24-year-old David Sotolotto likes wearing Nike shoes when he runs, and his favorite fast food is Taco Bell.

It turns out, the first stocks he invested in were Nike Inc. NKE, -1.46% and Yum! Brands YUM, -1.70% .

His story is not uncommon for young investors.

“Young people have more brand familiarity with companies like Amazon, Google, Twitter,” said TD Ameritrade Managing Director of Trading Nicole Sherrod. “For retail investors in general, regardless of their age, they tend to invest in what they know.”

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Sotolotto worked a job at drug store chain Walgreens in high school and had some money saved up, which he knew he would invest.

“I noticed that Nike had dropped $9 in one day,” he said. “I jumped on them at that point. I figured it’s a big company. It’s not going to be a case of catching the falling knife.”

He invested in 2011, when he was 20.

Stocks first traded by boomers and millennials

Boomers Millennials Symbol % of first stock trades Symbol % of first stock trades Apple 3.7% Apple 6.3% General Electric 2.9% General Electric 3.0% Facebook 2.6% Bank of America 2.9% Cisco 2.3% Ford 2.4% Microsoft 2.2% Microsoft 2.1% Bank of America 2.0% Intel 1.5% Intel 1.8% Cisco 1.4% Alcatel-Lucent 1.6% Facebook 1.2% Pfizer 1.0% Google 1.2% AT&T 0.9% Disney 0.9% Source: TD Ameritrade

“We do see a lot of people investing in Disney as one of their first investments,” Sherrod said. “Parents who have young children buy that stock as one of the first positions. It’s a company that young people have a tremendous amount of familiarity with.”

As the older generations pick stocks, they consistently invest more often in healthcare companies.

“The main difference is that the different demographics know different companies,” Sherrod said.

Meanwhile, younger generations show a preference for technology and other innovation-oriented companies.

Boomers vs. Millennials: What to Invest In

“They tend to be more socially responsible, caring more about the environment,” Sherrod said. “Electric cars are a great brand: good for the environment and sexy as well.”

It wasn’t until after Sotolotto took a personal finance course that he started investing in companies that weren’t just brands he knew.

“That taught me more what to look for in terms of the financials of stocks,” he said. “That got me into looking at companies I hadn’t heard of.”

Top 10 stocks for boomers and millennials

Boomers Millennials Stock % of Equity Portfolio Stock % of Equity Portfolio Apple 9.0% Apple 11.4% General Electric 1.7% Facebook 2.6% Intel 1.6% Bank of America 2.0% Bank of America 1.6% Berkshire Hathaway 1.7% Microsoft 1.5% General Electric 1.6% Facebook 1.4% Alibaba 1.5% AT&T 1.3% Tesla 1.3% Berkshire Hathaway 1.2% Microsoft 1.2% Exxon Mobil 1.2% Intel 1.1% Johnson & Johnson 1.0% Exxon Mobil 1.0% Source: TD Ameritrade

Apple is widely held across TD Ameritrade’s whole customer base, which follows the trend of brand familiarity, where people invest in products they use.

“Even though Android has a greater overall market share than Apple in terms of phones, 75% of our trades go through an iOS advice,” Sherrod said. “When it comes to investing in what you own, that holds true here.”

It’s not just what millennials are investing in, but how they’re investing.

More young people are opting to put their money in robo-adviser startups like Wealthfront and Betterment.

Schwab launched its Schwab Intelligent Portfolios in March, and Vanguard has already attracted more than $4 billion to its robo-adviser offering, according to a MarketWatch article.

And venture capitalists seem to like the robo-adviser startups too. Wealthfront raised $64 million in October 2014, bringing its total funding to $130 million. Personal Capital has received $104 million in funding.

The startups may be appealing to the generation saddled with record student loan debt because of low-fee models and ability to manage smaller portfolios. It also may be because investing with robo-advisers is seen as minimal effort to web-savvy investors, where investors handle all transactions online and never speak with a real person.

“Millennials want to focus on things like their career, friends and family,” said Wealthfront CEO Adam Nash. “While they know managing their money is important, they don’t want to spend time watching their investments every day. They want to “set it and forget it” and trust technology to watch over their investments 24/7.

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Wealthfront requires a $5,000 minimum investment and manages your first $10,000 for free. Betterment has a $0 minimum account balance.

Wealthfront’s average client is under 35, while Schwab’s average client is in their 50s, Nash said.

“Schwab grew up with the baby boomers and as such, they have rolled out services to cater to this demographic who have a much different set of concerns from the millennial investors,” he said.

Still, robo-adviser startups are tiny compared to the big players like Schwab or Vanguard. Where Wealthfront handles $2 billion in client assets, Schwab handles $2.53 trillion in client assets.

Still, robo-advisers like Wealthfront and Betterment anticipate they will keep growing as more young people invest.

“Our growth in the last three years has been explosive and it’s directly connected to our focus on millennial investors,” Nash said.