Brokers prodding individual investors into putting their money into certain key kinds of riskier assets are facing a crackdown from U.S. authorities.
Frontier funds, which focus on up-and-coming emerging markets, and complicated, higher-risk products like exchange-traded funds and mortgage-backed securities are among the products in the firing line of the Financial Industry Regulatory Authority (Finra), the U.S. regulator of securities firms.
(Read more: Investors eye frontier markets in 2014)
"Heightened risks associated with investing in foreign or emerging markets generally are magnified in frontier markets," Finra warned.
Rising interest rates are also worrying the regulator. A hike in interest rates, which were cut drastically then held at historically low levels by central banks like the U.S. Federal Reserve and the European Central Bank after the credit crisis, is looking more likely as markets return to normal.
(Read more: Rising interest rates will be a 2014 theme)
Finra is now targeting those selling interest rate sensitive securities like mortgage-backed securities, the controversial investment products which were partly credited with fueling the credit crisis.
(Read more: Why MBS look good in 2014)
Finra outlined its priorities for investigation in its annual letter to the industry.
"Finra's examination priorities for 2014 provide the industry with a road map of issues that may be of risk to the investing public," Richard G. Ketchum, Finra's chairman and chief executive, said. "By providing clear and detailed guidance to firms, we hope to not only support firms' compliance efforts but also to alert firms to the issues we have identified as the most salient risks to investors and the integrity of our markets."
- By CNBC's Catherine Boyle. Twitter: @cboylecnbc.