There are two questions hiding in this one.
Is the account safe? Yes. The money you put in is yours. It does not belong to your employer, and a falling market does not take your shares away.
Is the balance safe from dropping? No. If your 401(k) holds stock funds, the balance will fall when stocks fall. That is not a malfunction. It is what stocks do.
Since 1928, the S&P 500 has finished the year down 26 times out of 98. Roughly one year in four. Any plan that lasts decades has to pass through many of them.
So the useful question is a third one.
When do you need the money?
Ten or more years away. A crash is uncomfortable and, for you, mostly good news. Every paycheck is buying shares at lower prices. The drop that matters is the one that happens right before you spend the money, and that is not this one.
Five to ten years away. This is the time to look at your mix, calmly, before anything happens. Not to get out of stocks, but to make sure the amount in stocks matches the amount of drop you could live through.
Retiring within five years, or already retired. This is where a crash does real damage, because you are selling shares to live on while prices are low. Those shares are gone when the recovery comes. It has a name: sequence of returns risk.
What actually protects you
Not predicting the crash. Nobody can do that reliably, including me.
What protects you is having the money you will spend in the next few years somewhere that does not fall with the stock market. Then a bad year in stocks is something you watch, not something you sell into.
For someone still working, the paycheck plays that role. For someone retired, it has to be built on purpose.
The mistake that makes it permanent
A falling balance is a loss on paper. It becomes a real loss at the moment you sell.
The lasting damage rarely comes from holding through the drop. It comes from moving to cash near the bottom and waiting for things to “settle” before getting back in. Things tend to settle at higher prices.
If you feel that pull, you are not weak. You are normal. The fix is to decide what you will do before it happens, while you are calm. That is The Crisis Script.
A falling balance is weather. Selling at the bottom is the damage.
What to do this week, whatever the market is doing
Look at how much of your 401(k) is in stocks. Most plan websites show it on the first page.
Picture that part cut by a third. Say the dollar figure out loud.
If you could carry on with your life, your mix is probably fine. If that number would force you to sell or to delay retirement, adjust now, in calm weather, not during the storm.
Keep contributing either way. And never give up the employer match.
If it is already falling
Do not look at the balance every day. Checking more often does not give you more information. It gives you more chances to act on fear.
If you are still frozen, I wrote a page for exactly this morning: the market is scaring me.
Related questions: are target date funds good, the cost of too much cash, what to check when your advisor is losing money and should I roll my 401(k) into an IRA.
One question for this week: in what year will you first need to take money out of your 401(k)? Everything else follows from that date.
As always, if you want to talk any of this through, the door is open. Genti