The approach for many of these funds is to start with a broad market index (say the Russell 3000), then calculate factor scores along the 5 indentified factors. With these factor scores, the manager can then formulaicly weight each company in the index by their factor score to form the portfolio. Then every three to six months or so, the factors can be adjusted and the portfolio can be rebalanced.
Oppenheimer Russell 1000 Dynamic Multifactor ETF (OMFL) charges 0.29%
PIMCO RAFI Dyn Mlt-Fctr Emrg Mkts Eq ETF has seen massive growth in AUM from inflows – it is now 385million and was just 23 million in assets back in October 2017
iShares Edge MSCI Multifactor USA ETF just breached the 1 B in AUM in February 2018 and was at 333 milion in assets in February of 2017 (200% growth in 1 year)
PIMCO Launches Dynamic Factor Funds
http://www.etf.com/sections/daily-etf-watch/pimco-launches-dynamic-factor-funds?nopaging=1
OppenheimerFunds Announces New Dynamic Multi-Factor and Single-Factor Based Strategies