Fear of military conflict helped to knock £40 billion off the value of London's stocks in three days, analysts said.
Investors' unease over escalating tensions between the USA and North Korea had weighed on stocks earlier in the day, pushing gold and bond prices slightly higher.
The negative headlines provided many investors with an opportunity to pocket some of their recent gains following a string of record highs fueled by strong corporate earnings.
"If the market truly believed the North Korea reaction was imminent, I think it would be down a lot more than it is", said Alan Skrainka, chief investment officer at Cornerstone Wealth Management.
The S&P had been down 0.52 percent at its session low. The index had its biggest drop since mid-May a day earlier. The Dow is up 48.61 points or 0.2% at 21,892.62, the Nasdaq is up 35.83 points or 0.6% at 6,252.71 and the S&P 500 is up 7.77 points or 0.3% at 2,445.98.
The Nasdaq Composite number was down 16.88 points, or 0.26 per cent, at 6,353.58.
The pan-European FTSEurofirst 300 index lost 1.01 percent and MSCI's gauge of stocks across the globe shed 0.26 percent for a weekly loss of 1.6 percent, the largest since the week to November 4. But some investors welcomed the dip in the sector, which has been S&P's leading gainer so far this year.
Many market participants have been calling for a significant decline on the S&P 500.
Mattis said North Korea must stop isolating itself and "stand down" in its pursuit of nuclear weapons, and Pyongyang "should cease any consideration of actions that would lead to the end of its regime and the destruction of its people".
The suspected range of North Korea's missiles based on their ICBM tests. Chris Jones IFLScience
In Asia, share markets remained pressured on Friday in morning session after US-North Korea geopolitical tensions came to the fore once again.
Demand for German government bonds - seen as one of the safest financial securities in the world - intensified on Friday as U.S. President Donald Trump issued a new round of fiery rhetoric against North Korea.
Trump delivered the fresh warning to reporters Thursday in Bedminster, New Jersey, after a lunch with Vice President Mike Pence, saying his comments Tuesday that the USA would bring down "fire and fury" on North Korea, maybe weren't tough enough.
There were fewer signs of anxiousness in the markets Friday.
The 30-year bond was last up 4/32 in price to yield 2.7871 percent, from 2.794 percent late on Thursday. It's still the highest it's been since May.
Nauert says the pressure by the US and others on Pyongyang "is working".
In the latest economic data, the consumer-price index (http://www.marketwatch.com/story/us-consumer-inflation-remains-soft-in-july-cpi-shows-2017-08-11) rose a seasonally adjusted 0.1% in July, its fifth straight month of softness, raising more questions about whether inflation will eventually rise to hit the Federal Reserve's 2% annual rate target. The figure reflected a 2.9 percent rise compared to one year ago.