You’ve reached your emergency fund savings goal, and have the capacity to continue saving even more.

Where should you put the money?

For younger investors, it’s especially important that they’re putting some of their longer-term savings into the stock market. With years and even decades until they need that money, they stand to gain the most from such investments.

However, investors in their 20s may actually be playing it too safe, a recent survey found. This age group has more than 28% of its wealth in cash, according to a survey from financial services company Personal Capital. That is more than any other age cohort apart from retirees in their 80s and 90s, who are holding 29% and 31% in cash, respectively.

“Sometimes instead of putting a plan in place, it’s easier to not think about it,” said Michelle Brownstein, a certified financial planner and senior vice president of Personal Capital’s private client group.

Need for education

Younger people, especially those just starting out, may not understand how they should be investing in the market, according to Brownstein.

A lack of awareness, especially for long-term goals such as retirement, may mean younger people are leaving money on the sidelines, she said. Some are diligent savers but miss the next step of how much they should be contributing to investment accounts such as an employer-sponsored 401(k), an individual retirement account or even a brokerage account.

In addition, this age group may be juggling financial goals that compete with retirement, such as paying off student loan debt, buying a house or even getting married.

More from Invest in You:
10 work-from-home jobs that pay six figures
If you plan to quit, here’s what career experts say you should do
Has the 4-day workweek’s time come? Some predict it will catch on

Of course, it is important to have a emergency fund, something that many have found is even more of a priority after the coronavirus pandemic. Generally, personal finance experts recommend having three months to six months — or even longer — of living expenses in cash in case of an emergency.

But, if you have met that goal and are continuing to save, that extra money should be going into an investment account, according to Brownstein, especially if you don’t plan on needing it for anything in the next few years.

“If it’s not cash they need in the next 18 months, it should be invested,” she said.

The power of the stock market

Investing in the stock market is one of the best ways to build wealth. By keeping too much cash on the sidelines, younger investors could miss out on years of healthy returns that would benefit them in the long term.

That’s because the longer you have for your money to compound — basically, your interest earning interest — the more you will accumulate even if you start with a modest amount.

“The other good thing about investing in the stock market is that it’s relatively easy,” said Roger Ma, a CFP at lifelaidout in New York and author of “Work Your Money, Not Your Life,” adding that options such as target-date funds and index funds help simplify the process.

Any retirement fund offers these choices, from an employer-sponsored 401(k) to a Roth IRA.

Even those without employer-sponsored retirement plans can invest with little to no cost, said Ma. There are many low or no-cost brokerage options that almost anyone can access to begin buying stocks, and some mutual funds and exchange traded funds have zero expenses, he said.

It’s important to have long-term savings growing because if you aren’t earning returns on the money, its buying power will be eroded by inflation over time, according to Lauryn Williams, a CFP and founder of Worth Winning in Dallas. That means that as costs rise, you’ll need to save more and more to be able to afford the same things, she said.

“If you instead put your money into the market now, you can start to earn an additional amount above and beyond,” she said.

Getting on the right track

If you aren’t sure that you’re saving and investing enough for retirement or your other future goals, there are a few things you can do to assess your situation, according to Brownstein.

First is making sure you have an emergency fund that you’re comfortable with, she said. Then, ensure you’re taking advantage of any match your employer offers for contributing to a retirement account, if you have one.

“If you aren’t putting in enough to get the match, you’re leaving money on the table,” she said.

Then, she recommends taking the time to educate yourself on saving and investing, and either coming up with your own game plan to meet your goals or seeking guidance from a qualified financial advisor.

“Not knowing how to do something means I should work on it and learn it,” she said. “No one else is going to make sure you have enough for retirement — that’s on all of us.”

SIGN UP: Money 101 is an 8-week learning course to financial freedom, delivered weekly to your inbox.

CHECK OUT: How to make money with creative side hustles, from people who earn thousands on sites like Etsy and Twitch via Grow with Acorns+CNBC.

Disclosure: NBCUniversal and Comcast Ventures are investors in Acorns.