While that rate of trading was easily the highest for 2016 — trading on the heels of this year's Brexit vote was the second highest — Rob Austin, director of retirement research at Aon Hewitt, notes that the vast majority of participants stayed put.

In terms of the absolute value of assets, 0.10 percent of all assets tracked by the record keeper were traded the day after the election. The daily 12-month trailing average of 401(k) assets traded is 0.02 percent.

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Aon Hewitt tracked high levels of trading volume in the days before the election. On November 1^st, a week before election day, volume was normal, with only 41 percent of traded assets moving from equity holdings to fixed income.

But the ensuing four days saw a steady uptick, as the participants who did move assets directed savings to fixed income. The day before the election, trading volume was 3.24 times a typical day, with 84 percent of traded assets moving to fixed income.

On election day, volume moderated to 1.66 times the average, with 96 percent of trades moving assets to fixed income.

The post-election spike in trading came after a night of tumult in equity futures markets.

On the day of the election, the Dow Jones Industrial Average closed up 0.4 percent.

But as returns from the polls showed candidate Trump was performing better than expected, futures markets began to react negatively.

As a Trump victory became more likely, DJIA futures markets tumbled about 800 points. At one point trading on the NASDAQ futures market was halted.

Futures markets recovered off those lows, and ultimately, the DJIA closed up about 257 points the day after the election.

While trading was small in terms of absolute volume of assets in the Aon Hewitt universe—the firm's index tracks about 1.3 million participants and $150 billion in savings—Austin says the activity leading up to the election, and the record volume the day after, is telling nonetheless.

"Most participants understand that markets in general don't like uncertainty," said Austin. "Clearly the markets became comfortable with the prospect of a Trump administration."

Participants too seemed to adjust quickly. By Friday of last week, trading in 401(k)s had normalized, as equity markets closed out the week with further gains.

For participants who may have been acting out of fear on the election's result, Austin says there are some potential takeaways from last week's trading spike.

"It's really difficult to sell stocks when they go up, and much easier to sell stocks when they go down," he said. "The objective is to always try to take the emotion out of planning for retirement through a 401(k). Last week could make the case for a disciplined automatic rebalancing approach, or for putting those decisions in the hands of professionals—either in a TDF or a managed account."

Over recent years, the trend of trading in 401(k) plans has subsided as more participants are invested in target-date funds, said Austin. Aon Hewitt's index does not break out the traded assets that may have been in TDFs. "It's possible that some actively managed TDFs actually took opposite positions from the election night volatility. Some may have seen the drop as a buying opportunity."

Nor does the Aon Hewitt index separate trading in managed accounts. Austin said it is doubtful the high volume of trading activity was the result of rebalancing in managed accounts, given participants' relatively low take up rates with them.

The question remains as to whether or not the participants who sought safety will migrate back to equities in the near term.

"We'll see, we're keeping our thumb on the pulse of that," said Austin.