How low can the Fed go? In a global game of interest rates that have dipped below zero for the European Central Bank (ECB), France, Germany, and Japan, there's always more room to fall. Negative interest rates have become a regular feature of much of the world's economy. Central banks have gone negative to prime their nations' economies. Make investors take a loss to park funds someplace safe, so the theory goes, and they will get those dollars—and euros and yen and everything else—into circulation, jump starting spending and the economy. And it could happen here. "There is no barrier for U.S. Treasury yields going ... (full story)