If you have young clients in your book, you’re not charging them enough.

So finds a study by PriceMetrix, released today.

Advisors are discounting their equity trade commissions by 36%, on average, even though clients aged 20-to-39 have fewer assets and trade less. That’s the highest discount among all age groups.

Read: Don’t be too quick to discount

And those discounts don’t breed loyalty. Young investors close their accounts more often than any other age group: 17% of accounts that were open at some point during the study’s 12-month measurement period closed by the end.

“This suggests the opposite of what many advisors believe — that attracting clients when they are young means they’re going to stay and grow with you,” says the study.

“Rather, what our data shows is that whether it’s your decision or theirs, your young clients are actually more likely to leave than others, even though you’d expect the rate of closure to be the lowest of any age group.”

Read: How to spot high-potential clients

Young investors are more price sensitive than older ones, the study adds. “It may be the case that with a smaller portfolio size, they are simply unable to take full advantage of the value proposition of a full-service investment advisor.”

Young clients constitute 8% of the typical North American book of business. Fifty-two percent are between 40 and 64 years old, and 40% are 65 and older.

Advisors licensed less than three years have a higher proportion of investors aged 20-to-39 in their books. There is little difference in the age distribution of large and small producers’ books.

Read: Five pieces of advice for young clients and prospects

“As advisors patiently wait for their young clients to accumulate more wealth, they should ask themselves if it’s worth it.”