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.