The effective duration of his fund somehow fell to minus 4.58 years at one point, even though the prospectus on Janus’s website says the “fund’s https://www.bloomberg.com/opinion/a...y-tale-for-any-future-bond-kings?srnd=premium please explain now this is possible.
Possibly, he was short treasuries. Also he is well known to juice his returns by selling calls. Probably he overwrites his call options and market rallied, effectively became short.