As the bull market heads into its ninth year, the list of potential risks that could stop its run is growing.
The wall of worry starts in Washington, but the sources of potential risk come from around the globe — including North Korea, China and the Middle East.
Domestically, the Alabama U.S. Senate vote this week suggests that the 2018 midterm elections may not go smoothly for congressional Republicans and President Donald Trump as they try to hold onto the GOP majority next year. That threatens the Republican agenda and makes it possible that the tax reform vote, expected next week, could be the final big GOP initiative to make it through Congress.
"I think the most enduring risks that investors face tend to come from domestic forces," said Marc Chandler, head of foreign exchange strategy at Brown Brothers Harriman.
On the geopolitical front, markets could face bouts of nervousness in the new year as the Trump administration is forced to find a way to deal with North Korea's nuclear ambitions, which increasingly threaten global security.
However, there is a solid list of positives, and analysts expect another up year for the market in 2018, but with more modest gains. Strong earnings growth, a new corporate tax plan and a stronger global economy should help provide fuel for the bull market for another year. CNBC's survey of Wall Street strategists shows a median forecast of 2,800 on the S&P 500, a gain of about 5 percent from current levels, versus 2017's 20 percent gain.
The economy and market are heading into late cycle, which should be a good period for both.
"You have the possibility of a record-long expansion," said Steven Wieting, chief investment strategist at Citi Private Bank. He said there are "the seeds of a decent late-cycle environment which is not producing any signs of future catastrophes so far. We should enjoy these."
Yet, for all the good news there are a few potential time bombs for markets.