Increased concerns about the outlook for global economic growth and about numerous geopolitical events deflated global stock markets and benefited mortgage rates this week. However, the latest news on the trade talks between the U.S. and China mostly offset this, and rates ended another volatile week just marginally lower. 

Investors face a lot of significant questions on a wide range of issues right now, and it's no surprise that they have responded to the increased uncertainty by reducing the level of risk in their portfolios. As usual, their primary method to accomplish this has been to shift assets from stocks to bonds, including U.S. mortgage-backed securities (MBS). 

The trade tensions between the U.S. and China remain one of the largest sources of concern for investors, because tariffs and other barriers to trade slow global economic activity. The biggest news on this front this week was the announcement that the U.S. will delay until December 15 tariffs on some goods that had been scheduled to be imposed on September 1. 

The outlook for global economic growth is another big question mark for investors. Around the world, recent data clearly indicates that the manufacturing sector has taken a hit from trade issues, and business investment has fallen as companies hesitate to make long-term capital commitments. On the other hand, consumer spending has generally remained healthy. In the world's second-largest economy, for example, Alibaba ("the Amazon of China") just released strong earnings results.