U.K. stocks dropped Monday, with the week starting off on risk-averse footing with energy shares under pressure as oil producers gather for industry talks. Oil shares were in the red Monday, as both members in and outside of the Organization of the Petroleum Exporting Countries were meeting this week in Algiers at the International Energy Forum. Investors will watch for any news that producers will agree to curb oil output at a time the market is grappling with an oil glut.

U.S. stocks extended losses Monday as worries about Germany's Deutsche Bank weighed on the financial sector while the upcoming U.S. presidential debate also contributed to jittery sentiment. Heavy losses for Deutsche Bank took a toll on European markets and pressured U.S. financial shares. U.S.-listed shares of Deutsche Bank DB, -7.06% DBK, -7.49% sank 7.1%, after Germany's Focus magazine reported over the weekend that Chancellor Angela Merkel wouldn't support state aid for the bank.

Declines in financial and commodities stocks sent Asian share markets broadly lower Tuesday, as markets eyed the first U.S. presidential debate for hints of future economic policy. Banks, insurers and other financial stocks in Japan opened lower, following a global fall in the sector overnight as concerns intensified over the health of Deutsche Bank AG DB1, -1.12% , after its shares slid 7.5% Monday to their lowest in decades.