A recently released survey by Bankrate revealed that 66% of Americans with retirement accounts or investment portfolios hadn't touched their investments or adjusted their asset allocations in this period of historic stock market volatility.

Further, the survey of 1,175 investors -- conducted between March 20 and March 24 -- found that 13% contributed more to their accounts and only 11% moved money out of their investments. Millennials were the most likely to have contributed more to their accounts: 24% of them have added funds, compared to 13% of Generation Xers, and 5% of baby boomers. But millennials were also the most likely to have moved money out of stock investments; 15% of them reallocated funds out of equities, compared to 12% of Gen Xers and 8% of boomers.

"Americans are cutting their spending, but they're not bailing on stocks despite an unprecedented drop of more than 30 percent," Greg McBride, chief financial analyst at Bankrate, wrote.

A stock market board with lighted numbers in red and black showing gains and losses.

Image Source: Getty Images.

These are encouraging numbers because while it's unsettling to see the stock market drop so sharply in such a short period of time, it is smart to ride out the volatility and stay invested -- as long as you have a well-considered risk profile. Here are three major reasons why.

No. 1: History is on your side

On Feb. 12, the Dow Jones Industrial Average closed at an all-time high of 29,551. Just over a month later, on March 23, it closed at 18,591 -- down 37%.

But in the two weeks since then, the Dow has climbed back by about 13%, and was as about 21,052 as of Friday's closing bell.

Let's look back at the 2008-2009 financial crisis to see how that played out. On Oct. 9, 2007, the Dow closed at a high of 14,164. It was the start of a year-and-a-half-long stock market decline that bottomed out at 6,547 on March 9, 2009. Over that period, the market lost about 53% of its value.

From that bottom, it took until March 5, 2013 -- when it closed at 14,253 -- for the Dow to get back above its Oct. 9, 2007, high. Investors who were patient through that trough and staying in afterward were rewarded with an extended bull market that saw the market climb to over 29,551 at its peak.

But even when you factor in this most recent downturn, the Dow has returned about 6.7% on an annualized basis over the last 10 years through the market close on April 3.

It's impossible to know if we have hit bottom, but the fact is, the U.S. stock market has endured large drops before, and has always recovered to produce solid long-term returns. 

No. 2: You won't lock in losses

If you move a lot of money out of your stock portfolios now, when the market is near its trough, you are just locking in those losses. Plus, you'll miss out on the gains when the recovery does come.

An analysis by Syfe and CBOE found that those who stayed invested in the S&P 500 throughout the 2008-2009 bear market had more than twice the total return after three years than those who missed the first three months of the recovery, and about a 40% higher return than those who missed the first month of the recovery.

However, it's important to closely review your portfolio to make sure you are comfortable with your risk profile and asset allocation. Also, review your investments to make sure their fundamentals remain solid and their earnings potential is strong. While many companies will be able to weather the storm, some may have suffered more profound, longer-term damage, depending on their industry or circumstances.

No. 3: There are some terrific buys out there

When you see the shares of top companies like Disney (NYSE:DIS), Berkshire Hathaway (NYSE:BRK.A) (NYSE:BRK.B), and Apple (NASDAQ:AAPL), for example, with double-digit-percentage price declines year to date, you know there are great buying opportunities throughout the market.

These, and many other great companies, have been caught up in the selloff or have been hurt by the entirely necessary social distancing mandates in place throughout the country. In many cases, you'll have an opportunity to invest in great companies at prices you'll probably never see again. Take advantage of it.