Knowledge among investors in the U.S. is generally low, according to new research from the investor education arm of the U.S.-based Financial Industry Regulatory Authority (FINRA).

Two-thirds of respondents in a survey of 2,000 U.S. investors couldn’t pass a 10-question quiz on investment concepts, the FINRA Investor Education Foundation reported.

For example, the survey found that almost half (46%) think that past performance is a good indicator of future results. It also found that only 30% know that the main advantage of index funds over actively managed funds is that they typically charge lower fees and expenses.

Investor knowledge was particularly weak when it comes to understanding industry fees.

The survey found that nearly one-third don’t know how much they pay in investment fees and expenses, or believe that they don’t pay anything at all.

It also found that investors are highly confident in their own portfolios, with 29% saying they expect their portfolio to outperform the market, compared with just 4% who expect it to underperform.

Regarding cryptocurrencies, most investors (85%) said that they are aware of crypto, and 12% said that they have already invested in crypto.

The study also found that investors increasingly prefer to receive investment disclosure via email (33%), while a preference for mailed disclosure dropped from 49% in 2015 to 36%.

“These research findings underscore the need for researchers, policy-makers, advocates and industry stakeholders to continue to develop innovative investor tools and resources to better educate investors and to help protect them from fraud,” said Gerri Walsh, president of the FINRA Foundation and FINRA’s senior vice president for investor education.