Alex, here is one academic research paper from 2018 (two years ago) detailing ensemble methods in portfolios.

https://papers.ssrn.com/sol3/papers.cfm?abstract_id=3243974

The research behind the paper, followed by the peer review, was likely in 2017 if not earlier.

This was the first one that appeared in a quick search (most popular? Most links / references?) not necessarily the first published. Even if it was first, it’s still several years old.

My criticism was directed at CFA institute, which purports to keep its members up to date on the latest financial developments. I continue to be disappointed when I read topics in CFAI publications that were discussed elsewhere several years before