NEW YORK (TheStreet) --The Dow Jones, NASDAQ, and S&P 500 all closed in the red on Friday. Additionally, the S&P 500 has now closed lower for nine consecutive trading sessions, its longest streak in nearly 36 years.

CNBC's Bob Pisani noted several problems U.S. markets are presently facing, causing them to go lower.

Crude Oil is down more than 10% this week, "that really is remarkable and one of the three problems," Pisani said.

Oil prices, uncertainties surrounding the U.S. Federal Reserve and a possible interest rate hike, and the upcoming U.S. presidential election results are those three problems.

Also, "you've got problems with drug stocks, oil stocks, and bond yields moving higher," Pisani added.

More from Markets

Video: Jim Cramer Reveals Why He's Cautious on Stocks

Video: Jim Cramer Reveals Why He's Cautious on Stocks

Stocks Slide Amid a Rise in Bond Yields, Strong Earnings

Stocks Slide Amid a Rise in Bond Yields, Strong Earnings

Jim Cramer on Earnings: All Stories Aren't Equal

Jim Cramer on Earnings: All Stories Aren't Equal

4 Stocks Making Important Moves Wednesday

4 Stocks Making Important Moves Wednesday

Dow Futures Turn Positive After Boeing Earnings Blowout; Twitter Boosts Nasdaq

Dow Futures Turn Positive After Boeing Earnings Blowout; Twitter Boosts Nasdaq