Stock index futures pointed to a lower open on Wall Street on Wednesday, as mounting fears over corporate results knocked down stock markets around the world.

* After the closing bell on Tuesday, aluminum firm Alcoa kicked off the eagerly awaited earnings season, reporting a second consecutive quarterly loss on shrinking demand and sharply lower prices, dampening investors' hopes to see positive surprises in corporate results.

* At 4:51 a.m. EDT futures for the S&P 500 were down 0.8 percent, Dow Jones futures were down 1.1 percent and Nasdaq 100 futures were down 0.8 percent.

* Alcoa shares traded in Frankfurt dropped 1.9 percent.

* Insurers will be in focus after The Wall Street Journal, citing people familiar with the matter, reported the U.S. Treasury Department plans to extend the Troubled Asset Relief Program to certain life insurers.

* The Treasury is expected to announce within the next several days the inclusion of life insurers that are bank holding companies or own a thrift, the Journal reported on its website. Several life insurers have applied, including Prudential Financial Inc
, Hartford Financial Services Group Inc and Lincoln National Corp , the Journal reported.

* European shares were down 1 percent on Wednesday morning, falling for a fourth consecutive session, with banks, insurers and mining shares such as HSBC , Swiss Life and BHP Billiton pacing the retreat, while Japan's Nikkei average dropped 2.7 percent.

* U.S. energy firms will feel the pinch of lower oil prices, down more than a dollar to below $48 a barrel, extending the previous day's sharp drop after U.S. inventory data fueled worries over demand.

* U.S. securities regulators meet on Wednesday to consider restrictions on short selling, a type of investing blamed by some lawmakers and executives for exacerbating the financial crisis and driving down share prices.

* On the macro front, the Federal Reserve is due to issue minutes from its meeting of March 17-18, while investors also awaited U.S. wholesale inventories data.

* U.S. stocks sank on Tuesday, with the Dow Jones industrial average <.DJI> fell 186.29 points, or 2.34 percent, to 7,789.56. The Standard & Poor's 500 Index <.SPX> lost 19.93 points, or 2.39 percent, to 815.55. The Nasdaq Composite Index <.IXIC> gave up 45.10 points, or 2.81 percent, at 1,561.61.

(Reporting by Blaise Robinson; editing by Mike Nesbit)