On Monday, U.S. markets closed sharply lower and were headed for their worst quarter in 4 years as worried investors watched slumping Chinese economy and its potential effect on the timing of the Fed’s interest rate hike.

Among major benchmark indexes, the Nasdaq composite lost 3%, S&P 500 slumped more than 2% while Dow Jones Industrial Average suffered a loss of more than 300 points .

Most of the damage was caused by biotech and pharmaceutical stocks after some Democratic lawmakers criticized “massive” increase in prices of two heart drugs. The Democratic presidential candidate Hillary Clinton had already thrown the gauntlet in the ring against such “price gouging” by pharma companies.

The Nasdaq biotechnology index, NBI lost 6%, which was its worst single session drop since 2011. The index has lost heavily last week also when Hillary Clinton had criticized drug pricing.

On Monday, profits at Chinese industrial companies fell by 8.8%, thus increasing worries about the state of world’s second largest economy. This dismal report pushed down shares of energy and of raw material producing companies. Oil prices also dropped by more than 2%.

Although the U.S. economy delivered some healthy reports, as the U.S. consumer spending grew more than estimated in August. This helped boost talks of an interest hike by the Fed this year.

The Federal Reserve had left is interest rates unchanged in its September meeting, citing concerns about the global economy, especially China, among other economic factors.

Still, after that meeting many FOMC members publicly advocated a rate hike this year. Even the Fed Chair Janet Yellen personally supported a rate hike this year in one of her public speech.

On Monday, the New York Federal Reserve President William Dudley indicated that the central bank could start raising its rates as soon as October.

Many other Fed officials are scheduled to deliver public speeches during this week, including Chair Janet Yellen who will be speaking on Wednesday.

On Friday, investors will watch out for September non-farm payrolls data.