Here they are, in order, from DB

1. Continued increase in wealth inequality, income inequality, and healthcare inequality

2. Phase one trade deal remains unsigned, continued uncertainty about what comes after phase one

3. Trade war uncertainty continues to weigh on corporate capex decisions

4. Ongoing slow growth in China, Europe, and Japan triggering significant US dollar appreciation

5. Impeachment uncertainty & possible government shutdown

6. US election uncertainty; implications for taxes, regulation, and capex spending

7. Antitrust, privacy, and tech regulation

8. Foreigners lose appetite for US credit and US Treasuries following Presidential election

9. MMT-style fiscal expansion boosts growth significantly in US and/or Europe

10. US government debt levels begin to matter for long rates

11. Mismatch between demand and supply in T-bills, another repo rate spike

12. Fed reluctant to cut rates in election year

13. Credit conditions tighten with more differentiation between CCC and BBB corporate credit

14. Credit conditions tighten with more differentiation between CCC and BBB consumer credit

15. Fallen angels: More companies falling into BBB. And out of BBB into HY.

16. More negative-yielding debt sends global investors on renewed hunt for yield in US credit

17. Declining corporate profits means fewer dollars available for buybacks

18. Shrinking global auto industry a risk for global markets & economy

19. House price crash in Australia, Canada, and Sweden

20. Brexit uncertainty persists

Some of these seem get trotted out every year (and more often than that). Dunno what the story is with 13 and 14. Double trouble? ;-)