Gensler has developed a reputation as a tough regulator who also was a successful leader on Wall Street.

But how a Democratic-led SEC interprets and enforces Reg BI depends on its chair.

Industry officials of all stripes continue to scratch their heads about the term as they attempt to comply.

The future of investor protection hinges largely on who wins the next Presidential election.

CNBC profiles the impact of Reg BI on sales, advice, and investors themselves.