Thought it was over? Not even close. 

The extreme selloff that has characterized market activity so far this year kicked into high gear again on Friday as investors sold their positions heading into the three-day weekend. 

Stocks closed out at their lowest levels since August amid a renewed selloff in crude oil prices, fresh fears over China and a smattering of poor economic data out from the U.S. 

The S&P 500 closed 2.2% lower on Friday, the Dow Jones Industrial Average fell 2.4%, and the Nasdaq tumbled 2.7%. The Volatility Index, otherwise known as the "fear index," jumped 13.1% to 27.08.

If you thought this week was bad, it doesn't even compare with the week before. The S&P plunged nearly 6% the first week of the year. This week the decline was a relatively mild 2.2%

Since the beginning of the year, the S&P 500 has dropped 8% and the Dow has fallen 8.3%.

Both the S&P 500 and Dow are firmly in correction territory having fallen 12% and 13%, respectively, from their recent highs. A correction is marked by a drop of more than 10% from 52-week highs. 

A laundry list of weak economic data, including retail sales and industrial production, triggered fears the U.S. economy was following China in a slowdown, contributing to the selloff on Friday. A sustainable equity bounce will need an improvement in data following a disappointing end to the fourth quarter, according to one analyst. 

"Today's weak retail sales report almost ensures a sub-1% Q4 GDP print," Anthony Valeria, investment strategist for LPL Financial, told TheStreet. "Any meaningful bounce will likely require more signs of economic improvement."

Renewed fears over the Chinese economy triggered a selloff in crude oil prices on Friday. Concerns over Iranian oil flooding the market added to downward pressure after a Reuters report said the country is on track to ship 1.1 million barrels a day this month, up 20% from December.

West Texas Intermediate crude oil closed 5.7% lower at $29.42 a barrel, its worst settlement since November 2003. Commodities have been in selloff mode with little reprieve since the beginning of the year on oversupply concerns and demand worries.

The energy sector was the worst performer on markets Friday. Major oilers including Exxon Mobil (XOM - Get Report) , Royal Dutch Shell (RDS.A - Get Report) , BP (BP - Get Report) and Chevron (CVX - Get Report) were sharply lower, while the Energy Select Sector SPDR ETF (XLE - Get Report) fell 3.3%.

"As far as calling a bottom on oil, I haven't seen an analyst yet who has been successful in doing that," Mike Beale, managing director at the Private Client Reserve at U.S. Bank, told TheStreet. "We're likely going to see more volatility in oil and we'll see if we test these bottoms or not."

New York Federal Reserve President William Dudley contributed to uneasiness on Friday after talk of the Fed's rate hike plan surfaced. Dudley said while recent data has been "on the softer side" he expects economic growth at a pace above the long-term trend. His comments suggested the Fed could still be on track for four rate hikes this year after initiating its first in nearly a decade last month.

Wells Fargo (WFC - Get Report) slid 3.6% after disappointing quarterly revenue weighed on shares. The bank generated $21.6 billion in revenue, up 1% from a year earlier but below estimates of $21.84 billion. Quarterly profit of $1.03 a share came in a penny above expectations.

Jim Cramer owns Wells Fargo shares in his Action Alerts PLUS portfolio.

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Intel (INTC - Get Report) shares fell 9% despite a better-than-expected quarter. The tech company earned 74 cents a share, above forecasts of 63 cents, while revenue of $14.9 billion edged out expectations by $100 million.

Goldman Sachs (GS - Get Report) announced that it will take a $1.5 billion hit in its fourth quarter tied to the settlement of a mortgage-bond case. The investigation had been related to its "securitization, underwriting and sale of residential mortgage-backed securities" around a decade ago.

BHP Billiton (BHP) tumbled 6.9% after announcing it will take a $7.2 billion write-down on its U.S. shale oil and gas assets. The oil and mining company said the sharp fall in commodity prices had made the write-down necessary.