But focusing on real variables has failed to explain why interest rates have had little effect on restoring economic stability and, in fact, are contributing now to instability. As interest rates approached the zero bound after 2008, and descended into negative territory in recent years, real economic growth has continued to slow and stagnate nonetheless. No less than $10 trillion in bonds and other securities are now in negative rate territory, with more being considered or on the way. And not only has real economic growth been slowing, but global trade is stalling, productivity has nearly collapsed, real asset investment growth rates are declining, and the drift toward deflation in real goods and services long term continues. Something is wrong with the mainstream theory interpretation of interest rates—as well as the central bankers' policies built upon the theory.