Over half of US investors plan to invest in exchange traded funds, or ETFs, in 2017. And like with most trends, millennials are leading the pack.

That's according to a new survey released by $5.1 trillion dollar investment manager BlackRock on Wednesday.

The survey found that more millennials (defined as age 21-35) are invested in ETFs than members of Gen X (age 36-51), Boomers (age 52-70), and Silvers (age 71-75).

The BlackRock ETF Pulse Survey, which polled 1,001 investors and 409 financial advisors, revealed that 70% of millennial investors plan to invest in ETFs in the next 12 months compared to 52% of total investors.

A greater percentage of millennials also took steps to learn about ETFs in 2016 and a greater percentage plan to learn about ETFs in 2017.

According to BlackRock, ETF investors tend to be younger, more active in the markets, and more engaged in managing their finances. They are also more confident and optimistic about their financial futures than the overall investment population.

BlackRock's head of US iShares Martin Small told Business Insider that there are a few reasons that millennials are driving this trend.

First, millennials like being able to access high-end goods at reasonable prices, Small said. He likens millennials buying ETFs to the popularity of Uber, which provides access to an exclusive private car service at a reasonable rate.

"I think millennials are driving a big portion of ETF adoption because they like self service, and they can go on their Fidelity account and buy more than 70 iShare ETFs," he said. "They can access the market in the same way that the most professional, largest, technologically enabled investor can access it."

Secondly, millennials carry with them the mental scars of the financial crisis in 2008. "They have internalized deep into their brains the idea that it is important to build diversified portfolios."

The survey data shows that 42% of ETF investors use the investment product to replace choosing individual stocks and to provide broader, more diversified exposure.

Finally, Small sees millennials as "one of the most savvy generations" when it comes to comparative price shopping.

"I think of the millennial generation to be deep value shoppers," he said. "When they think of the combined value sitting in ETFs - low cost, extremely tax efficient, big, broad market exposure - they see something that is high quality and a real bargain compared to other ways of investing."

What's needed now is more ETF education, according to Small. "We need to provide more education about ETFs generally... We have to continue to work with them on the ability to navigate what is a big product landscape on how they can make the best decisions for their own portfolios."

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