The sharp swings came one day after the steepest drop on Wall Street in 6 ½ years.
The Dow Jones industrial average traded 450 points lower after opening just above the flatline. The Federal Reserve may face a quandary: "they seem to want to raise interest rates (to fight feared inflation) but that may spook the stock market".
A 381-point surge on the Dow disappeared by Wednesday's closing bell as concerns about rising Treasury yields returned.
"History suggested the S&P 500 was overdue for a pullback: 404 trading days had elapsed since the market last experienced a 5 percent drawdown, the longest stretch of time in almost 90 years!"
The S&P 500, the benchmark for many index funds, rose 30 points, or 1.2 percent, to 2,611 as of 9:49 a.m.
The pan-European FTSEurofirst 300 index lost 1.74 percent and MSCI's gauge of stocks across the globe shed 0.02 percent.
On Wall Street, all but two S&P 500 sectors ended higher, led by gains in economically sensitive materials, technology and consumer discretionary indexes. Dow futures sank 0.5%.
Trading has been turbulent all day.
USA stocks climbed in early trading Wednesday as investors looked past concerns that a strong economy may accelerate the removal of monetary stimulus. It's switched between gains and losses several times since then.
Wall Street indexes repeatedly swung from positive to negative territory during the session.
Chris Hasenberg, owner of Hasenberg Financial Group in Eau Claire, pointed out that Monday's sell-off - the worst day for stocks in 6½ years based on percentage - combined with a 666-point drop on Friday only set the stock market back to about the point it was at on Christmas after an unusually strong 2017.
Corrections of up to 15 percent "are normal", said Oliver. If borrowing costs increase, bond investors will want more return - a higher yield. Higher Treasury yields make high-dividend stocks like utilities less appealing to investors seeking income. The last bear market was during the 2008 financial crisis.
PM Modi leaves on four-day visit to Palestine, UAE and Oman
He would also interact with leading businesspersons of Oman on developing stronger economic and business links with India. PM Modi's visit to Palestine has come after he hosted his friend Israeli Prime Minister Benjamin Netanyahu in India .
"People are dealing with the shock of seeing real inflation for the first time in a while", said Bruce McCain, chief investment strategist at Key Private Bank, as reported by CNN money.
"Based on where we stand relative to historic averages, there may be more pain ahead", David Lebovitz, global market strategist at JPM Asset Management, said in a message.
News agency Bloomberg reported that Thursday's sell-off wiped Dollars $120 billion of the collective wealth of the world's 500 richest people.
After Friday and Monday, traders and investors want to know if this is a short term correction, or something bigger. Experts do think the global economy will keep growing this year even though that is likely to bring more inflation.
Monday's move was a break from many months of relative calmness and left market participants grappling with an implosion of products that bet against volatility.
Advancing issues outnumbered declining ones on the NYSE by a 1.43-to-1 ratio; on Nasdaq, a 1.36-to-1 ratio favored advancers.
Wholesale gasoline lost 4 cents to $1.81 a gallon. Natural gas added 1 cent to $2.76 per 1,000 cubic feet.
The point is, volatility is unavoidable in investing. The Nasdaq composite rose 2.1 percent to 7,115.88. Hong Kong's Hang Seng skidded 5.1 percent and South Korea's Kospi declined 1.5 percent. The Cboe Volatility Index, a measure of market anxiety, dropped 27 percent.
In other commodities trading, copper fell 3 cents to $3.19 a pound.
CURRENCIES: The dollar edged up to 109.38 yen from 109.33 yen. The euro dipped to $1.2251 from $1.2263. But the Dow is up 24 percent in the past 12 months and the S&P 500 has gained 18 percent.
Volatility in equities, though, has also added to a bid to hold low-risk US government debt.