WASHINGTON (AP) — Citigroup, Morgan Stanley, UBS and Wells Fargo are paying a total $9.1 million to settle allegations by industry regulators that they sold billions of dollars of volatile investments without properly assessing their risks and whether they were suitable for some retail customers.

Retail customers are individual investors as opposed to institutional investors such as pensionfunds and hedge funds.

The Financial Industry Regulatory Authority, the securities industry's self-policing organization, announced the settlement Tuesday with the four banks. FINRA fined the banks a total $7.3 million and they agreed to pay $1.8 million in restitution to some customers who bought the so-called leveraged and inverse exchange-traded funds from January 2008 through June 2009. The banks neither admitted nor denied wrongdoing.