Stock index futures pointed to a lower open on Tuesday, with futures for the S&P 500, Dow Jones and Nasdaq down 0.4 to 0.6 percent at 0903 GMT.

* Investors are likely to be cautious after Japan raised the severity of the nuclear accident to the highest level, putting it on par with the Chernobyl 1986 disaster.

* Earnings news will be another focus, following Alcoa Inc reporting revenue that missed forecasts after the bell on Monday, sending its shares lower in post-market trade, despite reporting a first-quarter profit above expectations.

* Elsewhere, Chevron Corp , the second-largest U.S. oil company, said first-quarter exploration and production earnings would be higher than in the previous quarter.

* Brent crude extended overnight losses on concern high fuel prices will destroy demand and following Goldman Sachs recommendation on Monday to lock in trading profits.

* Looking at merger and acquisition news, two sources familiar with the matter told Reuters that Hewlett-Packard Co had considered buying business software company Tibco Software Inc until two weeks ago when talks fizzled.

* Staff at Taiwan unit Nan Shan Life Insurance Co Ltd have been urged by American International group Inc to voice their support for its planned $2.16 billion sale, saying their silence has allowed ill-intentioned groups to create negative impressions over the much-delayed deal.

* A former private equity executive was sentenced to 13 years and four months in prison for his role in a real estate investment fraud that federal authorities have called a $255 million Ponzi scheme targeting Orthodox Jews.

* The Wall Street Journal reported that the Bank of America Corp's internal auditors are reviewing why its chief financial officer and chief accounting officer were not consulted before the bank disclosed to investors that its dividend increase had been rejected by regulators.

* Inc said it is now offering a version of its Kindle device for $25 less, but that electronic book reader will include advertising.

* U.S. stocks mostly fell on Monday, with energy shares selling off on lower oil prices and concerns that company outlooks may fall short of expectations.

The Dow Jones industrial average <.DJI> rose 0.01 percent, the Standard & Poor's 500 Index <.SPX> fell 0.3 percent and the Nasdaq Composite Index <.IXIC> lost 0.3 percent.

* European shares fell on Tuesday after Japan raised the severity of its nuclear crisis to a level equal to that of Chernobyl, the world's worst nuclear disaster and on earnings concern after the revenue miss by Alcoa.

(Reporting by Joanne Frearson; Editing by Erica Billingham)