TheStreet's guest contributor program, which is separate from the company's news coverage.NEW YORK ( ETF Expert) -- The iShares 20+ U.S. Treasury Bond Fund ( TLT) has often exhibited wider daily trading swings than the S&P 500 SPDR Trust ( SPY). This quirk alone has made it difficult for me to embrace the long end of the Treasury bond curve. Instead, I've been more apt to stick with intermediate investment-grade corporate credit, as well as short-term and long-term high-yield corporate bonds. Granted, governments and central banks can print paper or create an electronic equivalent out of thin air. Yet corporate balance sheets also benefit when a central bank pursues an "easy money" policy.