* AstraZeneca rejects sweetened Pfizer offer
* AT&T to buy DirecTV for $48.5 billion
* Futures off: Dow 33 pts, S&P 4.5 pts, Nasdaq 7.75 pts
By Chuck Mikolajczak
NEW YORK, May 19 (Reuters) - U.S. stock index futures fell on Monday, on the heels of back-to-back weekly declines for the S&P 500 as investors grew cautious over stock valuations with indexes near record levels amid mixed economic data.
* U.S. listed shares of AstraZeneca slumped 11.6 percent to $71 in premarket trade after the British drugmaker rejected a sweetened and "final" merger offer from Pfizer which would have created the world's largest pharmaceuticals group. Pfizer shares advanced 2.2 percent to $29.77 before the opening bell.
* AT&T lost 2.1 percent to $35.95 in premarket trade after the telecom said it will acquire DirecTV for $48.5 billion, highlighting AT&T's pressing need for fresh avenues of growth beyond the maturing U.S. cellular business. DirecTV shares edged up 0.1 percent to $86.25 in premarket.
* Equities have come under pressure recently, with consecutive weekly declines for the first time since January as investors have become leery of growth prospects as a result of mixed economic data.
* Small-cap stocks, often seen as the first beneficiary of growth, have tumbled. The small-cap Russell 2000 index has approached correction territory, defined as a decline of 10 percent from a recent high, several times only to bounce back slightly.
* The defensive posture by investors has been reflected by a sector rotation into groups such as utilities, telecoms and energy, which have outperformed the broader S&P 500 over the past three months.
* S&P 500 e-mini futures lost 4.5 points and were roughly even with 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 e-mini futures declined 33 points and Nasdaq 100 e-mini futures lost 7.75 points.
* Earnings season will effectively draw to a close this week, with 23 companies scheduled to report, including retailers Home Depot and Lowe's Cos.
* Of 464 companies in the S&P 500 that have reported earnings so far, 69.2 percent beat expectations, above the long-term average of 63 percent and the 66 percent average over the past four quarters.
* European equities slid on Monday, pulled down by AstraZeneca after it rejected Pfizer's takeover bid, and by Deutsche Bank as a capital increase weighed on bank stocks.
* Asian share prices eased on Monday as investors waited to see if the world's major central banks will continue to keep monetary policy easy and in some cases loosen further. (Reporting by Chuck Mikolajczak; Editing by Bernadette Baum)