In the Canadian press, this is attributed to inverted yield curve, resulting from the trade war.
> Anyone buying that bond is willingly buying an investment that's guaranteed to lose money, but investors are more than happy to buy it up - because the fear is that alternative investments will fare even worse. [....]
> Those negative yields are filtering down into the economy in some truly jaw-dropping ways. A Danish bank this week started offering a negative yielding mortgage ...
"Free mortgages and bond yields turned upside down: trade war impacts veer toward the wacky" Aug. 17, 2019 https://www.cbc.ca/news/business/trump-trade-war-impacts-1.5247996