By Sarah N. Lynch

WASHINGTON (Reuters) - A top regulator on Tuesday said the Securities and Exchange Commission will bring more enforcement actions against companies selling complex securities and risky structured products to retail investors.

"An investor's constant quest for the next big thing plays right into the hands of fraudsters, who often use the complexity of new products to hide their schemes," said SEC Democratic Commissioner Luis Aguilar, in prepared remarks for the annual North American Securities Administrators Association conference.

In the aftermath of the 2007-2009 financial crisis, the SEC created a series of units dedicated to conducting probes in particular specialized areas.

The Complex Financial Instruments Unit is devoted to probing cases involving complicated securities products.

That unit brought a number of cases against big banks that were alleged to have misled more sophisticated investors in complex structured products, such as collateralized debt obligations.

Aguilar noted that now, the unit is devoting more resources to complex products that are being marketed to less sophisticated retail investors.

Examples of such products, he said, include equity-indexed annuities, leveraged and inverse exchange-traded funds, reverse convertibles, alternative mutual funds, and structured notes - a product that contains characteristics of both bonds and derivatives.

Structured notes, he noted for instance, contain complex pay-off structures and opaque pricing, and their issuance has been growing since the crisis.

"The commission expects future enforcement cases in this space," he said, adding that compliance examiners are also actively focused on complex products being sold to mom-and-pop investors.

Aguilar said Tuesday that more needs to be done than just going after bad actors who may dupe unsuspecting investors.

He said that some have accused the SEC of failing to do enough to beef up disclosures surrounding these products, and he agrees more steps should be taken to help them understand these products.

"These concerns are valid and deeply troubling," he said.

He noted that the SEC has focused a lot on structured notes disclosures, but that it should expand to look at disclosures of all complex securities sold to the general public.

(Reporting by Sarah N. Lynch; Editing by Lisa Shumaker)