* Shire accepts Abbvie takeover offer
* Citigroup up in premarket after earnings, settlement
* Futures up: Dow 77 pts, S&P 8.25 pts, Nasdaq 18.75 pts (Adds Citigroup earnings, updates prices)
By Chuck Mikolajczak
NEW YORK, July 14 (Reuters) - U.S. stocks were poised for a higher open on Monday after the latest flurry of merger activity and earnings from Citigroup, putting the S&P 500 on track to rebound from its worst weekly decline since April.
* London-listed drugmaker Shire Plc succumbed to an increased 31 billion pounds ($53 billion) takeover offer from Abbvie Inc, ending a long-running courtship largely motivated by tax rates. U.S.-listed shares of Shire rose 1.6 percent to $253.08 while Abbvie shed 2.4 percent to $53.62 in premarket trade.
* Generic drugmaker Mylan Inc said it would buy Abbott Laboratories' specialty and branded generics business outside the United States in an all-stock transaction valued at about $5.3 billion. Mylan shares advanced 2.8 percent to $51.60 before the opening bell. Abbott shares rose 1.9 percent to $41.07 in premarket trade.
* Citigroup Inc shares rose 3.9 percent to $48.83 in premarket after it posted second-quarter earnings agreed to pay $7 billion to settle a U.S. government investigation into mortgage-backed securities.
* Earnings season will pick up speed this week, with 59 S&P 500 components scheduled to report. S&P 500 profits are seen growing 6.1 percent in the second quarter, according to Thomson Reuters data, down from the 8.4 percent growth forecast at the start of April. Revenue is seen up 3 percent.
* Analysts are looking to earnings for confirmation the economy recovered in the second quarter from the impact of a harsh winter in order to justify current stock prices.
* S&P 500 e-mini futures were up 8.25 points and fair value - a formula that evaluates pricing by taking into account interest rates, dividends and time to expiration on the contract - indicated a higher open. Dow Jones industrial average e-mini futures rose 77 points and Nasdaq 100 e-mini futures added 18.75 points.
* Engineering design firm AECOM Technology Corp on Sunday said it would pay about $4 billion to acquire engineering and construction services firm URS Corp. URS shares jumped 9.2 percent to $56.80 and AECOM gained 3.8 percent to $32.98 before the opening bell.
* Exelixis shares surged 12.2 percent to $3.73. The company's experimental skin cancer treatment being developed with Roche helped people with an advanced form of skin cancer live longer without their disease worsening when used in combination with another treatment, the companies said. (Reporting by Chuck Mikolajczak; Editing by Chizu Nomiyama and Nick Zieminski)