This is something I'd keep my eye on:
http://www.reuters.com/article/us-globa ... SKBN19L04PIt's a bit volatile and yes, is subject to influence from Central Banks but the dollar really isn't holding its ground anymore. Value has been steadily dropping while the Pound and the Euro continue to ascend on the backdrop of rising interest rates due to inflationary pressures from economic growth. The US Central Bank likely won't raise rates again this year and that's a pretty clear indication that they don't expect growth to go much further. Market's are taking notice of how f**k up this administration really is. This all on the back of Trump sanctioning a Chinese bank and some officials that launder money and ship supplies to the DPRK as well as while the US agrees to ship $1.3 billion in arms deals to Taiwan. It's important to note that on its own arms deals with Taiwan aren't new or unique - been done under several administrations. But this is quite a bit of action all at once and could provoke a more coordinated effort from China in the future (Xi Jinping really doesn't have to quabble with any legislative bodies to get what he wants - and the Politburo Standing Committee is made up of seven people...as opposed to our 535 in the legislative branch alone). Furthermore, while we only import a small percentage of our steel from China more tariffs on there could easily be seen as an added affront.
Overall, I think investors are starting to doubt sustained or increased US growth in the short to medium term. Infrastructure and tax breaks have already been delayed.