There is no magic formula but here's an example using negative rates in Denmark: http://www.bloomberg.com/news/articles/2016-05-01/world-s-longest-negative-rate

There is no magic formula but here's an example using negative rates in Denmark: http://www.bloomberg.com/news/articles/2016-05-01/world-s-longest-negative-rate-experiment-shows-perversions-ahead http://www.bloomberg.com/news/articles/2016-05-01/world-s-lo...