U.S. stock index futures were set to open lower again on Tuesday, as investors fear more losses from major U.S. companies, and the slide in oil prices continue to weigh on energy companies. Futures for the S&P 500 were down 0.54 percent, Dow Jones Industrial Average futures were down 0.47 percent, and Nasdaq futures were down 0.48 percent. Citigroup fell about 17 percent on Monday, under pressure to sell its brokerage to Morgan Stanley. Aluminum giant Alcoa Inc., posted a wider-than-expected quarterly loss on Monday, but revenue was $700 million higher than expected, and the company's stock was little changed after-hours. Alcoa is expected to cut about 15,000 jobs.
