Commentary Central banks should know by now that you cannot have negative interest rates with low bond yields and strong growth. One or the other. Central banks have chosen low bond yields at any cost, despite all the evidence of stagnation ahead. This creates enormous problems and perverse incentives. It’s not a surprise that markets have bounced aggressively, driven by the tech sector, after a slump based on concerns about the pace of economic growth. Stimulus package effects are increasingly short, and it was pretty evident in the poor figures of industrial production and the ZEW survey gauge of expectations. The same can be said about a weakening Institute for Supply Management (ISM) index in the United States. The U.S. ISM Services Purchasing Managers’ Index (PMI) came in at 60.1, below expectations (63.5) in June, precisely in the sector where the recovery should be strongest. Interestingly, European markets declined sharply …