FYI: Factors are everywhere these days. In the ETF world, factor strategies are not only growing in number, but in assets, as more and more investors look to capture various return streams beyond plain market beta.
Factors are equity risk premiums that historically have delivered outsized returns over time relative to the market.
Regards,
Ted
http://www.etf.com/sections/features-and-news/behind-factor-etfs-popularity