The market’s long winning streak has investors wondering whether a crash is waiting in the wings. Don and Tom look at the S&P 500’s run, the lost decade that followed the 1990s boom, and why international diversification changed that outcome dramatically. They also explain why market timing asks the impossible: missing the worst days sounds wonderful, but missing the best days can be devastating. The less theatrical answer is still the useful one—make a plan, understand your tolerance fo...