There really is no such thing as a free lunch, a new study suggests.

Investment seminars offering attendees a free lunch or dinner are a common setting for fraud, says the American Association of Retired Persons, Washington, which conducted the study. Sponsors of such seminars typically offer means to attract investors who are near retirement age, the group notes.

Of survey respondents who had attended a seminar, more than 78% said they had gone expecting that the financial discussion would be a chance to learn more about financial issues. Once at the seminar, however, half said the presenter asked them for personal data, such as their contact information or details about their finances.

And 46% reported the seminar presenter attempted to make a follow-up appointment at their home. Nearly 40% reported that the presenter tried to sell them financial products either during or after the seminar.

According to AARP, about 6 million Americans age 55 and older have attended a free lunch or dinner in the past 3 years. Mailed invitations were the most common method of solicitation, reported by 63%, and 27% reported receiving at least 10 invitations.

The survey was conducted by phone Aug. 19 through Sept. 3 among more than 1,000 financial decision makers aged 55 and up.

AARP has been monitoring free-lunch seminars for over a year in cooperation with the North American Securities Administrators Association, Washington, using volunteers who attend the seminars and report what they heard.

According to AARP, volunteers reported many of the seminars focused on different kinds of annuities, and 39% reported being encouraged to buy an annuity. Nearly half said that the speaker did not discuss the risks associated with the annuity. Seminar speakers consistently promised that products were low risk or that they would yield high rates of return, according to AARP.

“Low risk, high reward is a red flag warning for possible investment fraud,” said Denise Voigt Crawford, NASAA president and Texas Securities Commissioner, commenting on the reports from AARP’s volunteers.