US STOCKS-Deal announcements lift stock index futures

* Abbot to buy Solvay's drugs unit for $6.6 billion

* Xerox will acquire ACS in a $6.4 billion deal

* For up-to-the-minute market news, click [STXNEWS/US] (Adds deal details, byline)

By Rodrigo Campos

NEW YORK, Sept 28 (Reuters) - U.S. stock index futures rose on Monday after three days of losses on Wall Street as more mergers and the last days of the third quarter encouraged investors.

Xerox Corp will buy Affiliated Computer Services Inc for $6.4 billion in a cash and stock deal that expands the copier company into technology outsourcing and data management. For details see [ID:nN2863430].

Xerox shares fell 8.8 percent to $8.23 in premarket trade while ACS shot up 27 percent to $60.

Abbott Laboratories said it would buy the drugs unit of Solvay in a $6.6 billion deal, giving Abbott full control of its Belgian development partner's cholesterol treatments and exposure to emerging markets. [ID:nLS426471].

Abbott stock edged up 1.5 percent.

"We're getting back into the routine of weekly (merger and acquisition) announcements, which is positive going forward," said Peter Cardillo, chief market economist at Avalon Partners in New York.

"Over the next couple of days we might see some window dressing. There's still a lot of money out there," Cardillo said, referring to the expected asset repositioning during the last days of the quarter.

S&P 500 futures rose 4.1 points and were above 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 gained 11 points and Nasdaq 100 futures added 6.5 points.

The Dutch biotechnology firm Crucell said Johnson & Johnson bought 14.6 million new Crucell shares for 302 million euros ($443.5 million) as part of a flu vaccine development deal [ID:nLS661406].

Data due Monday include the Federal Reserve Bank of Chicago releases its National Activity Index for August at 8:30 a.m. (1230 GMT). The index read -0.74 in July.

China Unicom <0762.HK>, that country's No. 2 mobile carrier, said Apple Inc's popular iPhone would be sold in China starting in October at a retail price of about $730 [ID:nHKG249644]. France Telecom's Orange also said it would sell iPhones later this year.

U.S. stocks fell for a third straight day on Friday on disappointing housing and durable goods data, while Research In Motion's Inc's lackluster results dented optimism about technology spending. (Editing by Padraic Cassidy) ((rodrigo.campos@thomsonreuters.com; + 1 646-223-6344; Reuters Messaging: rodrigo.campos.reuters.com@reuters.net))