How did CalPERS dig a $153B pension hole?

This article is on page A7 of today's Mercury News print edition... but it is not shown on their index pages[1] -- you cannot get to this article except via Search terms.

A related article[2] from a few days ago is visible, though.

[1] http://www.mercurynews.com/opinion/

[2] http://www.mercurynews.com/2017/11/10/borenstein-end-calpers...