U.S. stock futures dropped sharply Monday, with financial turbulence back in the news as Citigroup Inc. said it would have to write down up to US$11 billion more of risky securities than it previously estimated.

In addition, Citigroup announced chairman and CEO Charles Prince would step down as chairman and chief executive officer. Robert Rubin, the former Treasury secretary, will be come chairman,

There are no major economic reports today from Statistics Canada.

The Canadian dollar opened at US106.95¢, off 0.09 cent, as the American dollar revived slightly from last week’s all-time lows.

South of the border, the U.S. Institute of Supply Management’s non-manufacturing index is due for release, and there are two speakers from the U.S. Federal Reserve due to deliver speeches.

In today’s M&A news, EnCana said it is paying US$2.55 billion buy out its partner’s half-interest in the Deep Bossier onshore natural gas field in Texas.

CIBC announced Sunday that it is its selling U.S. investment banking, equities, leveraged finance and debt markets businesses to Oppenheimer Holdings Inc. Those businesses employ about 700 people, but CIBC said it will maintain its corporate lending capability in the United States.

In earnings news, Ensign Energy Services reported a 52% slump in third-quarter profit to $49.7 million amid weaker demand and industry overcapacity in Western Canada.

Gold futures fell $4.40 to US$804.10 an ounce and crude slipped 78¢ to US$95.18 a barrel.

Overseas, the Hang Seng dropped 5% in Hong Kong. The FTSE 100 slipped 0.6% in London.

The Toronto Stock Exchange’s main index finished flat on Friday as a rally in commodity issues was offset by weaker financial stocks.

The S&P/TSX composite index finished down 8.66 points, or 0.06%, at 14,363.88.

The junior S&P/TSX Venture composite index gained 38.91 points, or 1.24%, to end at 3,170.59.

In New York, U.S. stocks posted modest gains after a roller coaster session.

The Dow Jones industrial average was up 27.23 points, or 0.20%, to end at 13,595.10. The S&P 500 was up 1.21 points, or 0.08%, at 1,509.65. The Nasdaq composite index was up 15.55 points, or 0.56%, at 2,810.38.

For the week, the Dow was down 1.53% and the S&P fell 1.67%, while the Nasdaq rose 0.22%.