In the current environment, they could buy US treasuries instead of invest in nations with negative rates.

And this is critical, so the money does not just evaporate (as we have whitnessed in Milwaukee the last years).Here is the official website of the US Treasury including an interactive map.

I know they only plan to raise 1/4 point, but mortgage rates key off the treasury bonds which move independent of the fed.

When rates go up the risk free rate of return (type of treasury bill or bond backed by US Govt) will rise would want your risk adjusted rate of return to increase based on the same risk premium.To put in English, if the risk free rate of return went from 1.5% to 4% and you had a 8% return (8-1.5 is 6.5% risk premium).

The typical pricing for lowest possible risk is treasury bonds ("backed by full faith and credit" ahem...).

The Treasury Regulations clearly  indicates that an investor must have the intent to hold the  Relinquished Property and  the Replacement Property for rental, investment or business use. 

Returns will vary with the level of risk - for example if there was a "crypto currency fund" that targeted 15% or a US Treasury Fund targeting 4%, most would be like of course 15%, but risk is also a major key component. 

I would invest in risk-free online savings, CDs, US Treasuries, and money market mutual funds at 5% over getting 10% in asset classes that have a risk component. 

Typically, commercial reset rates are tied to the 10 year treasury.  

And the rest cash out and go into stocks (gradually, dollar cost average to minimize risk), safe savings/treasuries, and some maybe in private RE syndications.