Stocks and bonds delivered spectacular performance in the first six months of 2019. The S&P index of large-cap U.S. stocks returned 18.5% for the year through June 30, while the Barclays Aggregate index of investment-grade bonds delivered an equally impressive 6.1% return. Declining interest rates—sparked by the Federal Reserve—deserve most of the credit for the impressive performance. But what should we expect for the second half of 2019? On the one hand, economic growth in the U.S. remains reasonably healthy, if not robust. And yet there are several material risks which could spook investors over the thinly-traded summer months.