NEW YORK (TheStreet) -- Wall Street kicked off the week looking worse for wear on a myriad of concerns. 

First, there's the Federal Reserve which triggered fears and uncertainty after opting to leave rates unchanged at its September meeting. 

Next, China released fresh data that backed up worries that the world's second-largest economy is facing a slowdown. 

Then, the biotech sector saw even more losses as investors exited on fears of increased regulatory scrutiny in the industry.

It was a lot for investors to digest -- not to mention in a week already likely to see volatility ahead of the highly anticipated monthly release of jobs numbers on Friday. 

The S&P 500 closed 2.5% lower, the Dow Jones Industrial Average declined 1.9%, and the Nasdaq fell 3%. The Volatility Index, otherwise known as the "fear index,' spiked 15.4% to 27.25.

The number of jobs added to the U.S. economy during September will be released on Friday. Economists expect 200,000 jobs to have been added to nonfarm payrolls over the month, up from 173,000 in August. The unemployment rate is forecast to remain steady at 5.1%.

"The bias is going to be on the weak side until that [jobs] number comes out," Don Townswick, director of equities at asset management firm Conning, told TheStreet. "That's going to be the next thing that drives markets in one direction or another."

Benchmark indexes have been under pressure since the Fed opted to leave rates unchanged during its September meeting citing global market volatility as the main reason. The decision rattled investors who feared that the domestic and global economy was in worse shape than initially thought. 

The central bank will likely hike rates this year, New York Fed President William Dudley said at an event on Monday. However, he said that any decision would not be based on "calendar guidance."

"It depends on the data," he said. A year-end hike is "based on my view of how the economy is likely to evolve."

Meanwhile, Chicago Fed President Charles Evans made the case for a later rate hike in a speech at Marquette University on Monday afternoon. Evans said that normalizing monetary policy too soon would be risky for inflation and "subdued" wage growth. He also said inflation challenges presented by lower energy prices and a stronger U.S. dollar would likely not ease until the middle of 2016.

IMF Managing Director Christine Lagarde, in a newspaper interview, said that a forecast of 3.3% growth in the global economy this year wasn't likely and that next year's 3.8% GDP target was unrealistic. Lagarde noted that slowing growth in emerging economies and China was the culprit.

More weak data from China was also pressuring markets. Industrial profits in the world's second-largest economy fell 8.8% in August. The sharp decline followed on from a 2.9% drop in July. Since the beginning of the year, industrial profits have declined 1.9%.

The health care sector closed out its worst week in four years on Friday. The industry has been under pressure since Democratic presidential candidate Hillary Clinton vowed to address "price gouging" in the industry last Tuesday following the price increase of parasitic infection drug Daraprim from $13.50 to $750 a dose.

Gilead Sciences (GILD) - Get Report , Pfizer (PFE) - Get Report and Celgene (CELG) - Get Report were extending losses on Monday. The iShares Nasdaq Biotechnology ETF (IBB) - Get Report fell 6.3% and erased year-to-date gains.

Separately, five people have been charged with insider trading of Gilead, according to the Securities and Exchange Commission. Two advisers and one accountant, among others, allegedly traded on confidential information before news of Gilead's acquisition of Pharmasset became public.

Valeant Pharmaceuticals (VRX) plummeted more than 16% on reports U.S. House Democrats had asked to subpoena the company for documents related to drug price increases. This is the latest move in the government's attempts to regulate the industry. 

General Electric (GE) - Get Report was down 2.4% after it announced it will move production of gas-powered engines to Canada from Wisconsin after the company failed to access funds from the U.S. Export-Import Bank. Congress let government-run loan agency Ex-Im expire earlier this month.

Alcoa (AA) - Get Report will split into two businesses: an aluminium and mining company and a special metals group. The split is expected to be completed in the second half of 2016 and is part of a long-term strategy rather than activist investor pressure.