U.S. stock index futures slipped on Tuesday as Kraft Foods Inc reached a deal to acquire Cadbury and earnings season picked up steam.

Kraft Foods lost 2.3 percent to $28.90 in premarket trade after the company agreed to a revised cash-and-stock deal to buy Cadbury for about $19.6 billion, creating the world's top confectioner.

The pace of corporate earnings builds this week, with Citigroup Inc and IBM Corp scheduled to report on Tuesday while Google Inc , Goldman Sachs Group Inc and American Express Co are due to post results later in the week.

The primary concern going into the day is Citigroup and the IBM earnings, said Andre Bakhos, president of Princeton Financial Group in North Brunswick, New Jersey.

That will give us a window into the heartbeat of the market.

Citigroup shares shed 0.6 percent to $3.40 ahead of its quarterly results.

S&P 500 futures fell 2.5 points and were below fair value, a formula that evaluates pricing by taking into account interest rates, dividends and time to expiration on the contract. Dow Jones industrial average futures fell 17 points, and Nasdaq 100 futures lost 0.75 point.

U.S. markets were closed on Monday for the Martin Luther King Jr Day holiday.

Industrial conglomerate Tyco International will acquire Broadview Security, which operates for Brink's Home Security Holdings Inc , for $1.9 billion in a deal that brings together two large providers of residential and commercial security in North America, the two companies said on Monday.

Brink's shares surged 33.7 percent to $42.00 in premarket.

Swiss Re agreed to transfer a U.S. life reinsurance contract to Warren Buffett's Berkshire Hathaway for $1.27 billion, enabling Berkshire to pocket premiums payable under the contract while taking responsibility for up to $1.5 billion in potential claims.

Apple Inc will host a special event on January 27 where it is widely expected to unveil its tablet computer, as the company looks to extend its hot hand into a brand new product category.

Goodyear Tire & Rubber Co shares fell 1.5 percent to $14.79 in light trade after the company said on Monday it expects to record a charge of about $150 million in the first quarter because of Venezuela's devaluation of its currency earlier this month.

On Friday, U.S. stocks slid after JPMorgan Chase & Co reported deep fourth-quarter loan losses and raised concerns about bank profits, while a weaker-than-expected Reuters/University of Michigan Surveys of Consumers for early January also hurt shares, as consumer worries about incomes and unemployment rose.

(Editing by Padraic Cassidy)